Rainbowfish are made up of two main groups. The first group contains the Families Melanotaeniidae and Bedotiidae, which include larger, active fish in the genera Melanotaenia, Glossolepis and Bedotia, like the Madagascar Rainbow. (An exception is the tiny Threadfin Rainbow, I. werneri, which should be treated like a Pseudomugilid.) The second group includes the Families Pseudomugilidae and Telmatherinidae. Pseudomugilidae is comprised of smaller, more docile fish, often referred to as “Blue Eyes”. The Family Telmatherinidae includes a lone species, Marosatherina ladegesi, the Celebese Rainbow. It is not hard to understand how rainbowfish get their name once you see a school of brilliantly colored, adult Melanotaeniids or a pair of “Blue Eyes” in full spawning dress.
A Rainbowfish's Natural Habitat
Rainbowfish are native to Australia, Papua New Guinea and parts of Indonesia, where they are found in streams, rivers, lakes and swamps. Some wild rainbowfish populations have become threatened by human activity, as well as the introduction of invasive species. Most rainbowfish available in the hobby are produced commercially on farms in Southeast Asia and Florida.
Rainbowfish Water Requirements
Many Melanotaeniids come from hard, alkaline water, but captive bred fish available today will thrive in a wide range of water conditions. They do best between 74° and 78° F, at a pH of 7.0 to 8.0 and alkalinity between 5° and 20° dKH (90 ppm to 360 ppm). Madagascar Rainbows come from more acidic water and should be kept between 74° and 80°F, pH of 6.5 to 7.5 and alkalinity between 3° and 14°dKH (55 ppm to 250 ppm). Pseudomugilids prefer temperatures between 76° and 82° F, pH of 6.5 to 7.5 and alkalinity between 5° and 10° dKH (90 ppm to 180 ppm). If the aquarium is kept in a room below 74° F, use an Aqueon Aquarium Heater to maintain the correct temperature. Maintain good filtration and do a 10% water exchange every week or 25% every 2 weeks using an Aqueon Aquarium Water Changer or Siphon Vacuum Gravel Cleaner. Don’t forget to treat tap water with Aqueon Water Conditioner before refilling your aquarium!
Housing Requirements for Rainbowfish
Melanotaeniids are active fish and need plenty of swimming space. Smaller species like the Neon Dwarf Rainbow (Melanotaenia. praecox) and the Celebese Rainbow (M. ladegesi), will thrive in a 30-gallon aquarium, whereas most other Melanotaeniid rainbowfish need an aquarium of at least 50 gallons or larger. Adequate cover in the form of tall plants and other structures is important, but open swimming areas should be provided as well. The “Blue Eyes” and Threadfin Rainbows are perfectly happy in community aquariums of 20 gallons or well-planted species tanks of 10 gallons or less.
Melanotaeniid rainbowfish are peaceful yet active and get along with most similarly sized, non-aggressive fish. Different species can be mixed together and can also be kept with larger tetras, peaceful barbs, rasboras, danios, catfish and even non-aggressive cichlids such as Kribensis. Rainbowfish are shoalers and should be kept in groups of 6 or more for best effect. Males will exhibit their best colors as they vie for attention from females. Pseudomugilids and Threadfin Rainbows are docile and sometimes shy, so tank mates should be chosen carefully. These may include pygmy rasboras, small tetras, peaceful barbs, Otocinclus and Corydoras catfish. Always consult an aquarium expert before buying any new fish for your aquarium.
What Do Rainbowfish Eat?
Rainbowfish are omnivores and need both vegetable matter and meat-based foods in their diet. Melanotaeniids will thrive on Aqueon Tropical Flakes, Color Flakes, Spirulina Flakes and Betta Treat. Pseudomugilids will accept these foods as well, but may require a higher proportion of frozen and even live foods to promote optimum health and color. For best results, rotate your fishes’ diet daily and feed only what they can consume in under 2 minutes, once or twice a day.
Rainbowfish Breeding Level - Intermediate
Rainbowfish are egg scatterers and provide no parental care once the eggs are laid. Many Rainbowfish spawn in vegetation or can be induced to deposit their eggs in yarn mops. A slight increase in temperature will often induce spawning activity. Eggs hatch in 7 to 21 days depending on temperature and species.