El-Fish is a fish and fish-tank simulator developed by Russian game developer AnimaTek, with Maxis providing development advice. The game was published by Mindscape (v1.1) and later by Maxis (v1.1 + v1.2) in 1993 on 5 diskettes.
Each fish in El-Fish has a unique Roe, similar to the genome. This allows the user to catch fish and use selective breeding and mutation to create fish to their own tastes for placing them in virtual aquariums. Around 800 possible genetic attributes (fin shape, body color, size, etc) are available, which can be selectively shaped into virtually infinite numbers of unique fish. Once fish are created, El-Fish will algorithmically generate up to 256 animation frames so that the fish will appear to swim smoothly around the tank.