Generally, a fish is regarded as a cold-blooded, strictly aquatic vertebrate, generally carrying fins and other adaptations for hydrodynamic travel. Over the renditions of the Creatures series, fish have taken several different forms:
- Creatures 1 had decorative angelfish, seahorse, and jellyfish.
- Creatures 2 took it a step further by introducing the edible Zander Fish and non-edible goldfish.
- Creatures 3 features an entire menagerie of edible, inedible, and sometimes dangerous fish in its Marine Terrarium, like the Rainbow Sharkling. In this game most fish can only survive in one of fresh or salt water - the Pirahna is a notable exception.
The beach-dwelling Bondi Norns are, naturally, quite partial to fish and make them a major part of their diet.