A device and method for light treatment of live fish in an aquaculture installation

Abstract

A device and method for light treatment of live fish in an aquaculture installation is presented. The device (3) comprises a light source (6) configured to emit light with characteristics suitable for treatment of fish (10) to create a light field (11) in a treatment region in the aquaculture installation, an opto-mechanical device (8) connected to the light source (6), configured to tailor the light properties to shape and / or position the light field (11) in the treatment region, and a control unit (7) connected to the light source (6) and the opto-mechanical device (8). The control unit (7) is configured to control the characteristics of the light and the light field (11) in the treatment region. This device and method eliminate the need for tracking and targeting individual parasites such as sea lice when treating fish in the aquaculture installation.

Description

[0001] A device and method for light treatment of live fish in an aquaculture installation

[0002] The present invention concerns a device and method for light treatment of live fish in an aquaculture installation. .

[0003] Today, the aquaculture business is a huge industry, which is competitive compared to other ways of producing animal derived food. The industry is relatively new and has large growth ambitions in the years to come. Presently, the industry is characterized by manual operations, and the level of precision is low in areas like fish counting, biomass measurement, sea lice counting, disease surveillance, as well as monitoring fish health and growth rate.

[0004] As of today, it is not uncommon to experience a 15-20 % fish loss in a production cycle, and this causes huge economic losses, poor utilization of resources, poor fish food utilization, larger discharge of nutrient salts into the environment, and poor fish well-being (Sommerset I, Wiik-Nielsen J, Moldal T, Oliveira VHS, Svendsen JC, Haukaas A og Brun E. Fiskehelserapporten 2023, Veterinaerinstituttets rapportserie nr. 8a / 2024).

[0005] Fish lice and several contagious diseases are a growing problem for the business. Resistance is a known phenomenon in excessive use of chemicals or drugs on whole populations of a species.

[0006] The treatment regimens of today are largely performed on all the fish in a net cage, which means that up to 200 000 fish get the same treatment. The treatment may be medication, use of chemicals, hot water, fresh water or mechanical treatment. Treatments pose significant welfare risks to fish, with slaughter sometimes being the only option if lice infestation is severe. The consequences are enhanced risk of resistance to the used chemicals, as well as unnecessary large discharge of chemicals and drugs into the environment. Common for all current treatment methods is that they are one-time operations that temporarily reduce lice pressure. However, when lice pressure is high, these methods fail to maintain low levels over time, resulting in the need for multiple treatments and negative effects on wild fish.

[0007] Further, the present treatment methods often involve starving fish, fish concentrating operations, as well as pumping fish into a different net cage or into a tank in a well boat. A fish concentration operation comprises making the available swimming volume for the fish smaller. This is for instance performed by decreasing the volume of the net cages, and thus, increase the density of fish. For instance, this is performed by concentrating the fish in an area for treatment in the net cages, or for concentrating the fish for transfer onto a fish-tank ship using suction hoses or landing nets.

[0008] Generally, a wellboat has an integrated method of concentrating the fish when it is time to unload the live fish off the ship. For example, this may be a bulkhead, which is moveable through the tank in the ship holding the fish. This bulkhead is moved through the tank to force the fish against the part of the tank from which the fish are released.

[0009] NO331345 describes a device and a method for destroying parasites on fish, such as salmon lice on salmon in fish farms. The device comprises a camera communicating with a controlling unit which in turn communicates with a light source which is adapted to fire pulses of point shaped light which is harmful for the parasite in question. The controlling unit controls a system for optical recognition within a defined coordinate system and to detect points that exhibits contrast differences typical for parasites on a fish surface and to trigger a light pulse from the light source when the coordinates for at detected point coincides with the coordinates for the aiming point of the light source.

[0010] However, this method relies on detection, tracking, and targeting of sea lice, which are typically between 1mm and 8mm, and hard to resolve and track in poor water conditions. Also, this requires advanced computer vision & control systems. Furthermore, it is important that such a device reaches all the fish in a cage / pen to prevent fish from infesting each other. Further, the effect of the method is limited to the later stages of lice that can be recognized, thus resulting in limited effect on keeping the lice infestation levels under control.

[0011] The inventors have discovered that it is not necessary to detect each lice on the fish in order to effectively treat the fish and have come up with an alternative solution to the solutions presented in prior art where fish are treated by exposing whole or certain parts of the fish to a light field without knowing where the lice are situated. The object of the invention is thus to provide an efficient system that is able to treat all fish in a gentle manner, and which has the potential of removing all states of lice infestation and where the efficiency of the treatment is increased such that traditional wellboat treatments will not be needed.

[0012] The device and method presented herein makes it possible to identify an area to be treated based on historic records of the whole population, groups of fish or on individual fish. When treating individual fish, the fish ID together with historic observations of lice can for example be used to enhance the probability of targeting areas where most of the lice are likely to be found. Further it is possible to use programmed light field treatments that follow a medical plan for keeping treatment above a level damaging for parasites and below levels that are harmful for the fish using fish ID as feedback

[0013] The object of the invention is achieved by means of the features of the patent claims.

[0014] In one embodiment, a device for light treatment of live fish in an aquaculture installation, comprises:

[0015] - a light source configured to emit light with characteristics suitable for treatment of fish to create a light field in a treatment region in the aquaculture installation,

[0016] - an opto-mechanical device connected to the light source, configured to tailor the light properties to shape and / or position the light field in the treatment region, and

[0017] - a control unit connected to the light source and the opto-mechanical device, configured to control the characteristics of the light and the light field in the treatment region.

[0018] In this description, light source should mean all kinds of light sources that are able to emit light with characteristics suitable for treatment of fish. The light source may be a laser, such as a pulsed laser or continuous laser, or other kind of light source, and the light may be visible light or other wavelengths that are suitable for the purpose.

[0019] In this description, the term an opto-mechanical device is meant to include any kind of means that can cause the light from a light source to be emitted at different angles, i.e. direction of the emitted light can change direction / move, continuously or in steps or intermittently, for example in a rotary / re volving / rotatable movement, scanning movement, etc. An example is where a beam of light rotates continuously 180 or 360 degrees in the yz-plane in a three-dimensional coordinate system. Another example is to move the light field to targeted regions (x, y, & z). The optomechanical system may for this purpose comprise an actuating system, such as a galvanometer scanner, servo motor, diffractive optical elements, digital hologram, configured to adjust the direction of the light emitted from the light source.

[0020] The opto-mechanical device may further include means that can control other properties of the emitted light such as aperture, intensity, shape, intensity profile, beam convergence or divergence, beam exit direction, & shift. Examples of such devices may include beam expander, apertures, beam blocks, filters, beam splitters, collimator, shutter, autofocus mechanism, beam profiler etc. The control unit comprises a data processor, such as an embedded or standard computing module with processors and may comprise configuration and application storage and communication interfaces to local systems or cloud systems. The control unit can thus control and / or process a number of data in order to control the characteristics of the light and the light field in the treatment region.

[0021] To do this, the control unit can control the opto -mechanical device and the light source in such a way that a light field is created in a treatment region in the aquaculture installation. The treatment region is the region in the aquaculture installation where the treatment finds place, for example, a region where fish is expected to pass regularly.

[0022] In one configuration, the control unit is configured to control the opto-mechanical device to move the light source in two or three dimensions, thereby creating a light field spanning at least a section of the treatment region in the aquaculture installation.

[0023] The device may further comprise a sensor arrangement and a data storage connected to the control unit. As described above, the data storage may be incorporated in the control unit, or a separate data storage may be connected to the control unit. The control unit can then be configured to use measurements from the sensor arrangement to detect the presence of a fish and provide a representation of the fish and the position of the fish in a coordinate system.

[0024] The sensor arrangement may comprise light sensors that calibrates the light based on water absorption and distance to fish to ensure optimal treatment for each fish.

[0025] The sensor arrangement may comprise a second light source, such as a laser, configured for calibration of the measurements.

[0026] The sensor arrangement may comprise one or more cameras and one or more illumination units, for example a second or more light source.

[0027] The one or more cameras may be configured to capture still pictures, video, or a combination of these. The images from the cameras may be processed by the control unit for image processing and other functions such as treatment planning, 3D tracking of fish, ID matching, and ID -based treatment registration.

[0028] The control unit may for example be configured to identify identity features from images captured by the camera or from other sensor device in the sensor arrangement that characterize the individual fish. Identity features can for example be size, weight, colour, shape, surface texture, location, size and distribution of spots, fins, gills, and other distinguishing characteristics. The identity features of each fish can be stored in the data storage to provide an ID for each fish. The control unit may then be configured to control the light source and optomechanical device based on the identity of the fish.

[0029] The sensor arrangement may be configured to detect when light illuminates at least a part of a fish and calculate or otherwise register the position of the light on the fish, i.e. the treatment position on the fish. The treatment position can be stored together with the identity features of the fish for later review or to be used to make a treatment plan for subsequent treatment of each individual fish or for a group of fish.

[0030] The control unit can similarly be configured to detect and calculate the position of at least one eye in the representation of the fish and can then control the light source to avoid the at least one eye. This function means that if using a light with characteristics that may be harmful to the eyes, the control unit can for example shut off or reduce the intensity of the light source when an eye is near the emitted light in the treatment region

[0031] The control unit may be configured to, for each fish:

[0032] - identify health features characterizing a health condition of the individual fish, and

[0033] - store the health features associated with the identity features in the data storage.

[0034] In some configurations, the control unit is configured to control the light source to create a light field with a predetermined shape. This can for example be done by controlling the opto-mechanical device to move the emitted light in a particular pattern or use an opto-mechanical device such as a particular shaped aperture or beam profiler, etc. The shape may be adapted to a particular part of the profile of a fish, or may comprise a non-illuminated spot to protect vulnerable areas such as eyes, etc.

[0035] The control unit may be configured to direct the light from the light source to predetermined positions, based on the representation of the fish and the position of the fish. The predetermined positions can be received from the data storage and may represent areas of the fish where statistically lice are found. For example, statistics may have revealed that more lice may be found near the fish’ gills. The control unit can then process sensor data, for example images from at least one camera, to determine the position of the gills, and the control unit can then control the optomechanical device to direct the light to the area on the fish’ skin near the gills.

[0036] This eliminates the need for tracking and targeting individual parasites such as sea lice when treating fish in the aquaculture installation. Further examples and details of functions and processes of the control unit are described below.

[0037] The device described above have the effect that: only certain areas of the fish are treated that have high probability of infestation uses a light source that is harmful for parasites but does not cause any permanent harm to the fish. a sensor arrangement and control system that calculates the probable treatment areas based on population statistics or on earlier passings of the same fish

[0038] The device and method above also give the possibility of programmed light field treatments that can follow a medical plan for maintaining treatment level which are damaging for parasites but not to the fish

[0039] The invention will now be described by means of examples and by reference to the accompanying figures.

[0040] Figure la- Id illustrate schematically the device and method according to the invention.

[0041] Figure 2a and 2b illustrate two modes for operating the device according to the invention.

[0042] Figure 3a-3d illustrate how the device according to the invention can create different shaped light fields.

[0043] Figure 4 illustrates a fish with vulnerable areas.

[0044] Figure 5 illustrate how fish can be treated by illuminating them with different sections / light “patches” to cover regions of interest, also shows how a fish can be treated in sections over time.

[0045] Figure 6 illustrates how to select areas of fish to be treated

[0046] Figure 7 illustrates different possible light patterns.

[0047] Figure 8 illustrates an embodiment where a sensor arrangement can map vulnerable areas.

[0048] Figure 9 illustrates how to control that the light is focused correctly on the surface of the fish. Figure 10 illustrates three different set-ups for monitoring water quality

[0049] In this description, the examples are focused on treating fish in aquaculture installations, but it should be clear that the device and method described herein also can be used for other purposes or other kinds of treatments.

[0050] Also, parasites such as salmon lice are used as examples of conditions that can be treated, but it should be noted that the systems can be used to treat any organism or other condition that is harmful or uncomfortable for the fish, such as sea lice, worms, fungi, virus, bacteria, etc. The term parasite should thus be understood to comprise all these conditions throughout this description.

[0051] Figure la-lc illustrate a device 3 for light treatment of live fish in an aquaculture installation. The device may for example be installed in an aquaculture installation such as a fish farming pen or net in one or more paths where the fish naturally swim.

[0052] The device 3 comprises light source 6 configured to emit light 6 with characteristics suitable for treatment of fish, to create a light field in a treatment region in the aquaculture installation. The light source may for example be a laser but can in principle be any light source having a wavelength and intensity effectively to kill or render harmless the parasites in question without harming the fish. In other words, the light must have a wavelength and intensity, i.e. sufficient energy, to harm the parasite, but not induce wounds or uncomfortable heating of the skin of the fish. Similarly, if the goal is to treat other conditions than parasites, the characteristics of the light can be adapted to this or may be adjustable.

[0053] The light source may comprise or be connected to an opto-mechanical device or other actuating system, such as a galvanometer scanner, servo motor, diffractive optical elements, digital hologram, etc. to enable the control unit to adjust the direction / po sition and / or the shape of the light emitted from the light source.

[0054] Device 3 further may comprise or be connected to a control unit 7 connected to the light source. Control unit 7 is configured to control the characteristics of the light source 6 and the opto-mechanical device, for thereby controlling the characteristics of the light and the light field emitted from the light source. The control unit 7 may also comprise or be connected to a data storage, and possibly also other accessories.

[0055] In figure la, light source 6 is movable to emit light in two dimensions x, y, spanning a treatment area A in the aquaculture installation. This is done by the light source emitting a light beam which is scanned an angle a. The light beam may be a collimated beam from a laser, or the light beam has a certain convergence, i.e. the diameter of the light beam decreases to at desired depth or distance z from the optical aperture in the light source from which the beam emerges. In figure la, the moving light source 6 creates a light field in form of a “light wall” 4 with a thickness D and extending a height H a length L from the optical aperture 8 in the light source 6. When the fish swims through the light wall, all parts of the fish are treated with the light.

[0056] The device 3 may further comprise a sensor arrangement 1 connected to the control unit. The sensor arrangement may be a camera configured to monitor the treatment area A, but also other sensors may be employed, such as temperature sensors, distance sensors, other water quality sensors, either as an addition or replacing the camera. Figure lb illustrates a camera 1 arranged in an aquaculture installation such that the camera can capture pictures or film of fish 10 in the aquaculture installation, such as a fish pen. The camera 1 has a field of view 2 which defines the region where images can be captured. The images from the camera can for example be used to detect the presence of a fish 10 when it is present within the field of view of the camera. The camera can capture an image, and the control unit uses the image data to provide a representation of the fish and calculate the position of the fish in a coordinate system. The control unit can also be configured to identify individual fish by identifying identity features that characterize individual fish in the image or in the representation of the fish. The identity and identity features of each fish, as well as the representation and position of the fish can be stored in the data storage.

[0057] Figure 1c and Id illustrates an embodiment where device 3 comprises a camera 1 connected to the control unit. The camera 1 has in this example a field of view 2 that is larger than the extension of the light field 11 illuminated by the light emitted from the light source 6. In the embodiment of figure 1c, the camera may be used for example to detect and calculate the position of at least one eye 12 of the fish 10, i.e. the control unit can use the representation of the fish to calculate the eye position, and then use this to control the light source to avoid the at least one eye. Similarly, other vulnerable parts of the fish may be detected, and the light source controlled to avoid such parts. This will prevent the fish from being exposed to harmful light. In figure Id, another embodiment is illustrated, which comprises two devices 3 for light treatment of live fish in an aquaculture installation, each device comprising a camera 1 as described above. In this embodiment, each device is directed to opposite sides of the treatment area, so that both sides of the fish can be viewed and treated simultaneously.

[0058] There may be other configurations which use more or fewer devices in order to cover all the volume of interest in a fish pen or other aquaculture installation. Alternatively, to emitting light from the light source 6 as a “wall” as illustrated in figure 1, other kinds of light fields created by the emitted light may be produced, for example by moving the light source in different pattern, or by shaping the optical aperture in a particular shape. Figure 2a illustrates how a whole fish 10 can be treated by the light field 11 as illustrated in figure 1. The fish 10 swim through the light field 11 and thus the whole body is illuminated section by section, thus treating the whole fish 10.

[0059] In figure 2b, the light field emitted from the light source 6 is controlled to be shaped to cover at least sections of the fish that is to be treated. The shaping of the light field can be done by moving the light source in a predetermined pattern (e.g. by using a galvo scanner or other means), to cover the shape of the fish to be illuminated, or the light source may comprise an optical element arranged at the optical aperture. The optical element can be static (e.g. diffractive optical element) or dynamic (e.g. Liquid crystal on silicon LCOS), i.e. it may be configured to change the shape of the illuminated light field. Both embodiments of figure 2a and 2b can be combined with a sensor arrangement as discussed above, for example a camera, to enable the control unit to control the light source to avoid vulnerable areas of the fish, such as eyes, wounds, etc. In figure 2a, when an eye 12 is detected, the light source can be turned off when the eye 12 is within the illuminated field 4. In figure 2b, the illuminated light field 11 is shaped so that the eye 12 is without light.

[0060] Figure 3a-3d illustrate two embodiments of the device for light treatment of live fish in an aquaculture installation where the opto-mechanical device is utilized to create different shaped light fields.

[0061] In figure 3a an eye 12 is detected by the camera and the position of the eye 12 is then determined by the control unit. When the fish 10 swims through the light field 11, or the light field is created by scanning a volume which comprises the fish, the control unit will turn off the light at the position of the eye 12.

[0062] In figure 3b, there is illustrated that the light field is controlled to expose selected parts of the fish 10 only. The light source is moved to scan the selected parts, or light field with a shape corresponding to the selected parts are created at the selected positions at the fish.

[0063] Figure 3c and-3d illustrate further examples of using a camera to avoid illuminating an eye of the fish with the treatment light. In these examples, the camera can also be moved by using an actuating device, or a camera with large viewing angle may be used and the position of the eye is calculated repeatedly, to follow the position of the eye. This method also can be used to calculate the direction and speed for the movement of the fish, which in turn can be used to ensure that the light field is directed at the correct, intended position at the fish and with the correct energy.

[0064] Figure 4 illustrates a fish 40 with vulnerable areas 41, 42, 43, such as wounds. In this case, the light field 44 illuminates most of the body of the fish 40, but avoids the vulnerable areas 41, 42, 43 and the eye portion 12.

[0065] In all the examples described in this description, when using a camera and identifying individual fish as described above, the control unit can be configured to control the light source based on the identity of the fish.

[0066] There may be a set of rules determining when and where to treat the fish. Such rules may be that each fish is only treated every 14 days, or more often. The rules may also be more individual based. For example, it may be advantageous to treat younger fish or smaller fish less frequently than older or larger fish, or when there are observed increasing amounts of lice in the aquaculture installation or in neighboring installations, it may be advantageous to treat each fish more often.

[0067] In case lice are observed on any one particular fish, it is possible to select that particular fish for area treatment at a later time, without the necessity of determining the exact position of the lice.

[0068] The sensor arrangement can be configured to detect when light illuminates at least a part of a fish and the treatment position of the light on the fish and store the treatment position of the light together with the identity features of the fish. This information can then be used to determine if the detected fish should be treated at this time, i.e. activate the light when the fish is detected, or if the light should be turned off for that particular fish at that particular time.

[0069] The control unit may also be configured to identify health features characterizing a health condition of each individual fish and store the health features associated with the identity features in the data storage.

[0070] This can subsequently be used to monitor the health of the fish over time and can be used by the control unit to focus the treatment light at optimal locations on the fish.

[0071] As described above and shown in figure 2b, the control unit can be configured to control the movement of the light source to create a light field with a predetermined shape.

[0072] Figures 5 and 6 illustrate how the fish can be treated by illuminating them with different sections / light “patches” to cover regions of interest. As illustrated in figure 6, the control unit may divide the representation of the fish into sections, and each section may have different prioritization, for example due to the sensitivity of the skin, probability of lice or other wounds, etc.

[0073] The control unit can also be used to direct the light from the light source to predetermined positions / areas where statistically lice are found. These statistics may be common general knowledge or may be based on observations in a specific aquaculture installation over time. For example, when monitoring the health of the fish over time, certain areas on the same or different fish may prove to be more vulnerable to lice than others, and thus the control unit may direct the light source to those areas more often than others. The calculation of areas to be illuminated by the light source is done based on positions found in the representation of the fish and the position of the fish as discussed above.

[0074] In some embodiments, in addition to emit light fields of different shapes, the light source may emit different light patterns. Figure 7 illustrates different possible light patterns that may be employed by the device. The pattern used may be adapted to the individual fish or to the general population or the parasite situation in the aquaculture installation. For example, may a pattern with a larger grid be effective on fully grown lice, but younger and smaller parasites may not be affected. So, if there has been a long time since the fish were last treated, or if operators have observed young lice on the fish in the aquaculture installation, a more fine -meshed pattern may be used.

[0075] As the energy of the light reaching the fish will vary depending on the distance from the light source to the fish and the current quality of water, there may be a calibration function in the device, for example embodied in the control unit.

[0076] Figure 8 illustrates an embodiment where a sensor arrangement as discussed above, for example a camera, can map vulnerable areas such as eyes, wounds, etc. of multiple fish within a defined space, for example within the treatment region. The sensor arrangement may comprise one or more sensors in order to cover the complete space / treatment area. In figure 8, as an example, a camera 1 is a camera with wide angle lens, i.e. the camera can capture an image with width D and height E. The control unit can detect the presence of all the fish within this area, provide a representation of the fish and the position of the fish in a coordinate system. The control unit can also analyze the images and the representation of the fish and determine the position of the eye in the coordinate system. If several images are captured in a short time period, the direction and speed of the fish may also be calculated. Figure 8a and 8b illustrates two images captured at two different points of time, and it can be seen that the fish has swum a distance to the left from figure 8a to 8b. The eyes are detected in both images, and the control unit can thus control the light source to avoid the area of the eyes, either by turning the light source off, moving it away, shaping the light field to avoid the eyes etc. In this embodiment it is not necessary to identify each fish.

[0077] Figure 9 illustrates how the control unit can ensure that the light is focused correctly on the surface of the fish to ensure that the correct amount of energy is used. If the light is not focused correctly, the power and energy density will be lower, and thus the treatment may not be efficient.

[0078] In picture I of figure 9, the light source emits light as a light beam 92 directed at the skin of a first fish 90, but the fish 90 is too close to the light source, and thus the light beam 92 is out of focus when it arrives the first fish 90. The lack of focus means that the power and energy density of the light when it reaches the fish may be lower than planned, and thus not be as effective as intended. A sensor, for example comprised in the sensor arrangement as described above, or a separate sensor connected to the control unit, detects that the light is out of focus, and the control unit uses the sensor information to determine the how to change the focus of the light emitted from the light source and focuses the light to the correct distance. In picture II of figure 9, the light beam 92 has been focused and the treatment of the first fish 90 is thus effective.

[0079] In picture III of figure 9, the treatment of an area 93 of the first fish is finished and the first fish is on its way out of the treatment region. The second fish 91 has now come completely inside the treatment region, and the control unit directs the light source at the second fish 91, but as this is farther away, the light beam is again out of focus. The control unit uses the sensor information to determine how to change the focus of the light emitted from the light source and focuses the light to the correct distance. In picture IIII of figure 9, the light beam 92 has been refocused and the treatment of the second fish 91 is thus effective.

[0080] Also, the sensors in the sensor arrangement may be used to estimate the water quality, both for calibration purposes, i.e. to adapt the intensity and or other light properties for efficient treatment and for monitoring the environment. Figure 10 illustrates three different set-ups for monitoring water quality by estimating the light absorption of the water between the light source and a sensor. Figure 10a utilizes light reflected by a fish or other obstacle, figure 10b uses a light sensor arranged on the opposite side of the light source in a water volume, and in figure 10c there is a reflective section on the side opposite of the light source, and the sensor is arranged at the same side as the light source. The sensor arrangement may for this purpose comprise a second light source, such as a laser, configured for calibration of the measurements.

[0081] 10

Claims

CLAIMS1. A device for light treatment of live fish in an aquaculture installation, comprising:- a light source configured to emit light with characteristics suitable for treatment of fish to create a light field in a treatment region in the aquaculture installation,- an opto-mechanical device connected to the light source, configured to tailor the light properties to shape and / or position the light field in the treatment region, and- a control unit connected to the light source and the opto-mechanical device, configured to control the characteristics of the light and the light field in the treatment region.

2. A device according to claim 1, wherein the control unit is configured to move the light source in two or three dimensions, creating a light field spanning at least a section of the treatment region in the aquaculture installation.

3. A device according to claim 1 or 2, further comprising a sensor arrangement and a data storage connected to the control unit, and where the control unit is configured to use measurement from the sensor arrangement to detect the presence of a fish and provide a representation of the fish and the position of the fish in a coordinate system.

4. A device according to claim 3, where the sensor arrangement comprises of one or more cameras, one or more illumination units.

5. A device according to one of the claims 1 to 4, where the control unit is configured to control the characteristics of the light and the light field to be harmful for parasites but not harmful for the fish.

6. A device according to one of the claims 3-5, where the control unit is configured to identify identity features characterizing the individual fish and store the identity features of each fish in the data storage.

7. A device according to claim 6, wherein the control unit is configured to control the light source and opto-mechanical device based on the identity of the fish.

8. A device according to one of the claims 3-7, wherein the sensor arrangement is configured to detect when light illuminates at least a part of a fish and the treatment position on the fish and store the treatment position together with the identity features of the fish.

9. A device according to one of the claims 3-8, where the control unit is further configured to detect and calculate the position of at least one eye in the representation of the fish and to control the light source to avoid the at least one eye.

10. A device according to one of the claims 3-9, where the control unit is configured to, for each fish:- identify health features characterizing a health condition of the individual fish, and- store the health features associated with the identity features in the data storage.

11. A device according to one of the previous claims, where the control unit is configured to control the light source to create a light field with a predetermined shape.

12. A device according to one of the claims 3-11, where the control unit is configured to direct the light from the light source to predetermined positions, based on the representation of the fish and the position of the fish, where the predetermined positions are received from the data storage and represent areas of the fish where statistically lice are found based on historic data on populations, groups of fish or in individual fish.

13. A device according to one of the claims 3-12, comprising sensors that calibrates the light based on water absorption and distance to fish to ensure optimal treatment for each fish.

14. A method for light treatment of live fish in an aquaculture installation, comprising:- emitting light with characteristics suitable for treatment of fish in a treatment region in the aquaculture installation to create a light field, where the characteristics of the light and tailoring the shape and / or position of the light field in the treatment region is controlled by a control unit.

15. A method according to claim 14, where the fish and or the section of the fish to be treated are selected based statistical methods and not based on tracking and targeting individual parasites such as sea lice to treat the fish.

16. A method according to claim 14, where the fish and or the section of the fish to be treated are selected based on individual identity features and aquaculture installation’s treatment programs.

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