Fish scales do not increase in number; instead, only the size of those that already exist increases.
The male emperor angelfish lives in a group with five females, and when he dies, one of the females transforms into a male and becomes the leader of the group.
The seahorse is also a fish and is the only fish that can swim vertically.
Some fish have taste sensors in their fins.
Certain species, like the triggerfish, can swim backward.