It depends on the type of fish you have!
Discus, wild caught angelfish, uaru and certain other fish that are found at or near the equator do better at temperatures between 84° and 88° F.
Betta fish thrive best in water temperatures between 76° and 85° F.
Most tropical fish prefer temperatures ranging from 76° to 80° F.
Goldfish, koi and other coldwater fish prefer the temperatures be between 65° and 72° F.
Research the particular fish before determining what temperature to keep the aquarium! Visit our care sheets to learn more about specific types of fish.