Names of fish and other aquatic animal species, including common names, follow standard rules:
blue mackerel redbait Australian sardine Thunnus maccoyii southern bluefin tuna Pacific bluefin tuna
See Animal names for further details.
The biological definition of a fish is a vertebrate animal with gills and fins (also called true fish or finfish). Many other aquatic animals also have common names ending in fish (eg shellfish). In these cases, the names are set solid:
shellfish cuttlefish jellyfish starfish
In fisheries terminology, however, other aquatic animals that are harvested for food (including molluscs and crustaceans) are also referred to as ‘fish’.
