Fish feed in Aquaculture

Many pet lovers and aqua­rists know that the same appli­es to ani­mals: „You are what you eat“. The­r­e­fo­re, the food used in fish far­ming plays an important role in the end pro­duct that ends up on the con­su­mer’s pla­te. In recent years, many nega­ti­ve head­lines about harmful feed addi­ti­ves (e.g. eth­oxy­quin) and the unsus­tainable pro­ces­sing of wild-caught fish into fish meal and fish oil have domi­na­ted the press. But mean­while, both manu­fac­tu­r­ers and users of fish feed are rethin­king their approach to envi­ron­men­tal­ly fri­end­ly alter­na­ti­ves. Ther­eby, we deal in this blog post with the ques­ti­ons, which food fish need at all, how you can pay atten­ti­on to a balan­ced nut­ri­ti­on of the ani­mals and how you can pro­mo­te their health, well-being and growth.

First of all, the feed size is cru­cial in aquacul­tu­re. The smal­ler the fish, the smal­ler the pet food should be, so that the fish can absorb and pro­cess the food well. The­r­e­fo­re, the feed in fish far­ming is main­ly fed as dry sub­s­tance in the form of pel­lets or gra­nu­les. The­se are fil­led in 25 kg sacks or in big bags (600 kg) and are then easy to hand­le during trans­port as well as good storable. To ensu­re a balan­ced diet for the fish, fish food con­ta­ins vit­amins and cere­als. In addi­ti­on, fish need a high pro­por­ti­on of pro­te­in in the feed to build mus­cle mass. Most edi­ble fish are car­ni­vor­ous ani­mals. This means they need main­ly ani­mal pro­te­ins in their diet. Up to now, this has been ensu­red pri­ma­ri­ly by using fish meal and oil, which are obtai­ned from cat­ching and pro­ces­sing wild fish. Fish­me­al has a very high pro­te­in con­tent of around 60 per­cent. Howe­ver, the sole use of fish meal and fish oil in feed pro­duc­tion can­not be con­side­red sus­tainable, espe­ci­al­ly sin­ce aquacul­tu­re has been the fas­test gro­wing branch of the glo­bal food indus­try sin­ce 1970. The more fish is to be pro­du­ced, the more has theo­re­ti­cal­ly be caught and pro­ces­sed into feed. This con­sider­a­b­ly redu­ces the wild stocks in the sea. The­r­e­fo­re, the goal is to incre­asing­ly deve­lop sus­tainable feed and to replace the ani­mal parts from end­an­ge­red stocks with other com­pon­ents. But do you know that the fish you buy has been fed sustainably?

Envi­ron­men­tal­ly fri­end­ly fish farms can be reco­gni­zed by the ger­man typi­cal orga­nic seals „Natur­land“, „Bio­land“, „ASC“ and others. The­se so-cal­led sus­taina­bi­li­ty cer­ti­fi­ca­tes show the con­su­mer that the obli­ga­ti­ons of social, envi­ron­men­tal or sus­taina­bi­li­ty stan­dards have been met. For the fish feed this means strict con­trol with regard to unde­si­ra­ble sub­s­tances, raw mate­ri­als from sus­tainable ori­gin and from cer­ti­fied sup­pli­ers as well as fish meal and fish oil from safe and sta­ble stocks. In the future, the use of fish meal and oil is to be fur­ther redu­ced by using alter­na­ti­ve ingre­di­ents. Various feed manu­fac­tu­r­ers and rese­arch groups are inves­ti­ga­ting insects and various plants such as soy and rape­seed as poten­ti­al pro­te­in sources in fish feed. The use of non-gene­ti­cal­ly mani­pu­la­ted food and the use of regio­nal plants, which can con­sider­a­b­ly redu­ce trans­port distances, is of decisi­ve importance. Like­wi­se, slaugh­ter­house was­te or was­te from food pro­ces­sing is an alter­na­ti­ve pro­te­in source for far­med fish. Ano­ther pos­si­bi­li­ty is the com­ple­te switch of bree­ding to omni­vor­ous fish. The­se spe­ci­es do not requi­re a high pro­por­ti­on of ani­mal pro­te­in and the­r­e­fo­re have a smal­ler fish-in/­fi­sh-out ratio. This quo­ti­ent indi­ca­tes theo­re­ti­cal­ly how many kilo­grams of fish must be used to gain one kilo­gram of fish bio­mass. While sal­mon needs about 3 kg, tuna needs a good 20 kg (!) of ani­mal pro­te­in to achie­ve the same increase in mass.

The sea bass in our plant has a very good feed con­ver­si­on rate. The feed coef­fi­ci­ent is on avera­ge 1.3, which means that our fish only need to con­su­me 1.3 kg of feed to grow 1 kg in bio­mass. Com­pared to other fish spe­ci­es, this balan­ce can be con­side­red as very posi­ti­ve and is sup­port­ed by the use of high-qua­li­ty feed and abo­ve all by our auto­ma­ti­on. A model based on our rese­arch work in the last years is stored in the auto­ma­ti­on. The model allows the con­trol soft­ware in the SEAWATER Cube to opti­mi­ze the growth of the fish. Thus, the sea bass grow from three to about 350 grams within one year.

It remains to be seen whe­ther in the future it will be pos­si­ble to com­ple­te­ly pro­du­ce fish feed wit­hout fish meal and fish oil, becau­se ulti­m­ate­ly the­se sub­s­tances pro­vi­de one of the reasons why we eat fish: healt­hy omega‑3 fat­ty acids. Howe­ver, the latest rese­arch fin­dings and tech­no­lo­gi­cal deve­lo­p­ments sug­gest that the com­po­si­ti­on of fish feed can be made much more sus­tainable in the future.