Like most species in the carp family, goldfish produce a large amount of waste both in their faeces and through their gills, releasing harmful chemicals into the water. Active aeration by way of a water pump, filter or fountain effectively increases the surface area and helps to reduce the waste.

The goldfish is classified as a coldwater fish, and can live in unheated aquaria at a temperature comfortable for humans. Touching a goldfish can endanger its health, because it can cause the protective slime coat to be damaged or removed, exposing the fish’s skin to infection.