How To Care For Rainbowfish-A Simple Guide

The beautiful rainbowfish was made famous because of a children’s book. There are more than 50 species of rainbowfish that can be found all over the world. Those 50 species fit into 4 categories and they have become very popular fish to keep in your home aquarium. Rainbowfish are peaceful, easy to care for, are no bigger than 5 inches when adults, and come in a variety of colors.

How do you care for rainbowfish? You need to keep your aquarium between 74 and 78 degrees. This mimics their natural habitat temperature. They are omnivores, but they still need green vegetables and high-protein foods. They also need plenty of swimming space, very clean water, and a stress-free environment.

As long as you maintain those simple aspects, your rainbowfish will remain healthy and happy. 

The lifespan of a rainbow fish is about 5 years in duration. Rainbowfish love to have a peaceful habitat, tall plants, and being able to swim in schools of 6 or more. The perfect rainbow fish habitat is crystal clear water, 6+ other rainbow fish, and hiding places.

Rainbowfish are extremely tolerant of varied water environments and can adapt well to semi-aggressive tank mates. 

I am going to examine and share many more aspects of taking care of your rainbow fish; behavior, eating habits, tank conditions, tank mates, diet, and more. I hope, by the end, you will be very confident about raising rainbowfish in your freshwater aquarium. There is quite a bit of information to cover, so let us get started. 

Rainbowfish Behavior

Rainbowfish are shy. They prefer to travel with 6 or more rainbow fish, as mentioned above and they are not aggressive at all. They would prefer to hide if they feel threatened or scared.

The rainbowfish enjoy a tranquil environment so avoiding stress is a big must. Make sure that your tank has a few good hiding spots for your rainbowfish. Even if they do not feel threatened, they like to ‘hide’ when it is time to rest and recharge.

If you have more than 1 male in your tank you may have a little aggression during mating season. This is best solved by having more females in the tank, than males. Then there shouldn’t be as much competition. Rainbowfish also have a habit of jumping if they are threatened or scared so please make sure that you have a tight-fitted lid on your tank.

Rainbowfish Looks (Appearance)

The rainbowfish are beautiful creatures because of their stunning colors. The males will get brighter in color when they are in groups and especially during mating season.

You definitely won’t get tired of looking at the myriad of colors in your aquarium. The older the rainbowfish is the brighter the colors as well. Rainbowfish change colors depending on their mood, time of day, and to attract females. 

Tank Conditions For Rainbowfish

The rainbowfish prefer fairly alkaline hard water. This mimics their natural environment whether it is a lake, river, or stream. They also love a lot of tall live plants to snack on and to hide behind. But, don’t over-do the plants because they also like to have a wide-open space to swim around. 

Depending on which species of rainbowfish you have, the temperature will vary a little bit. The most common species, Melanotaeniids, prefer a temperature range of 74 to 78 degrees.

Their pH level should be between 7.0 and 8.0. The other species of rainbowfish like temperatures ranging from 74 degrees to 82 degrees and a pH balance of 6.5 to 8.0.

Rainbowfish Aquarium Size

Depending on the species of rainbowfish you can use a 10 gallon, 20 gallons, or even a 50-gallon aquarium. The number of fish you want to keep is also going to determine what size of tank you need. Rainbowfish are active and enjoy swimming from one end of the tank to the other. 

Plan on having approximately 2.5 liters of water per rainbowfish. 2.8 liters for the medium-sized species and 5.7 liters for the larger rainbowfish. So in a 20-gallon tank, you have 75.7 liters of water. This will house 15 medium-sized rainbowfish comfortably.

I would only put 10 rainbowfish in the tank, just to ensure that they had plenty of room to swim around with the live plants and other decorations in the tank.

Rainbowfish Diet 

As stated at the beginning of this piece, rainbowfish are omnivores. In their natural habitat they will eat mosquito larvae, so having live food will be extremely beneficial. 

Some foods that you can cycle in and out of their diet include:

  • Pellets
  • Spirulina flakes
  • Ground vegetables
  • Blackworms
  • Glass worms

There are other foods as well, that are nutritious for your rainbowfish and can be included in their diet. Just do a little extra research to obtain the complete list. 

It is recommended that you do not feed them the same things every day. Give them something different each day to provide different nutritional sources. This helps to recreate their feeding habits in nature. 

**Tip** rainbowfish are surface feeders so they will not eat anything that falls to the bottom of the tank. So only feed them what they can eat in 2 minutes, this prevents extra waste in the aquarium.

Caring For Rainbow Fish

These fish are extremely easy to care for. As long as their water is crystal clear, there are other rainbowfish in the tank, and they have no stress then you will have no worries.

You do, of course, still have to watch out for disease and things in your aquarium. But this is less likely to happen when the aquarium is kept as clean as possible.


As mentioned in our other articles, decorations can be a great source for good bacteria to grow on. Rainbowfish enjoy having hiding places in their environment in case they feel threatened, scared, or they just want to rest without being disturbed.

You want to provide a variety of colors and sizes when it comes to your live plants. A couple of prime ones to use; Java Fern and the Java Mass. When choosing your decorations remember to not over-do them.

Some Tank Mates For Rainbowfish

Rainbowfish are shy and are non-confrontational fish when they are threatened. When choosing tank mates for your rainbowfish keep in mind that they like to swim in schools of 6 or more.

It would also be beneficial to add tank mates that are peaceful, calm, and have a very similar diet. This will help keep the stress down tremendously, which is a huge benefit.

The most popular tank mates are:

  • Kribensis (species of cichlid)
  • Danios
  • Barbs
  • Rasboras
  • Nescoridina
  • Catfish
  • Large tetras
  • Caridina shrimp

Other Rainbowfish Interesting Facts

When rainbowfish are young they are often bland in color. So when people go to the pet store to purchase fish, they often overlook the young rainbowfish and opt for the more colorful ones.

Unless you do your research ahead of time you would not know just how beautiful and spectacular rainbowfish color can become as they get older. 

Because they are so simple to take care of, the rainbowfish would make the perfect starter fish for teaching children responsibility. They would enjoy the fascinating colors and starting them with a peaceful, easy to care for fish is optimal. 

It is recommended that you do a 25% water change every other week. Again, to make the water changes easier and to keep them at every other week, do not feed the rainbowfish anymore than they can eat in 2 minutes.

The rest will sink to the bottom causing more waste which causes more bad bacteria, ammonia, and other harmful debris in your aquarium. Too much of these harmful things from too much feeding and you will have to do your water changes once a week.

Final Thoughts

Exotic and majestic rainbowfish are an especially colorful way to ‘decorate’ a room in your house. Adding a 20-gallon aquarium with 10-15 rainbow fish would draw your guests to it the minute they saw it. Rainbowfish change colors for many reasons so they are beautiful to just sit and watch. They are also extremely easy to care for. 

A high-quality filtration system, good heater, lighting, substrate, thermometer, plenty of swimming space, and tranquil environment is all a rainbowfish needs. Throw in an easy, well-balanced diet and you have the most wonderful, adaptable, and gorgeous pet.

They are not aggressive, they do not like confrontation, and they are laid-back. All a rainbow fish wants to do is munch on plants, rest in a hiding spot, and swim until they can not swim anymore. 

Remember, when you go to the pet store to buy fish for your next aquarium or for the first time, do not overlook the young rainbowfish. Snatch up those bland looking little guys or gals and take them home. Watch these plain fish evolve into the most bright array of color combinations that one can only imagine. You will not be disappointed.


I'm passionate about fish pets and love sharing everything I learn about them.

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