Goldfish. There are more than 100 kinds of goldfish. Goldfish are omnivorous, which means these common household pets eat both plants and animals.

Betta Fish. These gorgeous freshwater fish are also called Japanese or Siamese fighting fish because the males of this species will fight to the death if placed together in a tank. Bettas can be found in many colors, including red, blue, green and even white.

Molly. Most are black, green, silver or gold. This popular type of fish can have short or long fins. They need some plant matter in their tank to remain healthy and happy.

Tetra. These are tiny fish from South America that make a pleasant addition to many fish tanks, as they live peacefully with other fish. Bigger fish will sometimes eat them, though. One popular variety of tetra has a bright, neon tail.

Catfish. These are bottom-feeders. They will park themselves at the bottom of a tank and gobble up the food that the other fish missed. Many types of catfish are nocturnal and like to hide in the sand, plants, toys or rock caves available to them.