From Envirowiki

A Fish is an animal that lives in water it whole lifecycle. Fish breath water. Fish are often found in any permanent water that is not stagnant, including fresh water and salt water.

The world's fish stocks are currently threatened by over fishing. Some species, such as tuna, and some shark species are threatened with extinction. This is leading to fishing down the food web, resulting in the rise of slime.

Fish are a common human food source (too common), and are high in dietary minerals, protein, and omega fatty acids.