Stamps with the theme Fish

A fish is any gill-bearing aquatic vertebrate animal. Many fish can breathe air via a variety of mechanisms. Most fish are cold-blooded, which enables their body temperature to vary as ambient temperatures change. Commercial and subsistence fishermen hunt fish in wild fisheries or farm them in ponds or in cages in the ocean. They are also caught by recreational fishermen, kept as pets, raised by fishkeepers and exhibited in public aquaria. Fish, as a foodstuff, is an important resource worldwide.