Betta fish aquariums

From Betta Fish Wiki

To maximize the well-being and lifespan of the fish, they must be kept in appropriately-sized tanks. For each 1.0 cubic inch (16.4 cm³) of fish there must be, at least, 1.0 gallon (3.780L) of water.[citation needed] To keep a single fish, a minimum-capacity tank of 10 litres (3.0 U.S. gallons) is recommended; some authorities recommend a 20-litre (5.0 U.S. gallons) capacity tank. [2] This minimum ratio (eight litres per fish) is true for females and males individually kept, and for cohabiting females; thus, the smallest female community tank is 30 litres (10.0 U.S. gallons), e.g. four females.

A tank of 20 litres (5.0 U.S. gallons) allows use of a heater to maintain a 28°C (82°F) temperature. Temperatures lower that 25°C (76°F) render the fish lethargic and illness-prone. Drastic temperature changes can shock the fish, and be fatal. The optimal pH level is between 6.5 and 8.0, which must be monitored to ensure the fish's health, especially if carbon dioxide (CO2) injection is being used in a tank containing plants. Since the betta splendens fish also obtains oxygen from the air, the tank must not be covered with an air-tight lid, so the fish may easily reach the surface, and not have a gap large enough for it to jump out.

Betta splendens fish often are kept in small containers for display; many drown because they are too small to allow the fish to surface for air. Small containers are mainly for transport from the shop to the tank. When kept in a small container, the fish need frequent, sometimes daily water changes to flush from it the fatal ammonia accumulation that is the fish's principal cause of death.