a blue and yellow rainbowfish swimming by aquatic plants


Rainbowfish are a family of freshwater fish that originate from Australia, New Guinea, Indonesia and Madagascar. More than fifty species are family members, with some being more common than others being kept as pets. Their coloring is what gives them their name; typically being iridescent shades of silver, blue and yellow. As with most fish, their coloring deepens with age and brightens with stress.

In the tank, it is advised to have no more than one male Rainbowfish, with up to five others of the group being female. This would limit aggressive male tendencies that could cause injury. This is a good community fish as it does generally get along with other species. With normal day to day activities, Rainbowfish tend to be peaceful and require low levels of maintenance. They do appreciate artificial plants and rocks that can be cleaned in their habitat for hiding. With this fish, a clean environment is very important, so consider changing the water on a regular basis to provide the best environment.

Rainbowfish Information

  • Average length: 4.5 – 6 inches
  • Attention Required: Low
  • Good tolerance to Heat and Cold: Yes
  • Good with Other Rainbowfish: Yes
  • Good with Other fish species: Yes
  • Suitable for First-Time fish Owners: Yes
  • Health Concerns: Fin rot and Ich disease
  • Average Life Span: 5 – 10 years

Physical Appearance of Rainbowfish

The fish have a long thin body and the males tend to have a hump on their backs. When the eggs of the fish hatch, the fry usually appear silverfish in color. As the pets grow older, the vibrancy and variety of the colors starts appearing. The Rainbowfish can take on any color depending on the species. The lower part of their bodies usually has a pink tinge while the rest of the body looks either silverfish, bluish, or greenish. The fins of the fish are either red to orange, or clear in color.

There are so many Rainbowfish sub-species but only a few are ideal for keeping as pets. Some of the most common species are listed here.

  • Red Rainbowfish
  • Madagascar Rainbowfish
  • Neon Rainbowfish
  • Boeseman’s Rainbowfish
  • Lake Kutubu Rainbowfish
  • Desert Rainbowfish
  • Lake Wanam Rainbowfish
a blue rainbowfish

Temperament of Rainbowfish

The Rainbowfish are peaceful and enjoy living in schools of about 6 fish of similar species. You can also have other fish species in the tank as long as they are peaceful. The pets rarely bite other fish but can be seen chasing other fish in the tank. Rainbowfish are also very active and prefer swimming from the middle or the surface of the aquarium.

It’s also worth noting that when stressed, the fish will often hide among substrates and plants in the aquarium.

a light blue and yellow rainbowfish swimming near a rock in an aquarium

Tank Conditions

Tank size

When placing a Rainbowfish in a tank, always ensure that the tank is ten times the length of your full grown fish. For example a Rainbowfish that grows to about 2 inches should be placed in a minimum of 20 gallon tank. The bigger species should then be kept in a 50 to 60 gallon fish tank. The large tanks give your fish enough swimming and hiding space.

Temperature and pH

The best water temperatures for your fish ranges between 72-82°F and having a thermometer in the tank is the best way for you to monitor for any changes in temperatures. The Rainbowfish does well in waters with pH ranging from 7.0 to 8.0.


Rainbowfish love hiding in substrate especially when they get scared. Provide medium sized gravel and smooth river rocks. It also helps if you add some hollow plastic plant materials to help your fish hide whenever they want to.

The Attention Requirements of Rainbowfish

Rainbow fish are low maintenance and are a favorite for beginners. The fish rarely gets sick as long as water quality is maintained. The fish also don’t need to eat every day. You can be away from home for a long weekend without needing anyone to feed your fish.  

The fish are accustomed to going without food for days during famine periods in the wild. A Rainbowfish is the best choice for anyone looking for a pet despite their busy schedules.

Tank Maintenance

You should check the temperature on a daily basis to ensure that it remains constant. You should also look at the filtration of your tank to confirm that it’s functioning correctly daily. Water testing kits are also a must have for any aquarist. You need to test the quality of your fish water once a week. Ammonia, nitrites, and nitrate levels should always be at zero percent.

Water changes also contribute towards giving your Rainbowfish a healthy environment. Conducting 10 – 25 percent water changes every 2 to 4 weeks is recommended for Rainbowfish tanks.

a silver and yellow rainbowfish swimming near aquatic plants
a silverish blue and yellow rainbowfish swimming in an aquarium

Best Tank Mates for Rainbowfish

Rainbowfish are calm and non-aggressive species. They like to shoal and should be kept in groups of six or more. Rainbowfish are easygoing and will let other species live peacefully in the tanks. Here is a list of best tank mates for the Rainbowfish.

Rainbowfish do not attack larger species even when they feel threatened. They will just hide behind plants and rocks when they feel threatened. They will enjoy the company of active and peaceful species in the tank. Larger size and aggressive species should not be kept with the Rainbowfish.

Health Issues

Rainbowfish are generally very immune to many types of sickness and rarely succumb to illnesses. In this section, we’ll discuss some of the most common diseases that affect the fish.

But first, we need to cover some preventative measures you can take to prevent sickness in your fish tank.

The first step towards having happy and healthy pets is ensuring that you try to give them living conditions close to their natural habitat in the wild. For example, mimicking the temperatures, water hardness, and pH that the fish survives best while in the wild.

The quality of the food is also a great determinant on how healthy your fish remains. Offer your fish a well balanced diet and in the right portions.

Stress can also weaken the immune system of your fish. Rainbowfish especially get stressed if they don’t have enough space to swim. The fish also love to hide and burrow in substrates and other aquarium decorations. Lack of such hiding materials in the tank can easily stress your pet.

You should also constantly monitor the level of organic waste in the water. An increase in the amount of ammonia, nitrates, and nitrites contaminates the water and which then weakens the immunity of your pets. Fish with a weak immune system are susceptible to many fish illnesses.

Another important aspect that could help you control and prevent diseases in your fish tank is keeping new tank mates under quarantine. You should never bring a new fish into the tank without first watching it for any signs of illness. A sick fish introduced to an aquarium can easily spread the disease costing you all your pets.

Here are some of the most common diseases among Rainbowfish.

a silver and red rainbowfish with reflections of blue on the scales

White Spot Disease

Ich is one of the most common diseases found in Freshwater fish. The disease is caused by a parasite that affects the gills and fins of the body. Poor water conditions and stress are major reasons that can lead to the fish catching this disease. When a fish becomes infected with Ich, it tends to rub against hard objects such as decorations, rocks and the substrate.

Symptoms include white spots on the body, breathing difficulty and fish rubbing against hard surfaces. In comparison to other fish diseases, these symptoms make it easy to identify if your fish is infected. 

A major concern is that this disease is highly contagious and can easily spread to other fish in your aquarium. If not treated early on, it can even cause respiratory issues. 

Treatments include slightly increasing the water temperature, adding medication to the tank and performing a large water change. If you have a community fish tank then it is suggested to move the infected fish into a quarantine tank and then treat them.

Fin and Tail Rot

Fin and tail rot is a common freshwater disease that is named after what happens to the fish that have it. Fish infected with fin and tail rot will have fins or tails that appear frayed, or parts of them missing. The disease may also cause white milky areas on the body, especially on the tail or fins.

Symptoms of Fin and Tail Rot

  • Fins or tail appear to have frayed or abnormal edges
  • The fin or tail edges have turned white
  • A part of the fin or tail is missing

Like Ich disease, fin rot is also a result of poor water conditions and high stress levels. Fin and tail rot can be caused by fungi or bacterial infection. Identifying the cause of the disease, bacteria or fungi, is important to treat them because both are treated differently. Infected fish should be quarantined and treated in a separate tank. 

The easiest way to prevent your fish from catching this is to keep their water as clean and healthy as possible. After that the next biggest causes are stress, or attack from other fish. Try not to keep fish that can attack other fish, and give your smaller fish plenty of places to hide with plants or decorations.

Antibiotics will be needed to treat any fish that have this disease.

fish food

Feeding Rainbowfish

Rainbowfish are omnivorous and can eat both meat and vegetable foods. Commercial pellets or flakes make a good choice of food for pet Rainbowfish because they contain most of the essential nutrients. You should also supplement the diet with very finely shredded vegetables such as peas, carrots, and spinach. 

Since in the wild Rainbowfish eat a lot of small insects and crustaceans, you should give them live food such as bloodworms, daphnia, and larvae. Dry and frozen foods are also readily available in the pet stores but make sure to cut them into small pieces before feeding your fish. 

Remember Rainbow fish are generally very small fish and feeding them large chunks of food could lead to choking.

It’s also important to note that Rainbowfish are middle to surface dwellers and therefore prefer feeding from the surface of the tank. You can buy some fish feeding clips. These will allow you to suspend the fish food at the surface. 

Any food that drops to the bottom of the aquarium is often waste and could easily contaminate the quality of your water if not cleaned well.  Some aquarists place Rainbowfish with other fish species that feed from the bottom such as the catfish. The trick helps to make sure that no food gets wasted.

Overfeeding is a common problem among Rainbow fish. In the wild, the fish are used to fattening up during the seasons with plenty of food. The season that follows is often accompanied by drought and the fish make use of the stored fats to survive.

In the situation where Rainbowfish are kept as pets, they may tend to overfeed when they see a lot of food. The problem that then happens is that the fish may not experience shortage of food in an aquarium. Eventually, you may end up with obese fish or they may develop digestive problems.

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