Fish farming tank

The cen­tral com­po­nent of an aquacul­tu­re faci­li­ty is the bea­ring tank. Its dimen­si­ons and capa­ci­ty influence both which fish spe­ci­es can be held (body size, swim­ming beha­vi­or) and the annu­al pro­duc­tion volu­me (water volu­me, num­ber of cohorts, sto­cking den­si­ty). But what are the dif­fe­rent types of fish tanks and which spe­ci­es are kept in our faci­li­ty? In the fol­lo­wing we give a short overview.

Com­mon in aquacul­tu­re are many sin­gle, most­ly round tanks. On the one hand, the­se are available at very low cost and on the other hand, the cohort model can be easi­ly imple­men­ted. Only fish of a cer­tain size and age are assi­gned to each tank (=cohort). If the fish of a cohort are too lar­ge for one tank due to growth, they are trans­fer­red to the next lar­ger tank. The indi­vi­du­al round tanks are each con­nec­ted with pipes and are also con­nec­ted to the fil­ter tech­no­lo­gy by pipes. The­re are seve­ral pumps that trans­port the water through the sys­tem. Howe­ver, this high piping and pum­ping effort is a dis­ad­van­ta­ge of the sin­gle tank vari­ant. On the one hand, the long pipe­lines favor a loss of pres­su­re and thus ener­gy. On the other hand, this leads to hig­her cos­ts. Ano­ther dis­ad­van­ta­ge of the round tank vari­ant is that the ani­mals are moved eit­her mecha­ni­cal­ly or with a landing net when they are moved to ano­ther tank. This hand­ling cau­ses stress and often dama­ges the fins and the pro­tec­ti­ve slime lay­er on the skin of the ani­mals. This makes the fish sus­cep­ti­ble to pathogens.

In the SEAWATER Cube, we deci­ded on a sin­gle lar­ge basin with a spe­cial geo­me­try. This allows us to redu­ce the piping to a mini­mum and also redu­ces the requi­red pump ener­gy and saves cos­ts. In addi­ti­on, the shape of the basin opti­mi­zes the flow towards the fil­ters, thus faci­li­ta­ting water purification.

The hol­ding area is divi­ded into three sec­tions, each of which is sepa­ra­ted by spe­cial nets. Each tank sec­tion hou­ses fish of a dif­fe­rent life stage: fries (up to 50g), juve­ni­les (up to 150g) and mar­ket-rea­dy ani­mals (up to 400g). The size of the indi­vi­du­al tank sec­tions is sel­ec­ted so that a sto­cking den­si­ty of appro­xi­m­ate­ly 65 kilo­grams of fish per cubic meter of water volu­me is never excee­ded. The­re are lite­ra­tu­re refe­ren­ces that sta­te that for sea bass, stress in the ani­mals is only detec­ted from 100 kilo­grams of fish per cubic meter upwards. We are well below this level, as we want to rai­se the ani­mals as gent­ly as possible.

In each tank sec­tion the fish live for 4 months. The trans­fer is cont­act­less and almost stress-free through sluices in the net con­s­truc­tion. Con­se­quen­ti­al dama­ges of the fish due to an impair­ment of fins or slime lay­er are excluded. When the fish are ful­ly grown after 12 months at the latest, they are fished out manu­al­ly with the landing net ins­tead of with machi­nes. This pro­tects the fish and keeps the stress as low as pos­si­ble, which ulti­m­ate­ly can be tas­ted in the fle­sh of the fish.