CN113287545B

CN113287545B - Method for relay culture of channel catfish

Info

Publication number: CN113287545B
Application number: CN202110635171.1A
Authority: CN
Inventors: 张朝晖; 刘肖汉; 郭闯; 陈静; 盖建军; 方苹
Original assignee: Jiangsu Fishery Technology Promotion Center
Current assignee: Jiangsu Fishery Technology Promotion Center
Priority date: 2021-06-08
Filing date: 2021-06-08
Publication date: 2024-02-09
Anticipated expiration: 2041-06-08
Also published as: CN113287545A

Abstract

The invention discloses a method for relay culture of channel catfish, wherein the pond area is 40-150 mu. The method mainly comprises the following steps: pond preparation, offspring seed stocking, water quality management, aquatic product variety capturing and other aspects. According to the invention, the pond ecological position is scientifically constructed by stocking large-specification longsnout catfish seeds, silver carp seeds and plagiognathops microlepis with proper density and specification, and environment-friendly water purifying agents such as polymeric ferric sulfate, 20% potassium hydrogen persulfate and EM bacteria are reasonably applied to adjust the pond water quality, so that the incidence rate of aquatic diseases is reduced, the use amount of fishing drugs is reduced, and the ecological environment of the pond and the quality safety of aquatic products are ensured; in the cultivation period of the near year, the commercial longsnout catfish with high peak-staggering sales uniformity and marketable specification and other matched cultivation fishes fully utilize the space and production efficiency of the pond, and the comprehensive economic benefit and ecological benefit of the pond are obviously improved.

Description

Method for relay culture of channel catfish

Technical Field

The invention belongs to the technical field of aquaculture, and particularly relates to a method for carrying out 2-batch channel catfish relay culture in a pond with an area of 40-150 mu in a culture period of nearly one year.

Background

In the existing cultivation mode of adult longsnout catfish, commercial longsnout catfish with standard goods specification (tail weight of 2.5 jin-3.2 jin) is cultivated from longsnout catfish fry ('metric separation fry'), the cultivation period is generally 2.5 years to 3 years, commercial longsnout catfish with standard goods specification is cultivated from large-specification longsnout catfish seeds (50 g/tail), the cultivation period is generally 1.5 years to 2 years, the cultivation period is long, the input cost is high, and the cultivation risk is high; the cultivation period is too long, so that the cultivation method is unfavorable for farmers to adapt to market consumption situation in time and quickly adjust cultivation modes, and the situation of high yield and low harvest frequently occurs.

In addition, in order to pursue unit yield and cultivation benefits, a part of farmers often increase the stocking amount of the longsnout catfish seeds to the greatest extent, and along with the increase of the growth specification of the longsnout catfish, the fishing load of the pond increases, and the pressure load of the water environment of the cultivation pond is obviously increased due to the accumulation effect of residual feed. Under the condition that the overwintering management of farmers is poor, the probability of occurrence of breeding diseases such as 'fulminant hemorrhage', 'intussusception' and the like of the longsnout catfish is increased. And then, the probability of preventing and treating fish diseases by abusing input products such as fishing drugs by farmers is increased, and great risks are brought to breeding production, product quality safety and environmental non-point source pollution.

In addition, in the common mode of adult fish culture of the longsnout catfish, the longsnout catfish is generally captured and sold before and after the spring festival, other aquaculture varieties bred in the time festival can be intensively marketed, and the market competition of aquatic products is large and the selling price is low; correspondingly, in 6 months-8 months each year, the commercial longsnout catfish with standard goods specification has small supply quantity, the marketing quantity of other competing products is not more, the selling price of the longsnout catfish with standard goods specification is always highest in the same cultivation period, and in general, the selling price of the longsnout catfish with standard goods specification can be higher than 1.5 yuan/jin-2.0 yuan/jin of the standard longsnout catfish sold before and after spring festival.

At present, domestic leiocassis longirostris consumer market terminals are mainly commercial catering, wherein the product form is mainly fresh leiocassis longirostris, and processed products such as leiocassis longirostris slices are used as auxiliary products; the market share of the household cooking consumer form is small.

The commercial specification of commercial longsnout catfish in domestic market is 4 kinds of specifications as follows: 1) Standard goods, also called Beijing goods, with tail weight of 2.5-3.2 jin, are mainly sold in Beijing and northwest areas; 2) The weight of the tail of the adult is 1.0 jin-1.5 jin, and the adult is mainly sold in southwest areas such as adult, chongqing, guiyang and the like; 3) The tail weight of the processed goods is about 2.0 jin, and the processed goods are mainly purchased by aquatic product processing enterprises; 4) The dead goods have a tail weight of more than 3.2 jin and are mainly purchased by aquatic product processing enterprises. In the same period, the standard goods of the longsnout catfish have the highest selling price which is generally higher than that of the commodity longsnout catfish with the specifications of ready-to-use goods, processed goods and dead goods by 1.0 yuan/jin-2.0 yuan/jin. The selling price of the processed goods and the dead goods is easily limited by processing enterprises, and the bargaining capability of farmers is at a disadvantage. Because the feeding habit of the longsnout catfish and the feed feeding management level of the farmers are limited, the longsnout catfish with the specifications exists in different proportions in the same adult fish culture pond, the farmers can only select and sell the longsnout catfish with the standard cargo specifications, and the rest of longsnout catfish with different specifications can only be sold at low price as the 'cargo-collecting' longsnout catfish, so that the comprehensive economic benefit of the culture pond is obviously reduced.

In view of the above limitation factors existing in the current adult fish culture of the longsnout catfish, a new mode and new technology for the adult fish culture of the longsnout catfish is created, so that the requirements of green development of modern fishery are met, the culture economic benefit of farmers can be improved, and the urgent requirements of continuous and healthy development of the adult fish culture industry of the longsnout catfish are met.

Disclosure of Invention

The invention aims to: aiming at the creation requirement of the new technical mode in the adult channel catfish culture, a new technical mode for relay culture of channel catfish is created, and the method has the characteristics that:

1) In the cultivation period of nearly one year, 2 large-size longsnout catfish seeds are cultivated, and the cultivation density of the longsnout catfish seeds is reasonably reduced, so that the amount of input products such as feed, fish drugs and the like is correspondingly reduced, and the pressure load on the water environment of the pond is reduced;

2) Matching the proper density and the specification of other aquatic products, making the joint of stocking stubbles, ecologically regulating the water quality of the pond, improving the water utilization rate of the pond, providing commercial longsnout catfish with the optimal market specification by staggering peaks, increasing the income of other aquatic products with a certain proportion, and obviously increasing the comprehensive economic benefit of the cultivation pond;

3) The water quality is reasonably regulated and controlled, and the culture tail water is recycled or discharged after reaching the standard.

The main technical key points of the cultivation method include:

1. the aquaculture objects are reasonably matched and put in culture. The stocking specifications and stocking densities of the various breeding objects are reasonably matched, and stocking stubbles are well joined;

2. and (5) preparing a pond. The area of the adult fish culture pond of the longsnout catfish is limited, and the facility conditions of the pond are optimized. The area of the pond is far larger than that of the existing adult catfish culture pond, and meanwhile, an air-assisted bait casting machine is selected to replace an existing single-body box-type bait casting machine; the feed feeding radiation range is enlarged, the feed utilization rate is improved, the probability of mutual scratch when the catfish robs the feed is reduced, and the occurrence rate of fish diseases is obviously reduced;

3. the fishing net is suitable for batch fishing. In the cultivation period (6-8 months), capturing commercial fish (standard goods) with the most suitable market specification in batches for sale, wherein the price and the selling price of the channel catfish with the most suitable specification are the highest, and the comprehensive economic benefit of the pond can be obviously increased when the channel catfish is sold in a peak-shifting manner; the method has the advantages that the culture density of the channel catfish can be obtained by batch capturing, a larger culture space can be made, each culture object in the channel catfish can be conveniently stored, the growth speed of the channel catfish can be improved, the time for the channel catfish to grow to the standard goods specification can be shortened, and the method has obvious advantages in the aspects of improving the specification uniformity, survival rate, yield and selling price of the commodity channel catfish, improving the utilization efficiency of the water body space in the channel catfish, and improving the ecological benefit.

4. And (3) applying the environment-friendly water purifying agent to adjust and improve the culture water quality for 6-9 months.

The technical scheme is as follows: the method for relay culture of channel catfish, disclosed by the invention, has the following main steps that the whole culture period is about one year (usually close to one year), and the method is divided into 4 main steps:

1. pond preparation period. Pond preparation in 1-2 middle ten days;

2. and (5) stocking fish seeds. 1) Breeding of channel catfish: 2, breeding plagiognathops microlepis fries and silver carp fries in the late 2 months, and breeding large-size Ictalurus punctatus fries in the early 3 months;

2) Breeding the channel catfish: in the late 8 months, the large-size longsnout catfish seeds of the 2 nd batch are bred, and the longsnout catfish seeds are supplemented until the mu breeding amount is 550-600 fish;

3. the breeding period of the channel catfish is 1. 3, 7-8 months, before 8 months, fishing and selling commercial products of marketable specifications, and performing water quality adjustment;

4. and (2) the breeding period of the channel catfish. And 9-11 months, carrying out, and capturing commodity longsnout catfish and other aquatic products in a dry pond.

The method specifically comprises the following main steps:

1. pond preparation

(1) Pond conditions

The area of the idle freshwater aquaculture pond after the completion of the previous batch of aquaculture is 40 mu-150 mu, the pond depth is 2.0m-2.6m, the water depth is 1.2m-2.4m, the water quality meets the secondary standard of the aquaculture tail water of the freshwater pond tail water discharge requirement, and the bottom silt is less than or equal to 15cm; is provided with equipment and facilities such as a bait casting machine, an aerator and the like which meet the requirements of conventional cultivation production.

1) Bait casting machine: preferably, a pond with the power of less than 60 mu is provided with 1 air-assisted bait casting machine with the power of 4kW and 1 single box-type bait casting machine with the power of 280W; the pond of 60 mu-150 mu is provided with 1 air-feeding bait casting machine with 4kW power and 2 single box bait casting machines with 280W power, and the 2 single box bait casting machines are arranged side by side with the interval of 40m-50m.

2) Oxygen-increasing machine: a pond with the area of 80 mu or less is provided with 1 impeller aerator with 3kW for every 10 mu; an 80-150 mu pond is provided with 8-10 impeller-type oxygen-increasing machines with 3 kW.

(2) Stocking fish seeds

1) Breeding of channel catfish:

300-400 plagiognathops microlepis with a stocking specification of 7-8 cm in the late 2 months;

in the next ten days of 2 months, stocking silver carp and bighead carp seeds with the specification of 1 jin/tail per mu, wherein the bighead carp seeds are 70 tails and 40 tails;

in the last ten days of 3 months, the large-size longsnout catfish seeds with the stocking specification of 1.5 jin/tail-1.7 jin/tail are 580-620 tail.

2) Breeding the channel catfish: and in the late 8 months, large-size longsnout catfish seeds with stocking specification of about 1.5 jin/tail are supplemented, and the stocking amount of the longsnout catfish seeds to mu is 550-600 tail.

2. Cultivation management

And when the high-quality commercial mixed feed for the longsnout catfish is reasonably fed, the quality of the cultured longsnout catfish is valued for optimizing. In the late 6 th ten days, the polymeric ferric sulfate is dissolved by pool water, the dosage is 30 g/mu.m, and the water is splashed in the whole pool, so that the transparency of the pool water is improved; on the following 3 rd day, the bottom is changed with a 20% potassium hydrogen persulfate tablet, and the sterilization is performed; and on the following 3 rd day, high-quality EM bacteria products are sprayed on the whole pool. And repeating the water quality regulation measures in the last ten days of each month in 7-9 months.

And (3) discharging the cultured tail water after the channel catfish is cultured to an ecological ditch or other idle ponds by using a 20% potassium hydrogen persulfate disinfection treatment.

3. Fishing and selling

And carrying out net fishing, namely only selecting the catfish with standard goods specification for sale, and then selecting the captured bighead carp and plagiognathops microlepis and stocking in a primordial pool.

The catfish is carried out in the middle ten days and the last month, the catfish is caught by a net, the catfish with standard goods specification is selected and sold on the market, the quantity of the catfish accounts for about 30 percent of the stocking quantity of the catfish, and the yield is about 480 jin/mu;

the catfish is carried out in the middle ten days and 7 months, the catfish is caught by a net, the catfish with standard goods specification is selected and sold on the market, the quantity of the catfish accounts for about 25% -30% of the stocking quantity of the catfish, and the yield is about 450 jin/mu;

the catfish is carried out in the middle ten days and 8 months, the catfish is caught by a net, the catfish with standard goods specification is selected and sold on the market, the quantity of the catfish is about 25% -30% of the quantity of the catfish seeds, and the yield is about 400 jin/mu; thus far, about 80% of the cultured longsnout catfish species are captured and sold, and about 10% of the non-captured longsnout catfish species are captured.

11, in the next ten days, lowering the water level, pulling a net and capturing in a dry pond, and selecting and selling commercial longsnout catfish bred by the 2 nd batch of bred longsnout catfish, wherein the yield per mu is about 1500 jin, the yield of the longsnout catfish in standard goods specification is about 70 percent, the yield of the longsnout catfish in standard goods specification is about 1000 jin/mu, the yield of the longsnout catfish in solid goods specification is about 30 percent, and the yield of the longsnout catfish in solid goods specification is about 500 jin/mu; the specification of the bighead carp is about 4 jin/tail, the yield is about 240 jin/mu, and the survival rate is about 85%; the specification of the silver carp is about 3.4 jin/tail, the yield is 112 jin/mu, and the survival rate is about 83%; the plagiognathops microlepis has the specification of about 270 g/tail, the yield of about 170 jin/mu and the survival rate of about 90 percent.

In order to better explain ideas in the aspects of seed stocking, technical scheme setting and the like, the biological habits of channel catfish, silver carp and bighead carp and plagiognathops microlepis and the angles of the biological habits on the utilization or repair of pond water bodies are briefly described as follows:

the channel catfish belongs to the bottom-layer warm water fish, is favored in a water quality fresh environment, has an optimal growth temperature of 26-30 ℃ and an optimal pH of 6.8-7.5, and has dissolved oxygen level which is preferably kept above 4mg/L in culture production, and the appetite, immunity and growth speed of the channel catfish are obviously influenced when the dissolved oxygen is lower than 3 mg/L; the channel catfish has the habit of feeding, snatching and eating more, and the phenomenon of satiety and distension caused by excessive feeding is easy; in addition, in case of an excessively high cultivation density, individuals struggle for feed, and their harder dorsal, pectoral and gluteal fins are liable to cause abrasion with each other and an infectious disease. The biological habit of the channel catfish is higher, and in the adult fish culture, if the culture specification is relatively uniform, the pond ecology is relatively good, the culture diseases are less generated, and the method has higher technical requirements on the aspects of stocking density, feeding mode, water quality regulation and the like.

The silver carp mainly absorbs floating algae in water, and proper amount of silver carp is bred to control excessive reproduction of blue algae and trichlorfon; bighead carp mainly filters zooplankton, and zooplankton feeds on zooplankton. In the freshwater aquaculture, plankton in the pond water is regulated and controlled by stocking silver carp seeds with certain density, so that the effect of regulating and improving water quality is achieved. However, in the actual high-density fish culture production, the eutrophication phenomenon of the culture water body is very common, that is, the water quality is regulated and optimized only by stocking silver carp seeds and even applying the technical measures of microbial preparations together, the regulating and optimizing effect is poor, and the comprehensive output is low.

The plagiognathops microlepis is middle-lower-layer small and medium-sized fishes, are omnivora, mainly ingest basal algae and putrescence which are rich in culture water and cannot be utilized by most economic fishes, also ingest feed residue in the water, have no food contradiction with other main culture fishes, and grow by fully utilizing the natural feed of the water, so that the plagiognathops microlepis has the advantages of less disease occurrence, high survival rate, fresh and delicious meat taste, high market acceptance and high economic value. The water quality of the pond can be regulated by culturing the plagiognathops microlepis with a certain density and a proper specification in the channel catfish culture pond, and the water quality of the pond can be regulated in cooperation with silver carp and bighead carp to obtain a certain yield so as to improve the comprehensive economic benefit of the pond.

The beneficial effects are that: according to the technical scheme, the stocking density of the 2-batch large-size longsnout catfish seeds and the effective engagement of the stocking stubbles of the longsnout catfish seeds are reduced, the feeding amount of the feed is reduced, and the negative effect that nutrients which are not fully utilized by the longsnout catfish seeds in the feed are dissipated to the pond water body to further deteriorate the water quality is weakened; by utilizing the air-assisted bait casting machine, the feeding range is enlarged, and the mutual scraping, damage and fish infection of the longsnout catfish when eating the feed are reduced; the water ecology of the pond is restored and regulated in situ by stocking silver carp seeds and plagiognathops microlepis with proper density and specification; the water quality is regulated by reasonably applying environment-friendly water purifying agents such as polymeric ferric sulfate, potassium hydrogen persulfate, EM bacteria and the like; by capturing commercial longsnout catfish with marketable specifications at proper time, the water-borne fishing load of the pond is reduced, a growing space is provided for the longsnout catfish which does not reach the marketable specifications, the survival rate, the specification uniformity and the feed utilization rate of the longsnout catfish are remarkably improved, and the comprehensive economic benefit of the pond is remarkably increased. In addition, after the breeding of the channel catfish 1 is finished and the pond is slightly subjected to bottom-changing disinfection measures, the channel catfish of the channel catfish 2 is bred, the water body has certain fertility and plankton, the water body of the pond is favorable for the growth of the channel catfish 2 and the survival rate of the channel catfish is obviously improved. By adopting the technical scheme, the ecological niche is scientifically constructed in the culture pond, the space and the production efficiency of the pond are fully utilized, and the comprehensive economic benefit and the ecological benefit of the pond are remarkably improved.

Detailed Description

The invention will be further elucidated with reference to specific examples.

Example 1 and example 2 were carried out on a south China water product Limited company base, and example 3 was carried out on a China water product farming plant base; comparative example 1 was conducted at the south China aquatic products limited company base, and comparative example 2 was conducted at the Litsea county, which is a China aquatic products farming plant base.

The aquatic offspring seed used in the above examples and comparative examples are commercially available as inputs of polymeric ferric sulfate, potassium hydrogen persulfate, feed for longsnout catfish, and the like.

Example 1

The implementation site is at a south China aquatic product limited company base, the implementation time is 1 month in 2020-12 months in 2020, the pond is numbered 1# in North China, the area is 59 mu, the pond depth is 2.5m, the water depth is 1.2m-2.4m, the bottom sludge is less than or equal to 15cm, the water inlet and the water outlet are convenient, and the water quality of the source water meets the water quality requirement of freshwater aquaculture; the pond is provided with 1 air-assisted bait casting machine with 4kW power and 1 single box-type bait casting machine with 280W power, and 5 impeller-type oxygen-increasing machines with 3kW power are provided; pool water disinfection and other preparation works are carried out before the seedlings are put in culture.

1. Stocking fish seeds

1) Breeding of channel catfish:

for 2 months and 22 days, 312 plagiognathops microlepis with a mu stocking specification of 7cm-8cm (13 plains/jin) and a total stocking of 1416 jin (6 yuan/jin);

for 2 months and 23 days, 40 tail silver carp seeds with 1 jin/tail per mu are bred, and 2360 jin (3 yuan/jin) of silver carp seeds are bred in total; 1 jin of bighead carp seeds per mu are bred with 70 tails, and 4130 jin (5 yuan per jin) of bighead carp seeds are bred in total;

600 catfish tails with a specification of 1.62 jin/tail are bred for 3 months and 2 days, and 57348 jin (6.5 yuan/jin) are bred in total.

2) Breeding the channel catfish: for 8 months and 21 days, 550 catfish with a mu stocking specification of 1.54 jin/mu are bred, 49973 jin (7 yuan/jin) are bred in total, and estimated, the catfish seeds stored in the pond are about 600 catfish seeds/mu.

2. Cultivation management

1) And (5) feeding feed. During the breeding period, the special high-quality compound feed with the grain diameter of 5.0mm and the crude protein content of 32% for the longsnout catfish is bred and fed, and the sinking feed and the floating feed are selected and fed according to the water temperature;

2) Water quality regulation

For 6 months and 19 days, the polymeric ferric sulfate is dissolved by using pond water, the mu consumption is 50 g, and the water is splashed in the whole pond, so that the transparency of the pond water is improved; for 24 days in 6 months, the bottom of the container is changed to be sterilized by a 20% potassium hydrogen persulfate tablet, and the dosage per mu is 200 g; and (5) splashing high-quality EM bacteria products into the whole pool after 26 days of 6 months, and using according to the product specifications.

7 months, 8 months and 9 months, and repeating the water quality regulation measures according to weather conditions in the middle and the last ten days of each month.

3. Fishing and selling

1) Breeding of channel catfish:

For 6 months and 3 days, the catfish capturing amount in standard goods is 27424 jin (465 jin/mu) and the standard is about 2.54 jin/tail; for 7 months and 8 days, the catfish capturing amount in standard goods is 27293 jin (463 jin/mu) and the standard is about 2.57 jin/tail; the catching amount of the standard catfish is 20482 jin (347 jin/mu) and the standard catfish is about 2.63 jin/tail after 8 months and 11 days.

2) Breeding the channel catfish:

the water level is reduced for 28 days in 11 months, the net pulling and the dry pond are used for capturing, the total capturing amount of the catfish is 87438 jin, the mu yield is 1482 jin, and the survival rate is 88%, wherein the standard specification of the catfish is 57065 jin (mu yield is 967.2 jin), the dead specification of the catfish is 30373 jin (mu yield is 514.8 jin), and the ratio is 70% and 30% respectively;

the total captured silver carp is 6620 jin (the per mu yield is 112.2 jin), the specification is 3.4 jin/tail, and the survival rate is 82%;

the total of 13402 jin of bighead carp is captured (227 jin of mu yield), the specification is 3.85 jin/tail, and the survival rate is 84%;

10319 jin (175 jin per mu yield) of plagiognathops microlepis are captured in total, the specification is 0.66 jin/tail, and the survival rate is about 85%;

4. yield, value, cost, benefit

1) Yield:

longsnout catfish: the total yield is 162638 jin, the catfish seeds are 107321 jin, and the weight of the catfish is increased by 55317 jin;

silver carp: the total yield is 6620 jin, the per mu yield is 112.2 jin, the specification is 3.4 jin/tail, and the survival rate is 82%;

bighead carp: total yield 13402 jin, mu yield 227 jin, specification 3.85 jin/tail, survival rate 84%;

plagiognathops microlepis). The total yield is 10319 jin, the per mu yield is 175 jin, the specification is 0.66 jin/tail, and the survival rate is about 85%.

2) Yield value:

total yield value 1508849 yuan, mu average yield value 25574 yuan.

3) Cost:

the total cost of investment is 1171205 yuan. Comprising the following steps:

a. aquatic offspring seed:

aquatic fingerling 758799 yuan, ictalurus longus fingerling 372762 yuan, ictalurus longus fingerling 2 nd 349811 yuan, silver carp 7080 yuan, bighead carp 20650 yuan, plagiognathops microlepis 8496 yuan;

b. feed: the feed cost is 281426 yuan, the feed consumption is 102337 jin, and the feed unit price is 2.75 yuan/jin;

c. fish drug input:

the cost is 306880 yuan when the environment-friendly water purifying agents such as disinfection, disinsection, polymeric ferric sulfate, potassium hydrogen persulfate, EM bacteria and the like are purchased;

d. pond renting and manual work: 70800 yuan for pond renting, 16520 yuan for manpower, and 87320 yuan for total;

e. electric charge: 6490 yuan;

f. small tools and machinery maintenance, depreciation: 6490 yuan.

4) Benefits are:

a. economic benefit: the total economic benefit is 337644 yuan, and the per mu economic benefit is 5723 yuan.

b. Ecological benefit:

respectively at the bottom of 6 months, the bottom of 7 months, the bottom of 8 months, the bottom of 9 months and the bottom of 11 months, namely after water quality regulation measures such as EM bacteria are applied to each month, collecting a water sample according to a national standard detection method, and carrying out total nitrogen, total phosphorus, suspended matters, pH and COD on the water quality of the pond _Mn And measuring the physicochemical indexes. The measurement results were as follows:

measuring time	Total nitrogen mg/L	Total phosphorus mg/L	Suspended matter mg/L	pH	COD _Mn mg/L
						6 months 30 days	1.89	0.29	14.00	8.50	8.38
7 months 30 days	3.33	0.79	14.00	8.32	11.28
						8 months and 30 days	4.31	0.96	22.10	8.32	10.90
9 months and 30 days	3.87	0.94	16.60	8.48	12.06
						11 months and 30 days	3.42	0.82	15.30	8.27	11.38

In summary, the technical scheme adopted by the invention not only obviously increases the comprehensive economic benefit of the culture pond, but also has excellent water quality physicochemical indexes in the whole culture period; the economic benefit and the ecological benefit are very obvious.

Example 2

The implementation site is in a north 2# pond of a south China aquatic product limited company, the implementation time is 1 month in 2020 to 12 months in 2020, the pond area is 48 mu, the pond depth is 2.5m, the water depth is 1.2m to 2.4m, the bottom sludge is less than or equal to 15cm, the water inlet and the water outlet are convenient, and the water quality of the source water meets the water quality requirement of freshwater aquaculture; the pond is provided with 1 air-assisted bait casting machine with 4kW power and 1 single box-type bait casting machine with 280W power, and 5 impeller-type oxygen-increasing machines with 3kW power are provided; the preparation before the stocking of the offspring was the same as in example 1.

The fish fry stocking variety, specification and time are the same as in example 1, and the stocking density of each aquatic fry per mu is: 400 plagiognathops microlepis, 40 silver carp seeds, 70 bighead carp seeds, 500 channel catfish seeds, and 620 channel catfish seeds. Cultivation management measures such as feed feeding and water quality regulation are as same as in the embodiment 1; the fishing marketing strategy is described in example 1.

Yield, yield value, cost and benefit comprehensive evaluation:

1) Yield:

the total yield of the catfish is 125316 jin, wherein the catfish of the 1 st catfish is 56654 jin and the catfish of the 2 nd catfish is 68662 jin; 5386 jin of silver carp yield; the bighead carp yield is 11011 jin; 7670 jin of plagiognathops microlepis.

2) Yield value:

the comprehensive yield of the pond is 1138698 yuan, wherein the yield of the longsnout catfish is 990133 yuan, the yield of the silver carp is 13464 yuan, the yield of the bighead carp is 66067 yuan, and the yield of the plagiognathops microlepis is 69034 yuan.

3) Cost:

the total cost of investment is 971292 yuan, wherein, the cost of seedlings is 599776 yuan, the cost of feed 265035 yuan, the cost of fish drug investment is 24943 yuan, the cost of pond renting and manual operation is 70992 yuan, the cost of electricity is 5276 yuan, the cost of small tools and mechanical maintenance are reduced by 5276 yuan.

4) Benefits are:

a. the economic benefit is 167400 yuan, and the per mu average benefit is 3488 yuan.

b. Ecological benefit:

according to the set scheme, water samples are collected in each month as in the example 1, and the physicochemical indexes below the pond water quality are monitored. The measurement results were as follows:

measuring time	Total nitrogen mg/L	Total phosphorus mg/L	Suspended matter mg/L	pH	COD _Mn mg/L
						6 months 30 days	1.84	0.34	14.00	8.50	8.22
7 months 30 days	3.16	0.66	15.00	8.37	10.41
						8 months and 30 days	4.31	0.85	19.52	8.42	10.56
9 months and 30 days	3.47	0.91	15.80	8.57	11.76
						11 months and 30 days	3.26	0.77	14.92	8.19	11.13

In examples 1 and 2 above, the EM bacteria product was Jiangsu Runfu Biotechnology Co., ltd, vitality source "Jingba".

The breeding of the longsnout catfish has been developed in China for more than 30 years, and the feed development and feed feeding method are very mature. The design of the cultivation method ensures that the cultivation requirement of the method can be met by adopting mature feed and a feeding method without specially developing a new feeding method and feed.

In the cultivation process, the sinking pellet compound feed is fed when the water temperature is 10-15 ℃ or the water temperature is higher than 30 ℃ in general; the water temperature is higher than 15 ℃ and lower than 30 ℃ for feeding floating granular compound feed.

The area of the traditional catfish culture pond is generally 10-30 mu, a box-type bait casting machine is arranged in many cases, if the area of the pond is too large, the radiation range of the box-type bait casting machine is insufficient, and the catfish is easy to scratch each other when robbing, so that culture diseases occur.

The method is designed for ponds of 40-150 mu, and is particularly suitable for the existing air-assisted bait casting machine. Generally, a pond of 50-60 mu is suitably equipped with 1 wind-driven bait feeder, and a pond of 100-150 mu is suitably equipped with 2 wind-driven bait feeders.

Example 3

The implementation site is a Hua aquatic product culture factory base in the county of producing water, the implementation time is 1 month in 2020 to 12 months in 2020, the pond number is A1, and the area is 150 mu; the pond depth is 2.8m, the water depth is 1.2m-2.4m, the bottom sludge is less than or equal to 12cm, the water inlet and the water discharge are convenient, and the water quality of the source water meets the water quality requirement of freshwater aquaculture; 1 single box type bait casting machine with 4kW power and 2 single box type bait casting machines with 280W power are equipped, and the 2 single box type bait casting machines are arranged side by side, and the interval is 50m; 10 waterwheel type oxygen-increasing machines with the size of 3kW are arranged.

1. Stocking fish seeds

1) Breeding of channel catfish:

plagiognathops microlepis). 2 months and 8 days, the total stocking is 3500 jin (7 yuan/jin) of plagiognathops microlepis with 15 tail/jin;

silver carp: for 2 months and 17 days, 40 tail/mu of silver carp seeds with the stocking specification of 1 jin/tail are stocked with 6000 jin (2.8 yuan/jin) in total;

bighead carp: for 2 months and 17 days, raising the bighead carp seeds with the specification of 1 jin/tail and 70 tails/mu, and adding up to 10500 jin (5 yuan/jin);

longsnout catfish: for 2 months and 28 days, the catfish with the stocking specification of 1.53 jin/tail is bred with 650 tails/mu, and the total stocking is 149175 jin (6.5 yuan/jin).

2) Breeding the channel catfish:

longsnout catfish: for 8 months and 20 days, the total stocking of the 590-tail longsnout catfish with the specification of 1.58 jin/tail is 139830 jin (7 yuan/jin), and the estimated catfish seeds in the pond are about 650-tail/mu.

2. Cultivation management

The cultivation management measures such as feed feeding and water quality control are as described in example 1.

3. Fishing and selling

1) Breeding of channel catfish:

For 6 months and 4 days, selecting standard specification longsnout catfish, 2.55 jin/tail, and counting 68085 jin;

7 months and 8 days, selecting standard specification longsnout catfish, 2.62 jin/tail, and counting 71919 jin;

for 8 months and 3 days, selecting standard specification longsnout catfish, 2.34 jin/tail, and counting 66690 jin; the total weight of 3 batches is 206694 jin.

2) Breeding the channel catfish:

for 11 months and 20 days, the water level is reduced, the catfish is carried and captured in a dry pond, 219090 jin of the catfish is totally captured, the mu yield is 1460.6 jin, the survival rate is 86.4 percent, wherein the standard specification catfish is 135930 jin (mu yield 906.2 jin), the dead cargo specification catfish is 83160 jin (mu yield 554.4 jin), and the ratio is 62 percent and 38 percent respectively;

16320 jin of silver carp is captured (the yield per mu is 108.8 jin), the specification is 3.2 jin/tail, and the survival rate is 85%;

34200 jin of bighead carp is captured (the per mu yield is 228 jin), the specification is 3.8 jin/tail, and the survival rate is 85.7%;

20328 jin (mu yield 135.5 jin) of plagiognathops microlepis is captured in total, the specification is 0.44 jin/tail, and the survival rate is about 88%.

4. Comprehensive evaluation of yield, yield value, cost and benefit

1) Yield: the total yield of the longsnout catfish is 425784 jin, and the weight is increased by 136779 jin; 16320 jin of silver carp, 34200 jin of bighead carp and 20328 jin of plagiognathops microlepis.

2) Yield value: total yield 3723029 yuan.

3) Cost: the total cost is 3064611 yuan; wherein, the cost of the offspring seeds is 2042248 yuan, the cost of the feedstuff is 695863 yuan, the cost of the fish drug is 75000 yuan, the cost of the pond renting and manual operation is 220000 yuan, the cost of electricity is 16500 yuan, the small tool and the mechanical maintenance are reduced by 15000 yuan.

4) Benefits are:

a. economic benefit, total economic benefit 658418 yuan, per mu average benefit 4389 yuan.

b. Ecological benefit:

measuring time	Total nitrogen mg/L	Total phosphorus mg/L	Suspended matter mg/L	pH	COD _Mn mg/L
						6 months 30 days	1.77	0.41	14.00	8.43	8.15
7 months 30 days	3.34	0.59	15.00	8.51	9.61
						8 months and 30 days	3.93	0.76	18.40	8.38	9.74
9 months and 30 days	4.24	0.88	16.10	8.66	10.83
						11 months and 30 days	3.53	0.61	14.52	8.27	10.67

Comparative example 1

Comparative example 1 is developed on a south China aquatic product limited company base, the implementation time is 2020 month 1 to 2020 month 12 months, pond numbers are south # 1, the area is 46 mu, the pond depth is 2.5m, the water depth is 1.2m to 2.4m, the bottom sludge is less than or equal to 15cm, water inlet and drainage are convenient, and the water quality of source water meets the water quality requirement of freshwater aquaculture; the pond is provided with 1 air-assisted bait casting machine with 4kW power and 1 single box-type bait casting machine with 280W power, and 5 impeller-type oxygen-increasing machines with 3kW power are provided; the preparation before the stocking of the offspring was the same as in example 1.

1. Seedling stocking

For 2 months and 23 days, 60 chubs with the specification of 1 jin/tail are bred per mu, and 2760 jin (3 yuan/jin) are bred in total; 1 jin of bighead carp seeds per mu are bred with 140 tails, and 6440 jin (5 yuan per jin) of bighead carp seeds are bred in total;

for 3 months and 2 days, 900 catfish with the specification of 1 jin/tail per mu are bred, and 41400 jin (6.8 yuan/jin) of catfish are bred in total.

2. Cultivation management

2) Water quality regulation

The biological preparation of quicklime and EM bacteria is used for regulating the water quality.

3. Fishing and selling

And (3) carrying out fishing net capturing for 8 months and 12 days, only selecting the leiocassis longirostris with standard specification for sale, and stocking the captured bighead carps in a stock pool after selecting.

And (3) reducing the water level after 28 days of 11 months, pulling a net and capturing in a dry pond, and capturing the longsnout catfish, the silver carp and the bighead carp.

4. Yield, yield value, cost and benefit comprehensive evaluation:

1) Yield: the total yield of the longsnout catfish is 124660 jin, and the weight is increased by 83260 jin; silver carp 7741.8 jin and bighead carp 19872 jin.

2) Yield value: total yield value 926997 yuan, mu average yield value 20152 yuan.

3) Cost: the total cost is 826597 yuan; wherein, the cost of the offspring seeds is 322000 yuan, the cost of the feedstuff is 412137 yuan, the cost of the fish drug input is 18400 yuan, the cost of the pond renting and manual 64400 yuan, the cost of electricity is 5060 yuan, the small tool and the mechanical maintenance are reduced by 4600 yuan.

4) Benefits are:

a. the economic benefit is 100400 yuan, and the per mu average benefit is 2182.6 yuan.

b. Ecological benefit:

according to the set scheme, water samples are collected in each month as in the example 1, and the physicochemical indexes below the pond water quality are monitored.

The measurement results were as follows:

measuring time	Total nitrogen mg/L	Total phosphorus mg/L	Suspended matter mg/L	pH	COD _Mn mg/L
						6 months 30 days	1.89	0.29	14.00	8.50	8.38
7 months 30 days	3.33	0.79	14.00	8.32	11.28
						8 months and 30 days	4.31	1.44	15.80	8.32	10.90
9 months and 30 days	5.11	1.41	16.60	8.08	12.06
						11 months and 30 days	4.43	1.22	22.00	8.27	12.38

Compared with the existing technical scheme for culturing adult longsnout catfish, the technical scheme provided by the invention can provide commercial longsnout catfish with the most accepted standard goods specification in the consumer market in a plurality of batches by peak shifting, reduces the influence of market risks, and has obvious economic benefit due to the synergistic effect of 1300 yuan to 3500 yuan per mu.

The embodiment 1, the embodiment 2 and the embodiment 3 show that the main physical and chemical index monitoring value of the pond water quality in the whole culture period is better than the secondary standard value required by the tail water discharge of the freshwater aquaculture by applying the technical scheme of the invention; the monitoring value of the water quality index of partial total nitrogen and total phosphorus in the comparative example 1 is higher than the secondary standard value required by the tail water discharge of the freshwater aquaculture, which shows that the technical scheme of the invention has very obvious ecological benefit.

Claims

1. A method for relay culture of channel catfish is characterized in that the whole culture period is less than one year and is divided into four aspects:

1) Pond preparation: pond preparation is carried out in the middle of 1 month-2 months;

2) Breeding fish seeds:

2.1 Breeding the Ictalurus longus 1: 2, breeding plagiognathops microlepis fries and silver carp fries in the late 2 months, and breeding large-size Ictalurus punctatus fries in the early 3 months;

2.2 Breeding the channel catfish of step 2): in the late 8 months, the large-size longsnout catfish seeds of the 2 nd batch are bred, and the longsnout catfish seeds are supplemented until the mu breeding amount is 550-600 fish;

3) And (3) cultivation management:

reasonably feeding the special high-quality compound feed for the longsnout catfish; timely optimizing the culture water quality;

4) Fishing;

4.1 Catfish of channel 1) fishing:

3, during the middle ten days of 3 months to 7 months to 8 months, carrying the catfish to catch and sell commodity longsnout catfish with proper specification, and performing water quality adjustment;

4.2 Catfish 2 nd:

9 months to 11 months, carrying out lift and capturing commodity longsnout catfish in a dry pond;

in the step 2):

2.1 Breeding the Ictalurus longus 1:

silver carp and bighead carp seeds with 1 jin/tail stocking specification are bred in the late 2 months, wherein the bighead carp seeds are 70 tails and 40 tails;

in the last ten days of 3 months, the large-size longsnout catfish seeds with the per mu stocking specification of 1.5 jin/tail-1.7 jin/tail are 580-620 tail;

2.2 Breeding the channel catfish of step 2):

in the late 8 months, large-size longsnout catfish seeds with stocking specification of about 1.5 jin/tail are supplemented, and the stocking amount of the longsnout catfish seeds is 550-600 tail per mu;

in the step 3):

3.1 Water quality adjustment:

and (3) adjusting the quality of the culture water in the last ten days of each month for 6-9 months, wherein the method comprises the following steps: dissolving polymeric ferric sulfate with pond water, wherein the dosage is 50+/-2 g/mu, and sprinkling the polymeric ferric sulfate in the whole pond to improve the transparency of the pond water; on the following 3 rd day, the bottom is changed with a 20% potassium hydrogen persulfate tablet, and the sterilization is performed; on the following 3 rd day, high-quality EM bacteria products are sprayed on the whole pool;

the method comprises the steps of (1) pumping the culture tail water after the catfish is caught, and sterilizing the tail water by using 20% potassium hydrogen persulfate;

3.2 Feeding:

1) Feeding feed:

feeding a special high-quality compound feed for the longsnout catfish with the grain diameter of 5.0mm and the crude protein content of 32 percent; feeding the sinking feed and the floating feed according to the water temperature, and feeding the sinking pellet compound feed when the water temperature is 10-15 ℃ or the water temperature is higher than 30 ℃; the water temperature is more than 15 ℃ and less than 30 ℃ for feeding floating particle compound feed;

in the step 4):

4.1 Fishing net, namely, only selecting the catfish with standard goods specification for sale, and stocking the captured bighead carp and plagiognathops microlepis in a primordial pool after selecting:

the fish is carried out for net catching in the middle ten days and the standard specification longsnout catfish is selected for marketing and sales, wherein the quantity of the standard specification longsnout catfish accounts for 30+/-1.5% of the breeding quantity of the longsnout catfish seeds, and the yield is 480+/-24 jin/mu;

the fish is carried out for net catching in the middle ten days and 7 months, the standard specification longsnout catfish is selected for marketing and sales, the quantity of the standard specification longsnout catfish accounts for 25% -30% of the breeding quantity of the longsnout catfish seeds in the 1 st step, and the yield is 450+/-22 jin/mu;

the catfish is carried out in the middle ten days and 8 months, the catfish is caught by a net, the catfish with standard goods specification is selected and sold on the market, the quantity of the catfish seeds is 25% -30%, and the yield is 400 jin/mu;

to this end, 80±2% of the longsnout catfish seeds bred in the 1 st batch are captured and sold, and the uncaptured longsnout catfish seeds account for 10±1%;

4.2 11 months, the water level is reduced, the net is pulled and the dry pond is used for capturing, the commercial longsnout catfish bred by the 2 nd batch of bred longsnout catfish is selected and sold, and the mu yield is 1500+/-30 jin; wherein:

the standard specification of the longsnout catfish accounts for 70+/-3 percent, and the yield is 1000+/-20 jin/mu;

the catfish with the specification of the dead cargo accounts for 30+/-1 percent, and the yield is 500+/-10 jin/mu;

the specification of the bighead carp is 4+/-0.2 jin/tail, the yield is 240+/-5 jin/mu, and the survival rate is 85+/-4%;

the specification of the silver carp is 3.4+/-0.1 jin/tail, the yield is 112+/-2 jin/mu, and the survival rate is 83+/-3%;

the plagiognathops microlepis has the specification of 270+/-0.50 g/tail, the yield of 170+/-3 jin/mu and the survival rate of 90+/-4%;

step 1) pond preparation:

the area of the idle freshwater aquaculture pond after the completion of the previous batch of aquaculture is 40 mu-150 mu, the pond depth is 2.0m-2.6m, the water depth is 1.2m-2.4m, and the bottom sludge is less than or equal to 15cm;

is provided with a bait casting machine and an aerator which meet the requirements of conventional cultivation production:

1) Bait casting machine:

a pond with the power of less than 60 mu is provided with 1 air-assisted bait casting machine with the power of 4kW and 1 single box-type bait casting machine with the power of 280W;

a pond of 60 mu-150 mu is provided with 1 air-feeding bait casting machine with 4kW power and 2 single box-type bait casting machines with 280W power, and the 2 single box-type bait casting machines are arranged side by side with a spacing of 40m-50m;

2) Oxygen-increasing machine:

a pond with the area of 80 mu or less is provided with 1 impeller aerator with 3kW for every 10 mu;

an 80-150 mu pond is provided with 8-10 impeller-type oxygen-increasing machines with 3 kW.