WO2020190151A1

WO2020190151A1 - Treatment composition for a marine ectoparasite and a method for preparing the treatment composition

Info

Publication number: WO2020190151A1
Application number: PCT/NO2020/050079
Authority: WO
Inventors: Joseph Gibbons; Gordon Ritchie
Original assignee: Mowi ASA
Priority date: 2019-03-21
Filing date: 2020-03-20
Publication date: 2020-09-24
Also published as: NO20190379A1; NO20200335A1

Abstract

Hypersaline composition for use in a therapeutic, topical treatment of a fish infected with an ectoparasite and said treatment is safe to fish welfare, where the hypersaline composition comprises one of: - sea water salts and freshwater; - sea water salts and sea water; and - a NaCl solution and sea water, and the total salinity of the hypersaline composition is in the range from and including 50 ppt and up to and including 58 ppt, and where the fish is treated for a duration in the time interval from and including 30 minutes up to and including 60 minutes.

Description

TREATMENT COMPOSITION FOR A MARINE ECTOPARASITE AND A METHOD FOR PREPA

RING THE TREATMENT COMPOSITION

This invention concerns a hypersaline composition for use in a therapeutic, topical treat ment of a fish infected with an ectoparasite. The topical treatment is a bath treatment of the fish infected with the ectoparasite. In particular, the invention concerns treatment of farmed fish. Said farmed fish may be a marine fish or a salmonoid fish. The ectoparasite may be a crustacean ectoparasite such as a sea louse or an amoeba. The amoeba may cause Amoebic Gill Disease. The invention also concerns a hypersaline composition of sea water to which either a NaCI-salt, a brine or a blend of sea water salts has been add- ed such that the total salinity of the composition is larger than in sea water and with a safety margin to the fish welfare. The hypersaline composition may comprise fresh water to which brine or a blend of sea water salts has been added. The invention also concerns a method for making the hypersaline composition. The invention concerns further a topical treatment of the fish with the hypersaline composition only. Optionally the treatment com- prises a combination of hypersaline composition and a freshwater bath. The invention concerns optionally to treat the fish in a first bath that may be a freshwater bath, and sub sequently in a second bath that may be a hypersaline bath. The invention concerns op tionally to treat the fish in a first bath that may be a hypersaline bath, and subsequently in a second bath that may be a freshwater bath. The treatment may be carried out in the same receptacle by adding sea water salts to the fresh water to gradually increase the salinity. The invention also concerns use of a carefully selected range of hypersaline compositions combined with a carefully selected treatment time. In particular, the hyper saline composition is safe to the treated fish. Even more in particular, the combination of the hypersaline composition and the treatment time is safe to the treated fish. The combi- nation of the hypersaline composition, the treatment time and water temperature is safe to the treated fish. Sea lice is a well-known parasitic problem in fish farming, especially in farming of Atlantic salmon in Norway, Scotland, Ireland, Faroes, Canada and Chile. There are several spe cies of the sea lice. Especially important in the Atlantic is the species Lepeophtheirus salmonis. Several treatment methods are known for treatment of sea lice:

Bath treatment: organophosphates, pyrethroids and hydrogen peroxide and fresh water In-feed treatment: ivermectins and acylureas

In addition it is known to use so called cleaner fish which will pick sea lice from the skin of infected fish. Sea lice have over the years built resistance and / or tolerance towards several of the known treatments, especially against several of the bath treatment therapeutics and in- feed therapeutics.

There is a need for new active components against sea lice. In addition to be an effective therapeutic, there are environmental constraints to consider in the choice of the active compound. The commercial value of each individual (fish) is relatively low, which means that price of the active compound is an issue.

The therapeutic margin must be satisfactory. Although the value of each individual is rela tively low, the number of individuals in each pen is large. The total commercial value of the population within one pen is therefore considerable. Treatment of farmed fish is a flock treatment either as a bath treatment or as an in-feed treatment.

Another ectoparasite that affects farmed fish is an amoeba causing the disease Amoebic Gill Disease. The causative agent is Paramoeba perurans. This amoeba infects several different species of marine fish, both wild fish and farmed fish. This includes sea bream, turbot, ayu and mackerel. Patent application WO 2017/123096 discloses a method and device for removing para sites from anadromous fish. A first container is provided with freshwater and a second container is provided with brine having a salinity higher than sea water. The fish is guided from a net cage to the first container and the fish is kept there for a first period. Then, the fish is transferred from the first container to the second container and the fish is kept there for a second period. Thereafter the fish is returned to the net cage. The application dis closes that this treatment can be performed in the opposite order, i.e. first a saline bath followed by a freshwater bath. WO 2017/123096 discloses further that the fish stay in each container for at least one hour such as from one hour to ten hours. In working exam ples WO 2017/123096 discloses to use a brine having a salinity of 62 - 66 g/l. Best effect was observed by first bathing the fish for four hours in freshwater followed by bathing for one hour in brine and repeating this sequence once. A reduction of 100% of sea lice was reported.

Patent application WO 2017/150988 discloses to add a potassium compound, such as potassium chloride to sea water to make up a treatment solution. The fish were exposed to the solution for up to five hours. Only a small portion of the sea lice had fallen off after one hour.

The invention has for its object to remedy or to reduce at least one of the drawbacks of the prior art, or at least provide a useful alternative to prior art.

The object is achieved through features, which are specified in the description below and in the claims that follow.

In this context, sea water is used in its ordinary meaning, and defined as a water with a salinity from 20 to 40 ppt. The ratios of different ions / salts in the sea water are assumed to be constant. Sea water salts are defined as a mixture of salts made up of the dominant salts found in sea water and at inclusion levels of the different salts that correspond to the ratios found in sea water. Commercially available sea water salt blends are known as in stant ocean salt. Hypersaline sea water is a water with a salinity above 40 ppt. A brine is made by concentration of sea water. The brine may be produced by a reverse osmosis process. The ratios of different ions / salts in the brine are assumed to be like the ratios in sea water, i.e. no selective removal or concentration of any ions /salts. A brine is in this context regarded as a sea water salt solution.

The inventors have found that a bath treatment with hypersaline composition makes at least the preadult and adult stages of the sea lice to drop of the fish after some time of exposure. The preadult and adult stages are the motile stages of sea lice.

The hypersaline composition is in one embodiment made up by adding NaCI salt, such as undried vacuum salt, to either sea water of ordinary salinity and composition to make a NaCI solution, or to fresh water to make a NaCI solution, and then add the NaCI solution to sea water of ordinary salinity and composition. In another embodiment the hypersaline composition is made up by adding a brine to the ordinary sea water. Hypersaline sea water according to the invention may be filled into a tank of a well boat. In an alternative embodiment of the invention, the hypersaline sea water may be filled into a closed cage floating in the sea. The closed cage may have a rigid wall. The closed cage may have a flexible wall. Bath treatment or topical treatment of fish in a treatment recep tacle on board a well boat or within a treatment receptacle formed by a closed cage is known to the skilled person. The skilled person will know how to administer fish into the treatment receptacle, and how to administer the fish out of the treatment receptacle. The skilled person will also know how to observe the fish during the treatment and make prop er action if the fish show sign of any discomfort.

In a first aspect the invention relates more particularly to a hypersaline composition for use in a therapeutic, topical treatment of a fish infected with an ectoparasite and said treatment is safe to fish welfare,

where the hypersaline composition comprises one of:

- sea water salts and freshwater;

- sea water salts and sea water; and

- a NaCI solution and sea water,

and the total salinity of the hypersaline composition is in the range from and including 50 ppt and up to and including 58 ppt, and

where the fish is treated for a duration in the time interval from and including 30 minutes up to and including 60 minutes.

The total salinity of the hypersaline composition may be in the range from and including 50 ppt and up to and including 60 ppt, such as from and including 50 ppt and up to and including 58 ppt, such as from and including 50 ppt and up to and including 57 ppt, such as from and including 50 ppt and up to and including 55 ppt. The total salinity of the com position may be in the range from and including 55 ppt and up to and including 60 ppt, such as from and including 55 ppt and up to and including 58 ppt, such as from and in cluding 55 ppt and up to and including 57 ppt. The total salinity of the composition may be in the range from and including 57 ppt and up to and including 60 ppt. Duration of treat ment in the hypersaline composition may be in the time interval from and including 30 minutes up to and including 50 minutes, such as from and including 30 minutes up to and including 40 minutes. Duration of treatment time in the hypersaline composition is meas ured from the time the salinity of the hypersaline composition meets the targeted salinity. The hypersaline composition may be combined with a freshwater bath treatment of the fish in one of the sequences A) and B):

A) transfer of the fish from a first sea water container to a first receptacle containing a so lution consisting of sea water, increase the salinity of the solution in the first receptacle by adding one of a sea water salt solution and a NaCI solution to make the targeted hyper saline composition, keep the fish in the hypersaline composition for a duration in the time interval from and including 30 minutes up to and including 60 minutes, transfer of the fish to a second receptacle containing fresh water, keep the fish in the fresh water for a dura tion in the time interval from and including 30 minutes up to and including 60 minutes, and transfer of the fish to a second sea water container, where the second sea water container may be the same as the first sea water container;

B) transfer of the fish from a first sea water container to a first receptacle containing a so lution consisting of fresh water, keep the fish in the solution for a duration in the time inter val from and including 30 minutes up to and including 60 minutes, increase the salinity of the solution in the first receptacle by adding one of a sea water salt solution and a NaCI solution to make the targeted hypersaline composition, keep the fish in the hypersaline composition for a duration in the time interval from and including 30 minutes up to and including 60 minutes, and transfer of the fish to a second sea water container, where the second sea water container may be the same as the first sea water container.

Duration of treatment in the fresh water may be from and including 30 minutes up to and including 50 minutes, such as from and including 30 minutes up to and including 40 minutes.

The fish may be a salmonoid fish. The fish may be Atlantic salmon ( Salmo salar). The fish may be Rainbow trout ( Oncorhynchus mykiss). The fish may be a Pacific salmon ( On - corhynchus spp.). The ectoparasite may be a crustacean ectoparasite. The crustacean ectoparasite may be a member of the family Caligidae. The crustacean ectoparasite may be a member of the genus Lepeophtheirus. The crustacean ectoparasite may be a mem ber of the genus Caligus.

The ectoparasite may be an amoeba. The amoeba may be the species Paramoeba perurans. This amoeba infects several different species of marine fish, both wild fish and farmed fish. This includes sea bream, turbot, ayu and mackerel in addition to salmonoid fish. In a second aspect the invention relates more particularly to a method for making the hypersaline composition as described above. The hypersaline composition is made by the steps:

a) choose one of a first starting liquid and a second starting liquid, said first starting liquid comprises fresh water and said second starting liquid comprises natural sea water;

b) make one of a first hypersaline master batch and a second hypersaline master batch, said first hypersaline master batch is one of brine, dry sea water salt blend dissolved in fresh water and dry sea water salt blend dissolved in natural sea water, and said second hypersaline master batch is dry NaCI dissolved in natural sea water;

and one of step c) and d), where

c) make the hypersaline composition by pouring the first hypersaline master batch into one of the first starting liquid and the second starting liquid until a target salinity is achieved, and

d) make the hypersaline composition by pouring the second hypersaline master batch into the second starting liquid until a target salinity is achieved.

The brine may be produced by a reverse osmosis process. The brine may be of a salinity between 100 and 150 ppt.

The dry sea water salt blend may be a blend of salts in the ratios found in natural sea wa ter.

The target salinity of the hypersaline composition may be in the range from and including 50 ppt and up to and including 60 ppt, such as from and including 50 ppt and up to and including 58 ppt, such as from and including 50 ppt and up to and including 57 ppt, such as from and including 50 ppt and up to and including 55 ppt. The target salinity of the composition may be in the range from and including 55 ppt and up to and including 60 ppt, such as from and including 55 ppt and up to and including 58 ppt, such as from and in cluding 55 ppt and up to and including 57 ppt. The target salinity of the composition may be in the range from and including 57 ppt and up to and including 60 ppt.

The reverse osmosis process may be carried out on board a vessel and the brine may be collected in a receptacle prior to mixing with sea water or mixing with fresh water.

The vessel may be a well boat. Sea water may be filled in at least one of the well boat’s tanks and the brine may be transported from the receptacle to the at least one tank. In another embodiment the brine is transported from the reverse osmosis apparatus to at least one tank of a well boat and mixed with sea water in the at least one tank. Example 1

In vitro bioassav

Adult female, adult male and preadult sea lice (L salmonis) were collected from Atlantic salmon in a commercial fish farm. For each treatment sea lice were exposed to the treat- ment condition.

Table 1 Moribund sea lice (%) after exposure to different solutions

Exposure time (min)

Solution 30 60 Sea water ΊG 0

Fresh water 68 88 Hypersaline (40 ppt) 0 0

Hypersaline (50 ppt) 14 67 Hypersaline (57 ppt) 86 98

Table 2 Moribund sea lice (%) after exposure to a combination of different solutions

Second exposure

Exposure time (min)

First exposure Salinity (ppt) 30 60

Freshwater (30 min) 40 12 ~

50 62 90

100

Freshwater 7Ϊ

98.5

57 100

Example 2

In vitro bioassav

Mixed sex adult sea lice were collected from a commercial aquaculture site and placed in to 36 modified 50 ml capacity falcon tubes, which had multiple 2mm diameter drilled holes. Tubes were held vertically in a rack fully submerged in sea water (30ppt) which was kept on ice to maintain a temperature of 10-14°C during collection. When several lice had been placed into a tube, a lid was placed on it until all tubes were deemed to have suffi cient lice numbers. At this point tubes were shaken in sea water and lids removed so un bound lice were not in any tube. Numbers of bound sea lice were counted in tubes prior to being submerged into designated salinities for allocated length of time. Each salinity x time combination comprised of three replicate tubes. Time of assessment was the end point, with tubes which were shaken prior to the counting of bound lice then placed into sea water (30ppt). Temperature was maintained during bioassays at 12 (±1) °C. Two as- says were performed using SW (30 ppt) control, 45 ppt, 50 ppt and 55 ppt with 15, 30- and 60-minute immersion times. A third assay was performed using SW (30 ppt), 50 ppt, 55 ppt and 60 ppt with 15, 30- and 60-minute immersion times.

Numbers of lice in each tube that were knocked down were used to calculate percentage of initial tube population still attached for each. All hyper-saline treatments were created from the mixing of 25 ppt salt water well water and supplementation to desired salinity through the addition of instant ocean salt.

Table 3 Mean percent attached (unaffected) sea lice (%) after exposure to different saline solutions

Exposure time (min)

Solution 15 30 60

Sea water (30 ppt) (1^st assay) 100 93 57

Hypersaline (45 ppt) (1^st assay) 80 67 92

Hypersaline (50 ppt) (1^st assay) 72 13 18

Hypersaline (55 ppt) (1^st assay) 28 0 0

Sea water (30 pptj (2^nd assay) 87 96 92

Hypersaline (45 ppt) (2^nd assay) 88 83 68

Hypersaline (50 ppt) (2^nd assay) 81 72 18

Hypersaline (55 ppt) (2^nd assay) 55 19 0

Sea water (30 pptj (3^rd assay) 98 91 88

Hypersaline (50 ppt) (3^rd assay) 76 40 12

Hypersaline (55 ppt) (3^rd assay) 74 5 1

Hypersaline (60 ppt) (3^rd assay) 9 2 0

The two in vitro studies show that ordinary sea water has a small effect on sea lice. This is as expected as sea lice is fully adapted to live in sea water. Any observed effect is due to the experimental set up. It is further observed that hypersaline water of 40 ppt and 45 ppt has only a minor effect within the observation period up to 60 minutes. It is also observed that an immersion time of 15 minutes appear to be too short to obtain a reliable reduction in the number of sea lice that are able to attach themselves to a wall. Example 3

In vivo study

Part A

A hypersaline master batch solution was made by mixing a commercially available marine salt composition (NaCI 66.1 %, MgS0₄16.3%, MgCI₂ 12.7%, CaCI₂ 3.3%, KCI 1.6%) with out any anti-caking agents with fresh water in a mixing vessel. Final salinity was >100ppt.

First and second plastic tanks of 1 m³ were used as treatment receptacles. Each group of fish comprised ten healthy Atlantic salmon ( Salmo sa!ar). The fish had no history of par ticular illnesses and were showing no signs of diseases. In particular there were no signs of gills diseases. Average fish weight was 5.5 kg.

The fish were naturally infected by sea lice. On average each fish was infected by 4.9 females with egg strings (i.e. gravid females), 4.7 adult female, 5.3 adult male, 10.6 prea dults. Chalimus stages were not counted.

All treatments were done in triplicate.

Atlantic salmon (n=10) were gently transferred with a hand net to the first plastic tank / first treatment receptacle containing sea water. Salinity in the first plastic tank was gradually increased by pouring hypersaline solution from the master batch slowly in discrete water jets from the mixing vessel. Salinity in the first tank was measured by a refractometer. Salinity was increased until a target level of 60 ppt was achieved. The Atlantic salmon were exposed to the 60 ppt hypersaline solution for one hour. Thereafter the Atlantic salmon were gently transferred with a hand net from the first plastic tank to the second plastic tank / second treatment receptacle. The second plastic tank contained fresh water. The Atlantic salmon were exposed to fresh water for one hour. Finally, the Atlantic salmon were gently transferred with a hand net to a holding vessel where the Atlantic salmon were closely monitored for mortality post treatment.

A control group of Atlantic salmon (n=10) were gently transferred with a hand net from a pen floating in sea water to the first plastic tank / first treatment receptacle containing sea water. The Atlantic salmon were exposed to sea water for one hour in the first tank.

Thereafter the Atlantic salmon were gently transferred with a hand net from the first plastic tank to the second plastic tank / second treatment receptacle. The second plastic tank contained sea water. The Atlantic salmon were exposed to sea water for one hour in the second tank. Finally, the Atlantic salmon were gently transferred with a hand net to a hold ing vessel where the Atlantic salmon were closely monitored for mortality post treatment. Table 4 Clearance (reduction in %) 60 ppt / 1 h bath followed by freshwater / 1h bath

Gravid Adult females Adult males Preadults

Replicate #1 47 28 36 91

Replicate #2 57 60 74 68

Replicate #3 69 62 79 67

Part B

Part B was performed similar to Part A. The fish were from the same group and had the same infectious load. The hypersaline master batch solution was made up as described in Part A.

Atlantic salmon (n=10) were gently transferred with a hand net to the first plastic tank / first treatment receptacle containing freshwater. The Atlantic salmon were exposed to fresh water for one hour. Thereafter salinity in the first plastic tank was gradually increased by pouring hypersaline master batch solution slowly in discrete water jets from the mixing vessel. Salinity in the first tank was measured by a refractometer. Salinity was increased until the target level of 60 ppt was achieved. The Atlantic salmon were exposed to the 60 ppt solution for one hour. Finally, the Atlantic salmon were gently transferred with a hand net to a holding vessel where the Atlantic salmon were closely monitored for mortality post treatment.

Table 5 Clearance (reduction in %) freshwater / 1h bath followed by 60 ppt / 1 h bath

Gravid Adult females Adult males Preadults

Replicate #1 69 60 89 92

Replicate #2 71 70 76 80

Replicate #3 51 66 83 86

Table 6 Average clearance from Part A and Part B

Gravid Adult females Adult males Preadults

Part A 58 50 63 75

Part B 64 65 83 86

Control test 67 15 57 48

As seen from Table 4, the control test shows that sea lice are effectively removed by the handling procedure. However, it should be noted that fish becomes slower and easier to be caught (re-captured) when they have been exposed to 60 ppt salinity for one hour. In contrast the fish at the equivalent procedural step in the control group are active when re captured. By this, probably more sea lice would detach from the Atlantic salmon during the capture than they would do on treatment.

It was observed that the fish behaved calmly during the periods of gradually and slowly increasing the salinity of the treatment to the intended 60 ppt solution. This was observed for the gradual increase in salinity from fresh water to 60 ppt salinity, and from sea water to 60 ppt salinity.

Example 4

Animal safety study

This study investigated the safety and welfare impacts of administering one-hour hyper saline treatments at either 55 ppt, 57 ppt, and 60 ppt using both ca. 1500g and <150g Atlantic salmon held in 5°C and 15°C water temperature.

It was found that a behavioral assessment scoring system was a good indicator of animal safety during a hypersaline bath treatment regime. Behavioral assessment was evaluated according to“activity”,“positioning” and“orientation”. Scoring was according to table 7.

Table 7 Behavioral assessment scoring system

Score Activity Positioning Orientation

Calm Throughout water Normal

0

column

< 50% Population display < 20% population on

1 < 50% tilting

ing increased activity bottom

³ 50% Population display 20-50% population on ³ 50% population

2

ing increased activity bottom tilting

< 50% Population display >50% population on <50% laying on

3

ing erratic activity bottom flanks

³ 50% Population display ³ 50% population

4

ing erratic activity laying on flanks

Orientation scoring, i.e. loss of balance, was found to be the best behavioural indicator of stress during treatments, where fish will begin tilting in the water column before observa- tions of fish lying on their flanks occurred.

Fish of an appropriate size were distributed across six tanks (30 fish per tank) with each of three treatment groups being represented in duplicate. After a minimum of seven days acclimation, feed was withheld for 48 hours prior to welfare assessment. During immer sion in hypersaline water, behaviour of populations was monitored as stipulated in table 7. Whole tank populations were immersed in designated treatments and after one hour re housed in original host tanks. Behavioural assessments were executed and recorded every 10 minutes during immersion bath, commencing after 10 minutes of the last fish entering the bath. Assessments monitored population activity, positioning, and orientation using a semi-quantitative scoring system as shown in table 7.

Table 8 Observed orientation scores during hypersaline immersion of Atlantic salmon

Observation time (min)

Fish size (g) Temp (°C) Salinity (ppt) ^“^10 20 30 40 50 60^~~

1500 15 55 0 05 05 0 15 Ϊ

57 1.5 1.5 3 3 3 3¹

60 0 1.5 2 2 3 3¹

1000 5 55 0 0 0 O 0 0 ^{~ ~ ~}

57 0 0 0 0.5 1 1^a

60 0 0.5 1 2.5 2.5 3⁴

57 0 0 0 0 0 0.5

60 0 3 4 † † †

80 5 55 0 0 0 O 0 0 ^{~ ~ ~}

57 0.5 0.5 0 0 0 0

60 1 1 1 1 1 1

¹0ne dead fish during immersion period

⁴Four dead fishes during immersion period

aOne moribund fish after immersion period

†AII fishes dead

The effects of one-hour hypersaline treatments on Atlantic salmon were dependent on sampling time, water temperature, fish size and treatment duration. These variables, along with time post-smolt, i.e. small fish, and salt concentration will be important consid erations for treatment administration and post- treatment monitoring and handling in the field. Overall, hypersaline treatments of 57 ppt for 1 hr are efficacious and can be adminis tered safely under certain guidelines.

Throughout all phases, loss of balance (i.e. orientation) was the best predictor of physio logical stress and increased with treatment duration. Although not directly comparable, orientation scores were generally higher in warm water when compared to cold water treatments, coinciding with higher rates of mortality (table 8). Loss of orientation was therefore the most important marker for monitoring treatment safety and recovery. When a control bath (25 ppt) was used, there were no observations of anomalous orientation which suggests that these observations are due to hypersaline stress alone and not fish handling. Conversely, scores for positioning in the water column and level of salmon activ- ity are not likely to be useful markers for field application due to the effects of handling and variability, respectively. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodi ments without departing from the scope of the appended claims. In the claims, any refer ence signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

C l a i m s

1. Hypersaline composition for use in a therapeutic, topical treatment of a fish in fected with an ectoparasite and said treatment is safe to fish welfare,

where the hypersaline composition comprises one of:

- sea water salts and freshwater;

- sea water salts and sea water; and

- a NaCI solution and sea water,

and the total salinity of the hypersaline composition is in the range from and in cluding 50 ppt and up to and including 58 ppt, and

2. Hypersaline composition according to claim 1 , where the hypersaline composition is combined with a freshwater bath treatment of the fish in one of the sequences A) and B):

A) transfer of the fish from a first sea water container to a first receptacle contain ing a solution consisting of sea water, increase the salinity of the solution in the first receptacle by adding one of a sea water salt solution and a NaCI solution to make the targeted hypersaline composition, keep the fish in the hypersaline composition for a duration in the time interval from and including 30 minutes up to and including 60 minutes, transfer of the fish to a second receptacle containing fresh water, keep the fish in the fresh water for a duration in the time interval from and including 30 minutes up to and including 60 minutes, and transfer of the fish to a second sea water container, where the second sea water container may be the same as the first sea water container;

B) transfer of the fish from a first sea water container to a first receptacle contain ing a solution consisting of fresh water, keep the fish in the fresh water for a dura tion in the time interval from and including 30 minutes up to and including 60 minutes, increase the salinity of the solution in the first receptacle by adding one of a sea water salt solution and a NaCI solution to make the targeted hypersaline composition, keep the fish in the hypersaline composition for a duration in the time interval from and including 30 minutes up to and including 60 minutes, and transfer of the fish to a second sea water container, where the second sea water container may be the same as the first sea water container.

3. Composition according to claim 1 , where the fish is a salmonoid fish.

4. Composition according to claim 1 , where the ectoparasite is a crustacean ecto parasite.

5. Composition according to claim 4, where the crustacean ectoparasite is a mem ber of the family Caligidae.

6. Composition according to claim 1 , where the ectoparasite is an amoeba.

7. Method for making the hypersaline composition according to claim 1 ,

c h a r a c t e r i s e d i n that the hypersaline composition is made by the steps:

a) choose one of a first starting liquid and a second starting liquid, said first start ing liquid comprises fresh water and said second starting liquid comprises natural sea water;

b) make one of a first hypersaline master batch and a second hypersaline master batch, said first hypersaline master batch is one of brine, dry sea water salt blend dissolved in fresh water and dry sea water salt blend dissolved in natural sea wa ter, and said second hypersaline master batch is dry NaCI dissolved in natural sea water;

and one of step c) and d), where

c) make the hypersaline composition by pouring the first hypersaline master batch into one of the first starting liquid and the second starting liquid until a tar get salinity is achieved, and

8. The method according to claim 7, wherein the brine is produced by a reverse osmosis process.

9. The method according to claim 7, wherein the dry sea water salt blend is a blend of salts in the ratios found in natural sea water.

10. The method according to claim 7, wherein the target salinity is from and including 50 ppt and up to and including 58 ppt.