What Conditions Do Rainbowfish Need?

A freshwater fish, the Boeseman's rainbowfish (Melanotaenia boesemani) has a striking appearance when kept under ideal conditions. Mature specimens show bold shades of blue, purple, orange, red and yellow. Males usually have a more striking appearance than females. An endangered species in its natural habitat within Indonesia, aquarium enthusiasts should avoid purchasing wild caught fish.

  1. Tank Requirements

    • Male rainbowfish are slightly larger than females, and can reach up to 4 1/2 inches in length. These fish lives happiest in schools of six or more and should be kept in at least a 30-gallon aquarium. They are vigorous swimmers and require room to move freely throughout the tank. Rainbowfish need fresh water to thrive. Remove approximately 50 percent of the water in the tank each week and replace it with fresh water. Make sure the tank has a snug fitting lid to prevent the fish from jumping out.

    Light and Plants

    • Rainbowfish will live happily with other good-natured fish species. The fish seem to deliver the best coloration if kept in a mixed-sex school. Place the aquarium tank in a position where it receives one to two hours of direct sunlight per day. The sunlight will help bring out the fish coloration and make it more visible to the human eye. The rainbowfish flourishes in a planted tank. Locate plants in dense clusters also make sure the fish has open areas to easily swim around.

    Temperature and Food

    • The fish can live with a temperature of 70 to 79 degrees Fahrenheit, but the website Seriously Fish suggests maintaining the water at 81 to 86 degrees Fahrenheit. The water should have a pH of 6.5 to 8.5. Feed the rainbowfish a high-quality diet -- a mix of commercial processed fish food and live food -- to bring out the impressive coloration. The fish seem to show a particular affinity for brine shrimp, bloodworms, water fleas and tubifex worms; choose live or frozen varieties to offer the best nutrition.

    Breeding

    • The rainbowfish will readily breed in captivity. Place a male and female into a separate breeding tank. Provide ample vegetation for their eggs. Choose a sponge filler and plants that have fine leaves. Feed the breeding pair a more generous diet rich in live foods. Providing the fish with a rich diet will help recreate their natural breeding season, which occurs during the rainy season. Right before breeding with the female, the male will have a rich body coloration. Promptly remove the eggs from the tank to prevent the parents from eating them. Eggs hatch about a week after being laid. Feed the fry a liquid fry food and keep the water clean to help the youngsters grow.