Tropical Fish Housing Guide

Aquarium size and layout

A tropical fish aquarium must be designed around the needs of the species and their adult size. RSPCA advises choosing a tank larger than 45 x 30 x 30cm, about 40 litres, and says larger aquariums generally provide more stable temperature and water conditions. This is not a universal stocking rule: the correct size depends on the fish, group size and equipment.

Filtration and heating

Filtration is essential because beneficial bacteria help process fish waste. Tropical aquariums also require a heater controlled by a thermostat, set to a temperature appropriate for the species. OATA advises keeping tanks away from draughts and heat sources and checking water quality regularly. Decorations, plants and hiding places should provide shelter while preserving suitable swimming areas.

Shelter and water quality

New tanks should be fishless cycled before stocking. Test ammonia and nitrite and do not add fish while these remain above zero. Use a water conditioner for tap water where required and avoid washing biological filter media under chlorinated tap water. Good housing is therefore a complete system: correct tank size, mature filtration, stable temperature, appropriate layout and routine testing. The aquarium should be ready before the fish arrive.