Fish farming is the practice of raising fish for commercial gain, usually food, in semi-closed or closed environments on land or at sea, this is the most common form of aquaculture.[13, 14]. In Norway aquaculture is an important and growing industry, in 2019 the industry generated 72 billion Nok from sale of slaugthered fish, of which 93.9% where salmon. In addition to that, the export of fish accounts for 11.4% of total Norwegian exports with a value of 104 Billion including wild catch fisheries. Globally the fish farming market size is growing rapidly with an 4.77% compound annual growth rate, and is expected to reach 376.485 billion USD by 2025 . While fish consumption is growing rapidly worldwide, the over-fishing is unfortunately increasing too . The practice of fish farming can potentially alleviate this problem by reducing the amount of wild capture fishing needed. An important factor for any production is efficiency. Currently there are large losses in aquaculture; in Norway the loss in terms of number of fish, is between 15-20% of which death accounts for a large majority . Among the causes of death are parasitic diseases such as lice and Amoebic Gill Disease (AGD). The treatment of a number of diseases also causes a high number of deaths. A good example of treatment causing harm is with salmon lice, where frequent medication has lead to resistance. Making non-medical treatments necessary, these treatments often cause physical harm and stress which can lead to death . The use of medication, chemicals and feed has a negative environmental impact as well . Reducing fish death will also lower the environmental impact since less medication, chemicals and feed would be needed to meet market demands. Out of many aquaculture diseases we have decided to focus our efforts on one - Amoebic Gill Disease (AGD). Though choice may be arbitrary it is one of the many diseases affecting Norwegian salmon farms and other farms around the world. AGD is an increasing problem in Norway, affecting at least 63% of aquaculture facilities in 2014 . AGD is characterized by lethargy, excessive mucus secretion through multi-focal lesions on swollen gill tissue, respiratory distress and fish rising to the water surface . If left untreated, AGD can cause death and massive damage for fish farmers. For example, some reported up to 80% mortality , while in Tasmania peak smolt mortality where 10% per week . Treatments for AGD exist, like fresh-water bath that kills the amoeba by osmotic shock . In addition to that, AGD can be treated with hydrogen peroxide. However, none of these treatments is perfect and often many rounds of treatment is needed depending on severity . The diagnosis of this infection is unfortunately rather slow and relies on gill score  which only detects severe symptoms and often misdiagnoses AGD for other diseases . Furthermore, this approach is not applicable to all species, like rainbow trout and turbot .
To help solve the problem of AGD we want to create an early detection system and produce an antiparasitic compound via synthetic biology.
Early detection is generally beneficial for all ailments and often reduces the amount of treatment required, this is the case with AGD . Our approach to creating an early detection system is by exploiting behavioural changes, we know that behaviour is an important symptom in many fish diseases and it does also occur as the first symptom in some diseases . Even though it's not the first sign of AGD, which is an increase in serum sodium levels , something that would be hard to measure regularly. The reported behavioural indicators are quite extreme, something that makes it an obvious sign to humans, but if the development of these symptoms are continuous, then an automated detection system might pick it up sooner. This would also be true if disease symptoms develop in discrete steps for only a limited number of fish at once, since these fish might be obscured by the rest. While there are many projects working on tracking individual fish and their swimming patterns, our unique approach is to look at collective behaviours.
The current treatments of AGD that are mentioned cause a great deal of stress and potential harm. In our project we want to make an alternative to this treatment. A first step in this direction is to transfer the gene cluster for production of salinomycin, an antiparasitic compound, into E. coli . We hope that this would complement our detection system and provide a less abrasive treatment than the current industry standard.