Other books Water Chemistry by Mike McEwan Temperature Water temperature affects the amount of dissolved oxygen water can hold. Cool water holds more oxygen than warm water. Obviously, though, we can't just lower our aquarium's water temperature to increase its oxygen content.
Tropical fishes require warm water.
While many of them may tolerate a fairly wide range of temperatures, they thrive and reproduce in a narrower range. A little research on your part can add to your pets' health. Good aquarium publications, such as FAMA , usually give optimum temperatures for the critters they cover. Winter may create no special problems if you keep only species native to your region. Even inside your home, though, tropicals will need some added warmth.