The Bright and Beautiful Rainbow Tetra – A Comprehensive Care Guide

A beginner’s guide containing everything you need to know about keeping Rainbow Tetra fish happy and healthy.

Rainbow Tetra – Quick Facts

Fish Info

Scientific Name Nematobrycon lacortei
Family Characidae
Appearance A stunning rainbow multicolor with red and blue being more dominant, along with shades or yellow and orange.
Difficulty Beginner/Intermediate
Distribution San Juan River basin, Western Columbia, South America
Lifespan 3 – 5 years
Shoaling Yes
Temperament Relatively peaceful but can be feisty!
Keep in Groups of 8 or more
Tank Mates Other tetras and schooling fish
Diet Omnivore
Length 2.5 – 5cm
Sexual Dimorphism
  • Males have long dorsal and caudal fins than females.
  • Males have red eyes and are more colorful. Females have blue/green eyes.
Breeding Difficulty  Beginner/Intermediate

Water/Tank Recommendations

Water Temperature 76 – 82 °F (24.4 – 27.8°C)
Water pH 5.0 – 7.2
Water Hardness 5 – 8 GH
Tank size 15 – 20 gallons (20 – 30, ideally)


The Rainbow Tetra is a friendly little freshwater fish that has been popular for quite some time. They’re extraordinarily pretty, very hardy, and quite easy to care for, which is why they are popular among aquarists of all experience levels, from beginner to pro. Due to their popularity, you’re very likely to find them for sale at your local tropical fish center.

NOTE: Many people assume that rainbow tetra and neon tetra are the exact same species. However, this is not true! Although rainbow tetra fish are somewhat neon in appearance, Neon tetras are similar fish but they are a different species.

But despite their popularity, there is still much misinformation about these fish floating around the aquarium community! We know this because we hear from people who think certain things about them (and it’s not always right).

This guide will set the record straight while also providing you with everything you need to know if you want to own one as a pet. By the time you finish reading it, you’ll be an expert.

About Rainbow Tetra

The rainbow tetra is a little, colorful and active freshwater fish species. It’s part of the Characidae family, which includes over 900 different types of fish!

The name “tetra” comes from its scientific classification. Tetras are very social creatures that live in large groups (shoals) within their natural environments. Thus, they do well with others and form shoals that swim throughout your tank.

They are relatively easy to breed for the aquarist looking for species that do well in captivity. Thanks to their popularity with hobbyists around the globe, this is a fish whose needs have been understood for decades.

Who discovered the rainbow tetra?

The rainbow tetra fish was discovered by Alexander von Humboldt in 1805. Von Humboldt was a German explorer.

What is the natural habitat of the rainbow tetra?

Rainbow tetra fish are native to the Amazon River Basin in South America.

TIP: Rainbow tetras are native to South America. They can be found in the San Juan River basin in Western Columbia and its tributaries.

This river basin features slow-moving waters with lots of natural vegetation, so you’ll find that Rainbow Tetras prefer this kind of habitat when kept in a tank.

Their Length

The average Rainbow Tetra length is quite little at somewhere between 2.5 and 5 cm. However, there have been reports of these fish reaching lengths up to 36 cm.

The size of this fish can be affected by several factors, including genetics and the quality of care they receive while growing up.

The growth rate of Rainbow Tetras is relatively fast, making it essential to provide them with a large tank as juveniles. This will help them reach their full potential and live a healthy life.

How big do rainbow tetras grow in the wild?

In the wild, they can grow up to around 9 cm, with some exceptions growing far larger.

How big do rainbow tetras grow in captivity?

In captivity, they won’t grow quite as large as they do in the wild, with most reaching up to around 5 cm in length.


On average, the lifespan of a healthy Rainbow Tetra is around three to five years. There have been reported instances where fish have lived longer than this, but it’s not common.

As always, there are no guarantees when it comes to life expectancy. Fish living in poorly maintained environments or in numbers that are too low could experience health issues and die much sooner than expected.

Where can I buy rainbow tetras?

You should be able to find these fish in your local pet or fish store. Online aquarists will also often stock rainbow tetra, especially if they stock other tropical fish.

TIP: To help your Rainbow Tetras reach the max lifespan possible, you have to provide them with a clean environment, with lots of friends (8+) and top-notch care. That commitment will not only keep your fish healthy but also bring joy to your viewing experience!

Caring for Rainbow Tetra

If you want to purchase a healthy Rainbow Tetra, you should take care of them properly once they are in your tank. Fish raised in substandard conditions often suffer from health issues, even when moved into better living quarters. That said, these fish are very hardy.

To prevent this from happening, get fish from a seller with good reviews (of course). They will most likely sell fish raised in clean tanks with solid water quality. If reviews are questionable, look elsewhere!

Once you bring your new Rainbow Tetra home, quarantine them in a separate tank for at least 30 days. This helps the fish get used to their new environment while preventing any potential illness from spreading into the rest of your aquarium.

Aquarium Size

The recommended minimum tank size for Rainbow Tetras is 15 to 20 gallons. However, we recommend a slightly larger aquarium if you can manage it (20 to 30 gallons).

These fish prefer living in large groups and need ample space to swim around. Plus, they do best when kept with other compatible species. A larger tank will help keep the water clean and reduce stress for your fish.

TIP: As always, if you want to keep more than one species together in the same tank then increase the size of your aquarium accordingly.

Water Conditions

Rainbow tetras do well in standard tropical conditions. They’re not as fussy as some other fish species. However, you have to meet their basic needs and provide a stable environment that meets their unique requirements.

The pH level should fall within 5.0 to 7.2 (aim for around 6.5), and water temperatures should be between 76 degrees and 82 degrees Fahrenheit (24.4 – 27.8°C), with around 76 to 78 being ideal. Though they can live in slightly cooler waters than many tropical fish, don’t take this fact lightly!


Rainbow tetras are omnivores. In the wild, they feed on plants and small invertebrates in their natural habitat.

In captivity, you can provide them with a well-balanced protein-rich omnivore diet. Give them dried foods like flakes or pellets for daily snacks and meals. You can also offer live, frozen, and freeze-dried foods as supplements to their diet.

They love bloodworms, daphnia, fruit flies, brine shrimp, and other nutritious treats.
These foods provide them with a source of high-quality protein that will help the fish stay healthy.

TIP: It’s also important to avoid overfeeding these fish! Rainbow tetras can get fat just like other species, so limit food to what they can eat in a couple of minutes.


Rainbow Tetras aren’t prone to significant health issues in a pristine environment. However, they can experience some common fish diseases like all freshwater species.

The most prevalent ailment is Ich. Also known as White Spot Disease or white plague, this condition causes tiny white spots to form all over your fish’s body. If not treated quickly, white spot disease can kill an entire tank full of fish within only a few days!

Another issue you may encounter is fin rot. This fungal infection affects the delicate fins and can lead to severe problems if left untreated. Unfortunately, it’s often accompanied by bacterial infections and parasites as well.

Behavior and Compatibility

One of the biggest things to remember about these fish is that they are shoaling fish (social). This means that you should never keep them alone and should keep them with at least eight fellow rainbow tetras or similar shoaling fish. These colorful creatures will swim together throughout the day until it’s time to eat, which usually occurs just before dusk.


Mostly peaceful and playful, the Rainbow Tetra gets along with other non-aggressive fish. However, they are schooling fish, so they should be kept in groups of at least eight.

They like to play and dart around the tank together. However, a larger group of Rainbow Tetras tends to get feisty every once in a while, so make sure you have enough space for all your fish!

Rainbow Tetras don’t have the best eyesight. Most of their time is spent darting around in groups and playing with each other. They may ignore slower-moving fish that they can’t catch.

Tank Mates

Regarding other species of fish, Rainbow Tetras do fine with peaceful community tanks. However, they tend to be food for larger or more aggressive fish. They shouldn’t be kept with large cichlids or catfish because they might mistake them for food.

They can get along with other types of Tetras, Guppies, Mollies, and many standard tropical fish. However, they do not play well with slow-moving fish that they can’t catch.

TIP: You can tell the difference between male and female Rainbow Tetras pretty easily. Males tend to have longer fins, and more vibrant colors than females, along with red eyes.


Breeding Rainbow Tetras is a reasonably straightforward process. First, however, you’ll need to understand the spawning behavior of these fish to maximize your chances of success.

The adults are known to produce spawn more readily in tanks containing many plants which are more towards the acidic side in terms of pH.

Once successfully spawned, the female will lay her eggs on plants and then protect them fiercely afterward. One thing to note is that she may attempt to eat the eggs if she cannot find any suitable place to hide them! For that reason, many fishkeepers remove the eggs to a separate tank, so the parents don’t eat them.

Once they hatch, you can feed the spawn micro-food and baby brine shrimp until they reach maturity.

How many offspring do rainbow tetra fish usually have?

The rainbow tetra usually has around 10 to 30 babies. Bigger, healthier fish tend to have more offspring than smaller, less-filthy ones.

Should You Keep Rainbow Tetra Fish?

Rainbow tetra fish are a popular type of freshwater aquarium fish. They are relatively easy to care for and can add color and interest to your tank. However, there are some things you should know about before adding rainbow tetras to your home aquarium.


  • Hardy and relatively easy to care for
  • Can add color and interest to your tank
  • Generally peaceful and friendly, although they may nip at the fins of other fish species


  • Can be sensitive to changes in water conditions
  • They may not do well in tanks with other aggressive fish species


As you can see, Rainbow Tetras are among the most beautiful freshwater species. Even with their friendly, playful personalities and easy-care requirements, many aquarists find themselves mesmerized by the bright, pretty colors of these fish!

Now you should be an expert in rainbow tetra care. If you have any images you’d like to share of your own Rainbow Tetra, we’d love for you to send them our way or drop them in the comments below. Seeing how these fish look in different tanks never gets old!

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