How to Care for Rainbowfish?

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It’s not hard to understand why so many aquarists love the Rainbowfish. This is a peaceful, colorful, and adaptable species, capable of being assimilated into any aquatic setup within certain limits.

That being said, you require extensive knowledge to learn how to handle the fish long-term and improve its quality of life.

What do you need in terms of tank layout, water conditions, diet, and tank mates? We will discuss all these aspects and more in the following sections.

Rainbowfish Species and Types

There are around 50 species of Rainbowfish that we know of today, and all of them differ slightly in areas like coloring, size, pattern, lifespan, and even temperament. Knowing which one is the best for you comes down to personal preference and tank setup.

The interesting aspect is that Rainbowfish has multiple tank-compatible species, most of which are perfect for beginners.

Some of the most popular Rainbowfish options to consider are:

  • Boseman Rainbowfish – This species is slightly bulkier with a small head and a pointy snout. The fish is almost always light yellow or even white around the head and gradually gains orange hues towards the tail. It’s a clean-looking and more colorful Rainbowfish that will grow around 4 inches and is suitable for community setups.
  • Dwarf Rainbowfish – As the name suggests, this is the smallest Rainbowfish species you can get, but it’s also the most colorful and fanciful, in my opinion. The Dwarf Rainbowfish displays a metallic blue body with bloody-red fins and tail. The females are more silvery, as they display less blue than the males. The Dwarf Rainbowfish will only grow up to 2 inches which is up to 3 times smaller than the largest Rainbowfish.
  • Lake Kuku Rainbowfish – This is another highly popular species and one of my favorites as well. The Kuku Rainbowfish can grow up to 5 inches, probably more with optimal care, and will display varying colors. Some have full blue bodies with only minor variations in the color’s intensity. Others have a slightly different pattern, displaying white bellies and a blue-green body coloring. Either way, you can’t go wrong with Kuku.
  • Madagascar Rainbowfish – This specimen also packs a unique look that’s vastly different from what you would expect from a Rainbowfish. The Madagascar Rainbowfish can reach up to 6 inches in size and displays a slender and thin body. Its body conformation is slightly unusual since most Rainbowfish species have wider bodies. This is great since few things are as exhilarating as a school of blue Madagascars darting through the tank’s vegetation.
  • Murry River Rainbowfish – This species will likely grow up to 3-4 inches and come with an intriguing color pattern. Most Rainbowfish falling into this category showcase a metallic-looking body with white, brown, and gold nuances. It’s pretty much like a jewel floating through the tank, reflecting sunlight and sparkling in the water.

There are many other tank-viable Rainbowfish species to consider, depending on your available space and personal preferences.

Ultimately, whichever species you choose will have little impact on its care requirements or water parameter demands.

All Rainbowfish will thrive in the same conditions and will accept the same type of tank mates.

Rainbowfish Requirements

Fortunately, this is a hardy and adaptable aquarium fish species that will thrive in a well-maintained setup.

The main parameters to consider for your fish include:

Tank Size

Nothing beats the importance of the tank size when it comes to accommodating your Rainbowfish.

Although they are not too demanding in this department, they do require their personal space to remain healthy, comfortable, and happy. When it comes to the tank size, you need to consider the fish’s social behavior.

Rainbowfish are schooling fish, so they have a pretty well-developed social behavior. This means you shouldn’t keep your Rainbowfish alone since they will become stressed with time.

So, when calculating the fish’s necessary space, you need to consider the size of its school.

An optimal Rainbowfish school layout should comprise at least 6 individuals, but more is always better. Depending on the species and the school’s size, Rainbowfish may require between 30 and 50 gallons of space.

This is the minimum necessary, which means you can go bigger than that. Your Rainbowfish will always use the extra space wisely, so nothing will be wasted.

Not to mention, investing in a larger tank is always smart in my book. You never know when you decide to add more fish to the bunch or create a community setup since you already have the extra space.

The latter is almost bound to happen at some point, given the Rainbowfish’s peaceful and friendly demeanor.

To close this point, I would like to advise against taking the fish’s adaptability for granted. Many aquarists ignore the importance of space when it comes to Rainbowfish, precisely because this species is so peaceful and adaptable.

The problem is that if the fish doesn’t have sufficient space, it will suffer even if it doesn’t look like it.

When overcrowded or forced to live in an unusually small environment, Rainbowfish will display signs of stress, irritability, and even violence, however atypical.

With time, the fish will even fall sick more often due to a weaker immune system. So, never take its adaptability for granted.

Water Parameters

Rainbowfish display slightly different environmental requirements, depending on the species. The fish prefers harder and more alkaline waters in the wild but has learned to adapt to a variety of water conditions in captivity.

Most species will do just fine at temperatures around 72 to 84 °F and a pH value between 7.0 and 8.0.

Other species, like the Madagascar Rainbowfish, will prefer lower temperatures, up to 80 °F, and pH between 6.5 and 7.5.

The point is that there are slight variations between water parameter preferences among different Rainbowfish species.

Always consider your particular species’ water requirements to learn how to accommodate the fish in their new habitat.

But if there’s one thing that all Rainbowfish agree on, it has to be their aversion towards ammonia and nitrites. Obviously, this is a typical response since ammonia and nitrites function as poison for fish.

Fortunately, it’s pretty easy to combat this issue, so long as you provide your Rainbowfish with regular water changes and tank maintenance.


Rainbowfish are mid-to-top dwellers, so they will rarely go near the substrate. That’s because they typically hunt insects floating on the water’s surface, so they have adapted to that lifestyle.

They will follow a similar approach in captivity, spending most of their time in the tank’s mid area and going towards the water surface to feed. So, choosing the right substrate is pretty much a matter of personal preference.

I would say that sand is the better alternative if you want an easy-to-clean substrate that also packs a great esthetic look.

Gravel is also a good option, especially since it can come in a variety of colors and sizes. The problem is that it’s more difficult to clean since fish waste and food particles will sink in through the rocks.

If you aim for the best of both worlds, I would recommend river rocks or a live rock system. Either option is easy to clean and maintain and will beautify your aquatic setup.

Whichever substrate you choose, remember that Rainbowfish require some hiding spots, despite being a mid-dweller.

Consider some caves, arches, driftwood, and plants to provide your Rainbowfish with a natural-looking setup where they would feel comfortable and at peace.


This is an interesting topic thanks to the Rainbowfish’s behavioral diversity. We should begin this segment by stating that Rainbowfish are omnivorous creatures.

They will consume animal and plant-based protein to ensure an optimal intake of nutrients.

The problem is that some will get their plant-based nutrients from their environment, eating the live plants and decorating their habitat.

Those Rainbowfish will consume tank plants no matter how many veggies you feed them. And if your Rainbowfish loves plants, there’s nothing you can do about it other than provide it with a constant flow of live plants to satisfy its appetite.

Some of the plants that Rainbowfish will prioritize include stargrass, duckweed, glosso, tonina fluviatillis, and others.

Then you have the Rainbowfish that don’t eat plants. They simply don’t like them and, just as is the case with the plant-eaters, there’s nothing you can do about it.

These fish will get their plant-sourced nutrients from other sources, mainly veggies, flakes, and pellets.

Unfortunately, you can’t tell which Rainbowfish will eat plants and which won’t. These fish have different personalities, temperaments, and preferences.

You might have specimens belonging to the same species that display different dietary preferences. Be mindful of your Rainbowfish’s feeding behavior and adapt accordingly.

Assess their relationship to the plants decorating their environment and go from there.


The tank equipment is pretty standard. Ensure a stable environment for your Rainbowfish with steady temperatures and healthy water parameters.

This requires you to invest in a heater and a filter, especially if the tank is smaller in the neighborhood of 30 gallons.

Generally speaking, the smaller the tank, the faster the water will get dirtier, showcasing accelerated ammonia buildup.

To prevent that, you need a reliable filtering system, combined with regular tank maintenance and water changes. Fortunately, Rainbowfish aren’t exactly too messy, so cleaning after them should be fairly easy.

You may need to adjust the maintenance schedule based on your tank’s size and how many fish you have. A larger tank may not need cleaning as frequently as a smaller one.

Rainbowfish Feeding and Diet

Rainbowfish are omnivorous, so they will eat a variety of foods. One thing to know about them is that they’re surface eaters.

These fish prey upon unsuspecting insects sitting on the water’s surface, which means they will get accustomed to floating flakes pretty easily.

Setting up their feeding schedule isn’t too difficult either. Rainbowfish should have up to 2 meals per day and have enough food for them to consume within 2 minutes at most.

You should also rotate their meals every day so that they won’t get the same foods.

This helps them experience an optimal nutrient intake from multiple food sources like live food, flakes, spirulina tablets, veggies, etc.

Many Rainbowfish will also eat some of their live plants on occasion.

Rainbowfish Tank Mates

Fortunately, Rainbowfish are very peaceful and docile creatures, capable of adapting to pretty much any social setup. However, you can’t house them with just any fish.

You should be mindful of several aspects when looking for their ideal tank mates:

  • Avoid aggressive and territorial species – Rainbowfish are peaceful, so it’s unlikely that they will display any aggressive or territorial behavior. Pairing them with aggressive fish species will inevitably lead to the Rainbowfish experiencing bullying and even risking injuries and stress-related diseases. Always pair your Rainbowfish with equally peaceful fish species.
  • Look for fast swimmers – Rainbowfish are fast and energetic swimmers that like to dart around their environment, typically in a school or shoal. Their tank mates should display a similar temperament or, at the very least, not mind the Rainbowfish’s extra adrenaline. Otherwise, the fish will become intimidated and stressed by the Rainbowfish’s high energy, and you don’t want that.
  • Avoid fin nippers – Some fish love nipping at their tank mates’ fins. This places the Threadfin Rainbowfish in danger when housed with otherwise peaceful and playful fish-like barbs. These small creatures showcase a vivid predilection for nipping at the Rainbowfish’s fins and poking at it constantly. As a result, your Rainbowfish may become stressed, especially if it has nowhere to hide.
  • Mind the male-to-female ratio – While Rainbowfish are calm and collected, they will display competitive behavior over food and females. Males will often fight with each other if there aren’t enough females for all of them. You should have at least 2-3 females for one male to mitigate their competitiveness and mating-related aggression.
  • Always consider a school of Rainbowfish – No matter which tank mates you’re going for, you should always consider having a school of Rainbowfish. These fish are not that big, so a school of 6-8 Rainbowfish won’t require such a massive tank investment. The benefits of keeping the Rainbowfish in a proper school are immense since the fish will be more peaceful, calm, and more energetic overall.

Based on these factors, some compatible tank mates include angelfish, Corydoras, danios, mollies, platies, swordtails, tetras, and others.

You can also pair the Rainbowfish with species that don’t share their swimming space. Rainbowfish are more active in the tank’s middle area, so they make for great partners for bottom-dwellers, for instance.

Plecos are a great choice since these fish will rarely if ever, leave their safe space near the tank’s substrate.

Rainbowfish Diseases and Treatments

Rainbowfish are mostly prone to the common diseases that plague freshwater fish. These include velvet disease, fin rot, and Ich, all of which are easily treatable in their incipient phases. Your Rainbowfish will display specific symptoms, depending on the disease’s profile.

Some signs to look out for include:

  • Stressed behavior, including lethargy, hiding behavior, and irritability
  • Lack of appetite for longer periods of time
  • Increased aggressiveness without any clear reason
  • Rugged and rotting fins
  • Body discoloration and skin peeling off
  • Swimming difficulties, etc.

If your Rainbowfish displays any of these signs, quarantine is the first necessary step. Relocating your fish into a hospital tank will contain the infection and provide the sick fish with adequate treatment.

Treating the diseases is pretty straightforward. Keep your fish’s water parameters crystal clear, perform daily partial water changes, and provide your fish with a nutritious and diverse diet.

If the fish’s condition is more advanced, the fish may refuse food for the first 2-3 days, which is normal. Make sure you quarantine the fish for at least 2 weeks to observe its progress and see if the treatment works.

If you’re dealing with a parasitic or bacterial infection, you may also want to treat the main tank.

Adding some salt and using antibiotics or a water conditioner are necessary to eliminate the parasites that may be floating in the water.

Just make sure to discuss with an experienced vet to prevent any complications and learn the proper dosages.

How Big do Rainbowfish Get?

Rainbowfish will grow up to 8 inches, but the fish’s size depends largely on its species.

Some species only grow up to 3 inches, others between 4 and 6, and some will reach 8 with optimal care and good genetic makeup.

If you want to boost your Rainbowfish’s maximum size and growth rate, I recommend:

  • Ensuring a diverse diet to provide the Rainbowfish with all optimal nutrients
  • Keeping your fish well-fed, providing 1-2 meals per day, depending on its appetite and size
  • Ensuring sufficient space, depending on how many fish you have
  • Choosing the Rainbowfish’s tank mates carefully to prevent aggression and fish stress
  • Keeping water parameters within the ideal values
  • Preventing diseases and ensuring immediate treatment at the first sign of sickness

Your Rainbowfish should live up to 8 years with proper care or even more in exceptional cases.

Are Rainbowfish Aggressive?

No, Rainbowfish are actually peaceful and docile fish that will get along with a variety of other fish species.

That being said, there are some relevant instances where your Rainbowfish will show its uglier side, mainly:

  • When there isn’t enough space – Rainbowfish require sufficient space to remain healthy, calm, and friendly in the long term. Overcrowding them will result in Rainbowfish growing more irritable and sparking territorial fights.
  • When there isn’t enough food – All fish will grow more aggressive if they don’t have sufficient food. Your Rainbowfish requires at least 1-2 meals per day to remain in top shape. Make sure all your fish get to eat properly to avoid any unexpected violence between them.
  • When there aren’t enough females – Keeping too many Rainbowfish males in one place is bound to degenerate into violence when there aren’t enough females around. Males display high competitiveness between them, especially when there are some females around. To mitigate the males’ behavior, always have sufficient females for all of them. At least 3 per male should do the trick.

Rainbowfish may also become more irritable when sick or experiencing digestive issues or parasites.

Otherwise, healthy and happy Rainbowfish will rarely display any violence, except for the situations I’ve already mentioned.

Is Rainbowfish Good for Beginners?

Yes, Rainbowfish is recommended for beginners. This fish is hardy, peaceful, and easy to care for, on par with guppies and other easy-going species.

You only need to provide Rainbowfish with sufficient space, keep their environment clean, and feed them properly, and they won’t ask for more than that.


Rainbowfish are some of the most beloved tank fish for several reasons.

These include:

  • Their incredible adaptability and resilience
  • The impressive color and pattern variety among different species
  • Their peaceful and docile temperament
  • Their ability to adjust to community tanks very easily
  • And their natural shoaling and schooling behavior, always putting up a spectacle in the tank

If you’re a fan of chill, hardy, and beautiful tank fish with easy-going personalities, you can’t go wrong with the Rainbowfish.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.

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