RU2795233C2 - Fish cage with improved water exchange and breeding conditions - Google Patents

Abstract

FIELD: fish cage.

SUBSTANCE: cage (1) has an upper area (10) and a lower area (19), is made with the possibility of swimming in the water layer (99) and contains a surrounding floating body (11) in the upper area (10) of the cage (1), and the surrounding floating body (11) is made with the possibility of floating on the water surface (90), the body (2) between the upper area (10) and the lower area (19) of the cage (1), and the body (2) is closed in the lower area (19) of the cage (1) and forms the inner part (21) and the outer part (23) and a waterproof wall (5) in the upper region (10), wherein said waterproof wall (5) is attached to the floating body (11) and extends from the water surface (90) down in the water layer (99), while the waterproof wall (5) forms the lower edge region (59). The cage (1) is equipped in its upper area (10) with at least one flow amplifier (4) to create a circular water flow (40) within the waterproof wall (5). The flow amplifier (4) is configured to supply water from the inner part (21) in the upper region (10) of the cage (1). The cage (1) is configured to introduce an upward water flow (49) into the centre of the cage (1) in the lower region (19). A method for creating an upward flow (49) of fresh water within the cage (1) is proposed. Circular water flow 40 forms an ascending central water flow 49.

EFFECT: invention ensures the supply of the cage with fresh water from the environment coming from the bottom area of the cage.

11 cl, 14 dwg

Description

The field of technology to which the invention belongs

The present invention relates to a fish tank. More specifically, the invention relates to a cage partially closed in such a way that at least the upper region of the cage is provided with a watertight wall. According to the invention, the cage is provided with at least one flow enhancer in the upper region. The flow enhancer induces a circular flow that creates an overpressure along the watertight wall, thereby helping to maintain the watertight wall in tension, or possibly pressing the watertight wall against the housing from the outside. According to the invention, the circular flow forms in the center of the cage an area with a lower hydrodynamic pressure than the surrounding hydrodynamic pressure, which creates an upward flow of water in the center of the cage. In the upper and peripheral area of the cage, an excess pressure arises compared to the surrounding hydrodynamic pressure, and water flows out of the cage through holes in this area. The invention also includes regulation of the outflow from the cage by means of a watertight wall with an inwardly protruding rim. By limiting the amount of water pumped through the cage, the energy required to maintain a circular flow in the cage is reduced and energy consumption is reduced. The rim also helps with good circulation for most of the volume in the cage. When the lip is used at the bottom, the circular water flow extends all the way down to the lip. The well-being of the fish in the cage is improved due to the circular water flow, as well as due to the flow of a large amount of fresh water from the area under the cage through the center of the cage.

State of the art

Fish rearing can take place in so-called open cages. An open cage contains a closed hull held afloat by a surrounding floating body. The closed housing may contain a net or seine so that the fish is trapped in the housing and water with dissolved oxygen can pass through it. The hull is closed in the submerged part and protrudes above the water surface due to the so-called jumping net to prevent the fish from leaving the hull. The body is open to air entry, but can be covered with a so-called bird net. The cage is equipped with a mooring system and a power supply system.

Fish rearing can also take place in so-called closed cages. The closed cage contains a watertight wall and a watertight bottom. The waterproof wall and bottom can be made of fabric or rigid material. The rigid material may comprise fiberglass, a laminate, concrete, or a metal such as steel. Water is supplied to the closed system by pumping it from the environment into the closed cage. The closed cage may be provided with a drain hole in the lower region or in the wall.

The disadvantage of open cages is that organisms that can cause disease in fish get into the cage along with the water. This is especially true for the larvae of the parasite - salmon lice. A known method of supplying open cages with so-called anti-lice skirts. This may be a fine-mesh tissue surrounding the cage from the outer side of the floating body and passing in the water column down to a depth where the number of salmon louse larvae is small or they are completely absent. It is also known to use anti-lice skirts made of waterproof material, such as tarpaulins.

In connection with the so-called bath treatment of fish in a cage, it is known that the tarpaulin is stretched around the cage from the outside, and also wholly or partly under the cage, in order to limit the spread of the bath treatment agent as much as possible.

Patent No. 165901 discloses a device for breeding fish in a box submerged in water. The box contains an upper area made of a waterproof material and a lower area with a drain. Fresh water enters the upper area of the box so that a relatively slow downward flow of water occurs in it. Patent No. 341377 discloses a cage with a net body. The skirt surrounds the cage on the outside of the net and extends to the area above the bottom ring. The flow amplifier inside the cage sucks water from the bottom of the skirt and distributes it inside the cage to the upper water masses. The drain from the flow amplifier is directed horizontally and causes the upper water masses to rotate. Patent No. 343,600 discloses a waterproof screen fixed on the inside to the wall of a net in a fish tank. Patent No. 343,181 discloses a cage surrounded in the upper region by a lice skirt to form a semi-enclosed cage. The air-conducting element is located in the area near the lower ring and at a distance from the cage center. Air under pressure is supplied to the air-conducting element, and air bubbles, rising up, create an upward water flow inside the cage.

Disclosure of the essence of the invention

The aim of the invention is to eliminate or reduce at least one of the disadvantages of the prior art, or at least provide a useful alternative to the prior art.

The goal is achieved by the features defined in the following disclosure and in the following claims.

The invention is defined by independent claims. The dependent claims define preferred embodiments of the invention.

In a first aspect, the invention relates more particularly to a fish-breeding cage, wherein the cage forming the upper and lower regions floats in the water column, wherein the cage comprises:

- surrounding floating body in the upper area of the cage, made with the possibility of floating on the water surface; And

- a housing between the upper and lower regions of the cage, closed in the lower region of the cage, while the housing forms the inner and outer parts. The cage comprises a watertight wall attached to the floating body and extending from the water surface down in the water column, the watertight wall forming a lower edge region; and the cage is provided in its upper region with at least one flow enhancer for creating a circular water flow within the watertight wall. The flow amplifier is supplied with water from the interior in the upper area of the cage.

The flow amplifier may contain a water cannon. The water jet can suck water from the inside of the hull. The flow amplifier may include an ejector. The ejector fluid can be taken from the inside of the housing. The flow amplifier may include a propeller. The flow amplifier may include a thruster.

According to the invention, the circular flow within the cage creates in the center of the cage a region with a lower hydrodynamic pressure than the surrounding hydrodynamic pressure. This creates an upward flow of water in the center of the cage. The ascending water flow enters the center of the cage in its lower area. Water flows upwards within the housing and can flow out of holes in the watertight wall when the hydrodynamic pressure on the inside of the watertight wall is higher than on the outside of the cage. Water may leak from holes in the watertight wall in the upper area of the cage.

The housing may contain a network with the possibility of its attachment to the lower edge region. In an alternative embodiment of the invention, the hull may comprise a net capable of being attached to a surrounding floating body such that the watertight wall is located on the inside of the net. The watertight wall may form the interior of the housing in the upper region of the cage. In this embodiment of the invention, the lower edge region may be attached to the network. The advantage of this option is that the fish cannot pass between the watertight wall and the net. The waterproof wall may be located on the outside of the net.

The watertight wall may form a cylindrical region between the upper and lower regions, and the bottom net extends downward in the water column from the lower edge region.

The watertight wall may be provided in the lower edge region with a surrounding ledge protruding inwardly towards the center of the cage. The surrounding ledge may protrude inwards by a quarter of the radius of the cage defined in its upper region. The surrounding ledge may protrude inwards by a third of the radius of the cage defined in its upper region. The surrounding ledge may protrude inwards by half the radius of the cage defined in its upper region. The surrounding ledge may protrude inwards by more than half the radius of the cage defined in its upper region, for example by 2/3, 3/4, 4/5 or even more. The surrounding ledge may protrude inwards only to the extent that there is a sufficient opening for water to enter the ascending water stream in the center of the cage. The edge may slope downward towards the center of the cage. The edge may slope upwards towards the center of the cage. The side can be oriented horizontally.

In the upper area of the wall, the watertight wall may be provided with at least one closable hole for the outflow of water from the upper area of the cage, and the hole may be provided with means to retain fish. Open hole area can be adjustable. The tool may contain a fine mesh network or lattice. In the lower region, the watertight wall may be provided with at least one hole for the outflow of water from the cage. The hole may be provided with means for retaining the fish. Open hole area can be adjustable. The hole may be closed.

In a second aspect, the invention relates to a method for creating an ascending central flow of fresh water inside a housing in a fish tank, the tank forming the upper and lower regions floating in the water column, the tank comprising:

- surrounding floating body in the upper area of the cage, made with the possibility of floating on the water surface; And

- a housing between the upper and lower regions of the cage, closed in its lower region, while the housing forms the inner and outer parts.

The method is different in that

- the cage is provided with a watertight wall attached to the floating body and extending from the water surface downwards in the water column, the watertight wall forming the lower edge region; the cage is provided in its upper region with at least one flow enhancer, which receives water from the inside of the housing to create a circular water flow within the watertight wall;

- circular water flow creates in the center of the cage in its lower area a lower hydrodynamic pressure than the ambient pressure, so that water enters the bottom area of the cage below the edge area and rises up the cage with an ascending central water flow; And

- the circular water flow creates a hydrodynamic pressure on the periphery of the cage that exceeds the ambient pressure, so that water flows out of the cage through an opening in the watertight wall.

The waterproof wall may form the inside of the case in the upper region.

Water can flow out of the cage through a hole in the watertight wall in the upper area of the cage. Water can flow out of the cage through an opening located in the lower edge region of the watertight wall. Water can flow out of the cage through an opening located between the lower edge region of the watertight wall and the floating ring.

Also disclosed is a cage for fish breeding, wherein the cage may form upper and lower regions and float in the water column, wherein the cage may comprise:

- surrounding floating body in the upper area of the cage, made with the possibility of floating on the water surface; And

- a housing between the upper and lower regions of the cage, closed in its lower region, while the housing forms the inner and outer parts. The cage may comprise a watertight wall attached to the floating body and extending from the water surface down into the water column, the watertight wall forming a lower edge region;

the cage is provided in its upper region with at least one flow enhancer for creating a circular water flow within the watertight wall; And

the watertight wall in the lower edge region has a surrounding ledge protruding inward towards the center of the cage. The flow amplifier is supplied with water from the interior in the upper area of the cage.

The waterproof wall may form the inside of the case in the upper region.

The flow amplifier may contain a water cannon. The water jet can suck water from the inside of the hull. The flow amplifier may include an ejector. The ejector fluid can be taken from the inside of the housing. The flow amplifier may include a propeller. The flow amplifier may include a thruster.

The housing may contain a network with the possibility of its attachment to the lower edge region. In an alternative embodiment of the invention, the hull may comprise a net capable of being attached to a surrounding floating body such that the watertight wall is located on the inside of the net. In this embodiment of the invention, the lower edge region may be attached to the network. The advantage of this option is that the fish cannot pass between the watertight wall and the net.

The watertight wall may form a cylindrical region between the upper and lower areas of the cage, and the bottom net extends downward in the water column from the lower edge region.

In the lower edge region, the watertight wall may have a surrounding ledge projecting inward towards the center of the cage. The surrounding ledge may protrude inwards by a quarter of the radius of the cage defined in its upper region. The surrounding ledge may protrude inwards by a third of the radius of the cage defined in its upper region. The surrounding ledge may protrude inwards by half the radius of the cage defined in its upper region. The surrounding ledge may protrude inwards by more than half the radius of the cage defined in its upper region, for example by 2/3, 3/4, 4/5 or even more.

The watertight wall in its upper region may be provided with at least one closable opening for the outflow of water from the upper region of the cage, and the opening may be provided with means for retaining fish. The tool may contain a fine mesh network or lattice. In the region of the lower ring, the watertight wall may be provided with at least one closable opening for the outflow of water from the upper area of the cage, and the opening may be provided with means for retaining fish.

Also disclosed is a fish breeding tank, forming the upper and lower regions and floating in the water column, while the tank contains:

- surrounding floating body in the upper area of the cage, made with the possibility of floating on the water surface; And

- a waterproof wall between the upper and lower areas of the cage; And

- the lower region is waterproof and made in the form of a truncated cone;

- at least one flow enhancer for creating a circular water flow within the watertight wall. The inlet of the cage may be formed from a free edge region at the end of the truncated cone, this inlet may be provided with a first means for retaining fish.

The end of the truncated cone may point downwards in the water column, and the inlet may be provided with a lip projecting upward and enclosing the free edge region so that a mud trough is formed around the inlet.

The end of the truncated cone may point upwards in the water column so that a mud trough is formed on the watertight wall.

In the upper area, the watertight wall may be provided with at least one adjustable hole for water outflow from the upper area of the cage, and the hole may be provided with a second means for retaining fish. The hole may be closed.

In various embodiments of the invention, the watertight wall may comprise fabric. In various embodiments of the invention, the watertight wall may comprise a rigid material. The rigid material may comprise fiberglass, a laminate, concrete, or a metal such as steel. In various embodiments of the invention, the rim may contain fabric. In various embodiments of the invention, the rim may contain a rigid material. The rigid material may comprise fiberglass, a laminate, concrete, or a metal such as steel.

Brief description of the drawings

The following describes examples of preferred embodiments of the invention, illustrated in the accompanying drawings, namely:

In FIG. 1 is a side view of a fish tank according to the prior art;

In FIG. 2 shows a plan view of the cage according to the invention, on the same scale as in figure 1;

In FIG. 3 shows a cross section of a cage according to a first embodiment of the invention;

In FIG. 4 shows an embodiment of the invention shown in FIG. 3;

In FIG. 5 shows a cross section of a cage according to a second embodiment of the invention;

In FIG. 6 shows an embodiment of the invention shown in FIG. 5;

In FIG. 7 shows a cross section of a cage according to a third embodiment of the invention;

In FIG. 8 is a plan view of the same and to the same scale as in FIG. 7 showing horizontal water flow;

In FIG. 9 shows an embodiment of the invention shown in FIG. 7;

In FIG. 10 shows another embodiment of the invention shown in FIG. 7;

In FIG. 11 shows a cross section of a cage according to a fourth embodiment of the invention;

In FIG. 12 shows on the same scale a plan view of the same as in FIG. 10;

In FIG. 13 is a cross section of the cage shown in FIG. 7, with a schematic representation of the vertical water flow; And

In FIG. 14 is a cross section of the cage shown in FIG. 11, with a schematic representation of the vertical water flow, as well as the sedimentation of faeces and uneaten food.

Implementation of the invention

In the drawings, reference numeral 1 denotes a fish tank (not shown). A cage 1 according to the prior art is shown in FIG. 1 and 2. The cage 1 forms an upper region 10 and a lower region 19. The cage 1 is provided with a surrounding floating body 11 floating on the water surface 90 and keeping the cage 1 afloat in the water column 99. The railing 13 protrudes upward from the surrounding floating body 11.

The cage 1 comprises a closed casing 2 forming a fish barrier so that the fish cannot escape from the cage 1. The casing 2 forms an upper area 20 and a bottom area 29, as well as an inner part 21 and an outer part 23. The casing 2 may be made of a net 3. The hull 2 is attached directly to the floating body 11 or to the railing 13, or both directly to the floating body 11 and to the railing 13. The net 3 comprises a bottom net 39 extending downward in the water column 99 and may form a lower hull region 29 2.

The cage 1 includes a surrounding bottom ring 15. The housing 2 is attached to the bottom ring 15 and held in an expanded state by it.

A cage 1 according to the invention is shown in FIG. 3-14. The cage 1 is provided with a flow booster 4 creating a circular, substantially horizontal water flow 40 within the cage 1 (see FIG. 8). The flow booster 4 is shown with a holder 41. The flow booster 4 has a drain 43. The flow booster 4 may include a water jet that draws water from the interior of the housing 2. The flow booster 4 may include an ejector that is supplied with working fluid drawn from the interior of the housing 2. In other embodiments of the invention, the flow enhancer 4 may comprise a propeller or thruster.

In the first embodiment of the invention, the cage 1 comprises a waterproof wall 5 extending down the cage 1 from the floating body 11 in the upper region 10 of the cage 1. The waterproof wall 5 is located on the inside of the upper region 20 of the housing 2 as shown in FIG. 3. The waterproof wall 5 may be fabric. The waterproof wall 5 may be made of a rigid material. The watertight wall 5 is preferably attached to the railing 13 in the upper region 50 so that the upper region 50 of the wall 5 protrudes above the water surface 90.

In FIG. 3, the distance between the net 3 and the waterproof wall 5 is exaggerated to show that the waterproof wall 5 is located on the inside of the upper region 20. The waterproof wall 5 is attached in the lower edge region 59 to the housing 2 so that the fish in the cage 1 cannot pass between the net. 3 and waterproof wall 5.

In FIG. 4 shows a first embodiment of the invention. The watertight wall 5 is located on the inside of the body 2. The watertight wall 5 extends down to the lower ring 15, thus the watertight wall 5 forms the main part of the cylindrical area of the cage 1. The watertight wall 5 is attached in the lower edge region 59 to the body 2 so that the fish in cage 1 cannot pass between net 3 and waterproof wall 5.

In a second embodiment of the invention, the cage 1 comprises a watertight wall 5 extending down the cage 1 from the floating body 11 in the upper region 10 of the cage 1. The watertight wall 5 is part of the upper region 20 of the hull 2 as shown in FIG. 5. The waterproof wall 5 may be fabric. The waterproof wall 5 may be made of a rigid material. The watertight wall 5 is preferably attached to the railing 13 in the upper region 50 so that the upper region 50 of the wall 5 protrudes above the water surface 90. The net 3 is attached to the lower edge region 59 of the wall 5. The net 3 extends from the edge region 59 down into the water column 99, wherein the network 3 forms the lower region 29 of the body 2.

In FIG. 6 shows a second embodiment of the invention. The watertight wall 5 extends down to the bottom ring 15, thus the watertight wall 5 is the main part of the cylindrical area of the cage 1.

In a third embodiment of the invention, the cage 1 comprises a watertight wall 5 extending down the cage 1 from the floating body 11 in the upper region 10 of the cage 1. The watertight wall 5 may be made of fabric. The waterproof wall 5 may be made of a rigid material. The rigid material may comprise fiberglass, a laminate, concrete, or a metal such as steel. In its lower edge region 59, the watertight wall 5 is provided with a surrounding inner collar 6, as shown in FIG. 7 and 8. The collar 6 is attached to the lower edge region 59 of the wall 5 as shown in FIG. 7.

In its upper region 50, the waterproof wall 5 is attached to the floating ring 51. The floating ring 51 is located on the inside of the floating body 11. The floating ring 51 is sized to be more positively buoyant than the floating body 11. This will be explained below.

The watertight wall 5 is provided with at least one opening 53. The drawings show a plurality of openings 53. The opening 53 is provided with a first means 55 for holding the fish in the cage 1 so that the fish cannot escape through the opening 53. The means 55 may comprise a fine mesh net or a grate . The opening 53 can be adjusted, closed or opened with a hatch (not shown) or other tight barrier over the opening 53. The hatch or barrier controls the amount of water that can flow through the opening 53. The openings 53 are located as shown in the lower edge region 59. Alternatively, the holes 53 may be located between the edge region 59 and the floating ring 51. The holes 53 may be located at different heights around the circumference of the wall 5.

The flow booster 4 is not shown in FIGS. 7 and 8, but in this third embodiment of the invention, the cage 1 is provided with at least one flow booster 4.

The watertight wall 5 is an area of the housing 2. In FIG. 7 shows that the wall 5 is part of the upper region 20 of the housing 2. The net 3 is attached to the lower edge region 59.

In the third embodiment of the invention, the wall 5 extends down to the lower ring 15, thus the watertight wall 5 is the main part of the cylindrical area of the cage 1, as shown in FIG. 9. The ledge 6 protrudes inwardly in the lower region 29 of the housing 2. The net 3 is attached to the lower edge region 59 of the wall 5. In FIG. 9 shows that in this embodiment the closable opening 53 is located on the lower ring 15. In FIG. 10 shows that in this embodiment the closable opening 53 is located on the floating ring 51.

In a fourth embodiment (not shown), the cage 1 comprises a watertight wall 5 extending down the cage 1 from the floating body 11 in the upper area 10 of the cage 1. The watertight wall 5 is located on the inside of the top area 20 of the hull 2 in the same manner as shown in fig. 3. The hull 2 is attached to the floating body 11 and/or the railing 13 in the same manner as shown in FIG. 3. The waterproof wall 5 may be fabric. The waterproof wall 5 may be made of a rigid material. In its lower edge region 59, the watertight wall 5 is provided with a surrounding inner collar 6, in the same manner as shown in FIG. 7. The collar 6 is attached to the lower edge region 59 of the wall 5 in the same manner as shown in FIG. 7. In the lower edge region 59, the watertight wall 5 is attached to the housing 2 so that the fish in the cage 1 cannot pass between the net 3 and the watertight wall 5.

In the fourth embodiment (not shown) of the invention, the watertight wall 5 is located on the inside of the housing 2. The watertight wall 5 extends down to the lower ring 15, thus the watertight wall 5 is the main part of the cylindrical area of the cage 1. The watertight wall 5 is attached at the bottom edge area 59 to the body 2 so that the fish in the cage 1 cannot pass between the net 3 and the watertight wall 5. The ledge 6 protrudes inwardly in the lower area 29 of the body 2 as shown in FIG. 9 and 10.

In a fourth embodiment of the invention, the watertight wall 5 extends down to the lower ring 15 and the ledge 6 protrudes inwardly in the lower region 29 of the housing. The collar 6 defines a central opening 61. The central opening 61 has a surrounding frame 63 projecting upwards as shown in FIG. 11. Frame 63 defines a channel 64 through which water can flow. The channel 64 is provided with a second means 65 for holding the fish in the cage 1 so that the fish cannot escape through the channel 64. The second means 65 may comprise a fine mesh or grate.

The upward projecting frame 63 defines a mud trough 7 between the frame 63 and the ledge 6. In this embodiment, the cage 1 is provided with a sump (not shown) and a mud hose 71 between the sump 7 and the sump. In FIG. 14 shows how the faecal matter 73 and food residues 75 descend towards the mud trough 7.

According to the invention, the circular flow 40 forms in the center of the cage 1 a region with a lower hydrodynamic pressure than the surrounding hydrodynamic pressure. This creates an upward water flow 49 at the center of cage 1 as shown in FIG. 13 and 14. The upflow 49 of fresh water enters the center of cage 1 in the lower region 19 through the lower net 39 as shown in FIG. 13 or through the second means 65 as shown in FIG. 14, and water flows out of the holes 53 in the upper region 10 of the cage 1, where the hydrodynamic pressure on the inner side 21 of the wall 5 is higher than on the outer side 23.

The inwardly protruding ledge 6 has the advantage of allowing a circular water flow 40 to be generated around the circumference of the cage with less energy. The water flow 40 in cage 1 is more extended; i.e., the water flow 40 occupies a larger volume of the cage 1 compared to the cases when the flow amplifiers 4 are used in the cage 1 without the edge 6. The well-being of the fish in the cage 1 is improved due to the circular water flow 40 against which the fish will have to swim, and also due to the fact that that the circular water flow 40 forms an ascending central water flow 49 which supplies the cage 1 with fresh water from the environment in the lower region 19 of the cage 1.

It should be noted that all of the above embodiments of the invention are illustrative of the invention, but do not limit it, and many alternative embodiments of the invention can be made by those skilled in the art without departing from the scope of the appended claims. In the claims, the position numbers in parentheses should not be construed as limiting.

The use of the verb "comprise" and its various forms does not exclude the presence of elements or steps that are not mentioned in the claims. The use of an element in the singular does not exclude the presence of several such elements.

The fact that certain features are indicated in mutually different dependent claims does not mean that a combination of these features cannot be used to advantage.

Claims (24)

1. A cage (1) for breeding fish, forming an upper area (10) and a lower area (19), while the cage (1) is made with the possibility of swimming in the water column (99) and contains: - the surrounding floating body (11) in the upper area (10) of the cage (1), and the surrounding floating body (11) is made with the possibility of floating on the water surface (90); - a housing (2) between the upper region (10) and the lower region (19) of the cage (1), wherein the housing (2) is closed in the lower region (19) of the cage (1) and forms the inner part (21) and the outer part (23 ), - and a watertight wall (5) in the upper region (10), wherein said watertight wall (5) is attached to the floating body (11) and extends from the water surface (90) down into the water column (99), and at the same time the watertight wall ( 5) forms the lower edge region (59); characterized in that - the cage (1) is provided in its upper area (10) with at least one flow amplifier (4) to create a circular water flow (40) within the watertight wall (5), - moreover, the flow amplifier (4) is configured to supply water from the inner part (21) in the upper region (10) of the cage (1), - at the same time, the cage (1) is made with the possibility of introducing an upward water flow (49) into the center of the cage (1) in the lower region (19). 2. The cage (1) according to claim 1, in which the housing (2) contains a net (3) attached to the lower edge region (59). 3. The cage (1) according to claim 1, in which the body (2) contains a net (3) attached to the surrounding floating body (11), and a watertight wall (5) is located on the inner side of the net (3). 4. The cage (1) according to claim 1, in which the body (2) contains a net (3) attached to the surrounding floating body (11), and at the same time the watertight wall (5) is located on the outside of the net (3). 5. The cage (1) according to claim 3, in which the lower edge region (59) is attached to the net (3). 6. cage (1) according to any one of paragraphs. 2-5, in which the waterproof wall (5) forms a cylindrical region between the upper region (10) and the lower region (19) of the cage (1), and the bottom net (39) extends downward in the water column (99) from the lower edge region ( 59). 7. The cage (1) according to any one of paragraphs. 1-6, in which the waterproof wall (5) has in the lower edge region (59) a surrounding ledge (6) protruding inward towards the center of the cage (1). 8. The cage (1) according to claim 7, in which the surrounding ledge (6) protrudes inward by a quarter of the radius of the cage (1) defined in the upper area (10) of the cage (1). 9. The cage (1) according to any one of paragraphs. 1-8, in which the waterproof wall (5) is provided in the upper region (50) with at least one closable hole (53) for the outflow of water from the upper region (10) of the cage (1), and the hole (53) is provided with a means (55 ) to keep the fish. 10. A method for creating an ascending central flow (49) of fresh water inside the body (2) in a cage (1) for breeding fish, with the cage (1) forming an upper area (10) and a lower area (19), while the cage (1) floats in the water column (99) and contains: - the surrounding floating body (11) in the upper area (10) of the cage (1), and the surrounding floating body (11) is made with the possibility of floating on the water surface (90); - and a housing (2) between the upper region (10) and the lower region (19) of the cage (1), wherein the housing (2) is closed in its lower region (29) and forms the inner part (21) and the outer part (23), characterized in that - the cage (1) is provided in the upper area (10) with a waterproof wall (5) attached to the floating body (11) and extending from the water surface (90) down in the water column (99), while the waterproof wall (5) forms the bottom edge region (59); - the cage (1) is provided in its upper area (10) with at least one flow amplifier (4), into which water is supplied from the inner part in the upper area (10) of the cage (1) to create a circular water flow (40) within waterproof wall (5); - and the circular water flow (40) creates in the center of the cage (1) in its lower region (19) a lower hydrodynamic pressure than the ambient pressure, so that water enters the lower region (19) of the cage (1) under the edge region ( 59) and rises up the cage (1) in the ascending water stream (49). 11. The method according to claim 10, in which the circular water flow (40) creates a hydrodynamic pressure exceeding the ambient pressure at the periphery of the cage (1), so that water flows out of the cage (1) through an opening (53) in the watertight wall (5 ).

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