A recirculating aquaculture system (RAS) grows fish in a closed loop: the same water is continuously pumped through a biofilter, aerated and returned to the tank instead of being discharged. That makes water quality — not space — the thing that actually limits how many fish you can grow. This rig lets you tune the four decisions a RAS operator makes every day and watch dissolved oxygen, ammonia and fish growth respond live.
Oxygen saturation falls with temperature: DO_sat(T) ≈ 14.6·e^(−0.027·T) mg/L.
Fish respiration scales with biomass and temperature (Q10 rule):
O₂ demand = biomass · MO2_ref · Q10^((T−15)/10).
The tank is modelled as a stirred reactor: dDO/dt = flow·(DO_sat − DO) − O₂ demand / volume.
Ammonia builds up from uneaten feed and excretion and is stripped by the biofilter in proportion to flow:
dTAN/dt = feed·k_N / volume − flow·k_bio·TAN, with the toxic un-ionized fraction
NH₃ = TAN / (1 + 10^(pKa−pH)) rising sharply as water warms.
Because RAS tanks reuse over 90% of their water, well-run systems use a small fraction of the water a traditional pond farm needs for the same harvest — but that efficiency only holds if the biofilter keeps up with the fish, which is exactly the balance this simulation lets you break.
A 3D closed-loop fish farm where you control stocking density, feed rate, water exchange rate and temperature, and watch dissolved oxygen, ammonia and fish growth respond live as the water is pumped through a biofilter and back into the tank.
In a recirculating aquaculture system, water quality — not tank space — is what actually limits production: fish oxygen demand and ammonia excretion both scale with stocking density and feed rate, while the exchange rate through the biofilter and aerator is the only thing keeping dissolved oxygen up and ammonia down.
Raise stocking density and feed rate to grow more fish faster, then watch dissolved oxygen fall and ammonia climb. Increase the water exchange rate to recover, or lower the temperature to cut fish metabolism and boost oxygen saturation. The status badge and probe LED flag hypoxia and ammonia toxicity as they happen.
Because RAS tanks reuse over 90% of their water instead of discharging it, a well-run system can produce the same harvest as a traditional pond farm on a small fraction of the water — but only as long as the biofilter keeps pace with what the fish put into the water.