Merck Manual

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Pet Owner Version

Special Considerations for Fish


Ruth Francis-Floyd

, DVM, DACZM, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida;

Barbara D. Petty

, DVM, North Florida Aquatic Veterinary Services

Last full review/revision Feb 2020 | Content last modified Oct 2020

A home aquarium must function as an ecosystem with specific conditions that are maintained at a constant level. Proper maintenance requires water quality monitoring, water changes, filtration, removal of waste materials, and aeration. The appropriate environmental conditions must be maintained regardless of the size of the aquatic environment, from a pond containing hundreds of gallons of water to the smallest goldfish bowl.

You will need to consider the various species of fish, which often have different behavioral characteristics, environmental and space needs, and dietary requirements. What species are aggressive or territorial? Is your tank large enough to house several species? Should the pH of the water be neutral or slightly alkaline? What temperature should the water be? Tropical fish need water kept near 77°F (25°C), while species from more temperate areas do better at lower temperatures. Will the same diet meet the nutritional needs of all species in the tank?

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