All about rainbowfish for beginners (and 2 ways to build a rainbowfish tank)

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May 9, 2023
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Perth, Australia
About the rainbowfishes
Rainbowfishes are one of the fishkeeping hobby's most popular fish because of their colourful and mostly small size. They belong to the family of Melanotaeniidae in the Atherinid order. These include the Australian and New Guinea rainbowfishes, Celebes rainbowfishes and the Madagascan rainbowfishes. Most species are less than 12cm but one species of the Melanotaenia genus reaches up to a length of 20cm.
Madagascan rainbowfishes
Some rainbowfishes live in the island of Madagascar, home to the genus of Bedotia. This genus holds a lot of undescribed species of rainbowfish that have been classified by the IUCN Red List. They are not as popular in the aquarium trade as the Australian and New Guinea rainbowfishes. Their habitats are tannin-stained blackwater with riparian vegetation where the water flow is not too strong. Bedotia madagascariensis and Bedotia geayi is classified as endangered by the IUCN Red List due to habitat loss.
Australian and New Guinea rainbowfishes
The Australian and New Guinea rainbowfishes are the most common seen rainbowfish in the aquarium hobby. They are named that because of the range that the many genuses of the Melanotaeniinae subfamily live in. There are seven genera in the subfamily. Most of the rainbowfishes in the genus Melanotaenia are rare, but some species are common throughout their range. They are found in swamps and streams from Australia and Papua New Guinea. This genus is the most common aquarium rainbowfishes. The Lake Kutubu rainbowfish is an endangered example of the Melanotaenia genus. Pseudomugil is another common genus kept in aquaria. Paska's blue-eye is a critically endangered rainbowfish from this genus. It is only found in the Fly River system in Papua New Guinea.

Celebes rainbowfishes
The Celebes rainbowfishes are a beautiful rainbowfish that some hobbyists keep. There are 5 genera in this subfamily. Telmatherininae is the name of the subfamily that the silversides are in. Nearly all of them are found in the island of Sulawesi in Indonesia, with most of them living in Lakes Matano and Towuti. They are the lesser known rainbowfish because their biology remains somewhat unknown in most of this subfamily.

How to build a rainbowfish community tank
You can use your imagination for this setup. You can do moss and plants, gravel or sand, driftwood or rocks. The livestock must be compatible rainbowfish such as Boeseman's rainbowfish and dwarf rainbowfish, and other similarly compatible fish such as large tetras and catfish. Look for photos sent by other users and watch Youtube videos for reference to your setup. Let the tank cycle. Put the fish in the tank.
How to build a rainbowfish biotope tank
This is the least common setup for rainbowfish, and for more experienced hobbyists. Firstly, extensive research must be done for the biotope you choose (i.e. the Mamberamo River biotope for dwarf rainbowfish), including the pH of that biotope and the tank size of the species of rainbowfish you are looking for. Other native species might live in the rainbowfish's range, so you can add them if you want. Look into Bleher's Biotopes and have a read about rainbowfish biotopes. When you have done some extensive research into the biotope, you can start making the setup. For example, a 136 litre Mamberamo River setup contains river sand mixed in with rainforest litter. Mix the two together and pour a good amount of the mixture in. There are a few native plants in the River including: Nymphaea, Microsorum pteropus, Vallisneria nana and Aponogeton. You can place a large piece of driftwood in the middle of the tank to complete the look. Let the tank cycle and test the water parameters every month to see if everything is okay in the setup. Put the rainbowfishes in the tank.
Rainbowfish care
Many Melanotaeniid rainbowfishes come from alkaline water, so they thrive best at a pH of 7.0 to 8.0 and alkalinity between 5 and 20 dKH. Bedotiinid rainbowfishes come from more acidic water and should be kept with a pH of 6.5 to 7.5 and alkalinity between 3 and 14 dKH. Pseudomugilid rainbowfishes also come from acidic water and must be kept at a pH of 6.5 to 7.5 and alkalinity between 5 and 10 dKH. The tank size depends on the species of rainbowfish you are caring for; for the blue-eyes 10 gallons is required for a small group, some can be kept in a 20 gallon tank, and many can be kept at 30 gallons or more for larger rainbowfishes. Rainbowfishes are omnivores, they eat vegetables and frozen/live foods such as bloodworms and brine shrimp, but flakes must be the staple diet. Always feed them a small amount of food once or twice a day. 30% water changes are ideal for a rainbowfish-only aquarium. Their lifespan are between 5 to 8 years, depending on the species. Some rainbowfishes can carry a disease that is not curable called fish tuberculosis (FTB). It affects wild-caught rainbowfish. It's a major issue for the world and Australia. Buy tank bred ones to prevent FTB.

A recap of the article:
  1. There are four main subfamilies of rainbowfishes: Melanotaeniinae, Bedotiinae, Psudeomungilinae and Telmatherininae.
  2. Australian and New Guinea rainbowfishes are the most common rainbowfish in the aquarium trade.
  3. Madagascan rainbowfishes are rarer in the hobby because of specific care needs i.e. acidic water.
  4. Celebes rainbowfishes are native to Sulawesi.
  5. There are two different tank types for rainbowfish lovers to build, the biotope and the community tank.
  6. There is a disease for wild-caught rainbowfish called fish tuberculosis
  7. Care depends on the type of rainbowfish you are looking for.
Rainbowfishes are a true gem in the hobby and can be great community fish, if you care for them properly. Although there is a rare fish disease for them, the rainbowfish will mostly survive through tank-bred populations and some wild-caught fish. Other than that, these smaller rainbowfish are great for beginners and larger ones for more advanced hobbyists. Their beautiful colours are an attention-grabber for anyone who sees them. These fish are great to keep for many years to come.


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