Rainbow Tetra (Nematobrycon lacortei): A Complete Care Guide

rainbow tetra care

Extracting the inner beauty of the water world to the outer world is not an easy job without the proper knowledge. As one of my friends also had a problem regarding adding up fish some months ago. He added a rainbow tetra and was facing a lot of blunders on time. As I’m indulging in pisciculture, he consulted with me. Now he is no longer worried about this.

Today through this article, I’m going to share some important information about Rainbow Tetra. This article is all about how to keep fish like rainbow tetra safe and sound in every possible manner.

Simply after going through this article, you will be all clear about Rainbow Tetra’s origin, appearance, price, and lifespan. Adding further, their social behavior, disease, prevention, breeding, and tetra fish fry care are also clearly defined for you.

So all together you will come to know about how to give a Rainbow Tetra a favorable environment.

Fish Classification

Scientific NameNematobrycon lacortei
Common NamesRainbow Tetra
Origin / HabitatSouth America, Atrato and San Juan River basins.
Color FormThey have a beautiful multicolor, blue, and red being the dominant color.
Adult Size1.5 inches (4.2 cm)
Lifespan3 - 5 years
Fish Behavior/TemperamentSemi-aggressive
Water Temperature72°F - 80°F (22°C - 27°C)
Water Hardness5° to 8° DH
Water pHWater parameters: 5 - 8.0
Water MovementKeep the water movement moderate. Please don't make the water movement too much to make them continuously swim against.
LightingsRequires the lights to be on at least 9-10 hours a day. Light will aid them in maintaining their circadian rhythm.
Tank Region Middle to bottom can be quite active
TankmatesSemi aggressive and avoid fish with long fins to avoid fin nipping.
Diet and FoodOmnivore; accepts any form of food like live food, frozen food, flake food, and pellets.
Gender DifferenceMales have blue eyes, and females have green eyes.
Breeding DifficultiesSubstratum egg scatters. Reported to spawn more frequently in heavily planted aquariums on the slightly acidic side. Remove the eggs, so the parents don't eat them.
Tank SetupFreshwater[Planted]
DiseaseFish Lice, Tumors, Furunculosis, Fin and Tail Rot, Hole In The Head, Swim Bladder Disorder, White Spot Disease or ICH, Eye-Cloud / Cloudy Eyes, etc. Learn more about:- Tetra Fish Disease and Treatment.
Aquarium Size20 to 30 gallon recommended (schooling fish)

Introduction to Rainbow Tetra

The scientific name of Rainbow Tetra is ‘Nematobrycon Lacortei.’

Rainbow Tetra is a peaceful species of fish and rare in type usually found in sluggish tributaries, small quiet rivers. Though they are peaceful species they are sometimes territorial and may bully other fish if kept in small numbers. So you have to keep them in a group of 10 or more of its kind just to eliminate aggression between rival males.

Other than that, it properly jells up with Hemigrammus, Apistogramma, Anabantoids, and West African dwarf species.

Rainbow Tetra belongs to the Characidae family. It has many of the same traits as the Emperor Tetra. Usually, the size of the fish in captivity is 3-4cm (1.18 – 1.57 inch).

These tetras normally spend their time roaming around staying at the mid-level and surface level of the tank.

Rainbow Tetra is a kind of species of fish that is a bit tough to handle, but with proper knowledge and understanding level, everything is possible.

Origin of the Fish

Rainbow tetra originates from South America and is precinct to Western Colombia. Rainbow Tetra is a peaceful shoaling species mostly found in a small quiet river(Rio Calima) and a stream of the Rio San Juan basin. This species of fish was discovered in 1971 A.D by Weitzman and Fink.

Fish Appearance

Even though Rainbow Tetra has some similar traits like Emperor Tetra, other characteristics readily distinguish the species from each other.

Both species have long anal fins, club-shaped bodies, dark stripes.

The different character which makes Rainbow Tetra is it has every color (gray,)of the Rainbow. The dorsal fin is more triangular shaped and shorter in Rainbow Tetra. It has large eyes and is banded with red and orange.


Rainbow Tetras are rare fish. When available for sale, they are mostly wild-caught specimens at a size of ¾” to 1 ¼”.


Single Rainbow Tetra will cost you around 1 to 2 dollars. But as Rainbow Tetra species have to be kept in a group of at least six, it will cost you around 10 dollars mostly.


The lifespan of Rainbow tetra is probably dependent upon your maintenance and caring in most cases. But the expected life span of Rainbow Tetra is approximately 3 to 5 years.

Sexual Differences

Adult males Rainbow Tetra has red eyes and broad dorsal, anal, and caudal fins than female ones. Adult females have blue-green eyes and are fuller-bodied than males, when gravid.

One of the easiest ways to distinguish a male and a female rainbow tetra is by looking at their body and color. Male rainbow tetra is much more colorful and has a small body as compared to females.

Social Behaviour and Tank-mates

Rainbow Tetra is a somewhat boisterous but generally peaceful community fish in nature. Although adult males are a bit aggressive and territorial to an extent, this behavior may only extend to similarly shaped species sometimes. It is perhaps due to well-maintained alongside synonymous – sized characters, lebiasinids, smaller loricariid catfishes, and non-predatory. That’s why you need to maintain at least a group of six similar Tetras to eliminate risk.

Read Full Article on Tetra Fish Tank Mates and Fish You Need To Avoid.

Fish Keeping Difficulty

You will have some difficulty when keeping fish or aquarium at your stay place for the first time. It’s not that easy to get the best things without any hard work or concerns.

Likewise, while keeping fish, you have to go through many difficulties at times, and awareness is needed for sure. To keep your fish healthy, you have to be aware of proper diet, caring, essential tools, possible disease, and their prevention as well.

Sometimes, you have to take some guidelines from the internet also. Other than that, the hard work and effort are somehow worthwhile as it all brings the inner beauty of the ocean to the outer world(your stay place).

Caring for the Rainbow Tetra

Adding up Rainbow Tetra in your aquarium, you need to be more concerned and aware. So here, you will know how to care for Rainbow Tetra properly.

Like humans need basic and additional needs like air, water, diet, and soon, fish also do need proper care.

As Rainbow is a bit rare and uncommon, proper caring might be tough. Caring Rainbow Tetra needs an experienced level, but no worries these guidelines of our will surely help you out with no doubt.

You can take care of your Rainbow Tetra by going through the following tips.

Fish Tank

This is the first thing you need to consider while taking the initiation of caring for your Rainbow Tetra fish.

The proper size of the aquarium plays a vital role in keeping your fish more flexible and easy. The need for aquarium tank size is directly proportional to the number of fish.

One inch of fish requires 1-Gallon of water Community Tank needs to be much bigger with no doubt. Bigger the size, better for fish. Proper aquarium tank size ensures your fish for its adequate space for movement and so on.

For starters, buy at least a 30-gallon tank, this will help to make much room for mistakes without harming your fish.


Setting up the correct lights for Rainbow Tetra might be confusing as it has many colors of the Rainbow itself. But Rainbow Tetra is best with subdued light and densely planted tanks.

Proper lighting and planted tank ensure a hiding place and plenty of aquatic plants to swim through for your fish. Well planted tanks provide enough light to the plants of the aquarium and ensure the adequate light need for plants too.

Overall proper lighting and dense plants are the second essential things for caring for your Rainbow Tetra as it helps to balance the ecosystem of aquariums also.

Decoration and Substrate

The perfect substrate for the rainbow tetra is the natural ones from its origin. A well natural-looking procurement might consist of a soft, sandy substrate with wood roots and branches placed. It is important for assuring natural looks and, most importantly, fulfilling plants with nutrition as well. It directly or indirectly helps to balance the ecosystem of the aquarium.

Talking about decoration, it’s not that important in comparison to the substrate. You can choose any decoration items just to make it more attractive, like driftwoods, as it allows fish to swim through it. You can add plenty of aquatic plants, stems, and large leaves for decoration. There are varieties of decoration items available for your aquarium just to add up extra beauty and attraction in your aquarium.

Rainbow Tetra Fish Diet

Basically, rainbow tetra is an opportunistic omnivore by its nature. Rainbow Tetras are not choosy in food, so you use a quality flake and supplement their diet with frozen and live foods. You can feed them frozen foods like chironomid larvae (bloodworm), Daphnia, Artemia. But you have to consider the fish are small so they cannot consume a lot of food. You should feed enough food that your fish will eat within the time of 3 minutes and remove the remaining uneaten. If not removed the uneaten ones, it will decay, and as a result, it will impact the whole ecosystem of an aquarium.

Read Full Article on Tetra Fish Diet.

Maintain Water Quality

It is one of the most vital and underrated things in fish keeping. But regular water change is very important in order to care for your fish. As human beings have to maintain hygiene, fish also need a hygienic environment for survival. Without the existence of proper quality of water, neither human beings nor fish can have good health undoubtedly. A fish having good quality water surely tends to live a longer and much healthier life than in comparison to vice-versa. Poor water quality water directly leads your fish to suffer from many fatal diseases and death as well. So the health of your fish is directly proportional to the level of hygiene of the aquarium. That’s why maintaining a good quality of water ensures the fish safe from many risks and leads your fish to a healthier life.

The water gets unhygienic due to many factors so far. The fish produce plenty of waste materials like excrete, uneaten foods. Due to this, the level of different chemicals like nitrates, ammonia, etc. rises and cannot be adequately filtered by your aquarium tank. So changing the water from time to time maintains the parameters to normal and brings it back to the normal appropriate level.

You can balance the quality of your water by the household things too. Some of them are listed below for you, which can make your work more easier:

  • Gravel vacuum
  • pH reader
  • Algae scrubber
  • Magnetic algae scrubber
  • Siphon

What are the Requirements For Maintaining The Tank?

Water temperature, water ph, filtration, and water maintenance are the key factors required for maintaining the tank properly. Let’s have a look at these in brief:

Water Temperature

Generally, water temperature for most of the tetra fish falls under a similar range. Though, the recommended and optimum water temperature for your fish(Rainbow Tetra) is 22-28 degrees celsius(71.6 – 82.4 Fahrenheit).

Water pH

Knowing the appropriate ph and hardness required for your fish is essential. The recommended pH range and hardness of water(DGH) for this species are around 6-7.2 and 4-17N (71.43-303.57ppm).

Water Filtration

To the point, filtration filters all the unwanted chemicals and waste from your water. Filtration absorbs all the mechanical as well as chemical waste and cleans the water by filtering. A powerful mechanical filter would probably disturb your fish swimming pattern. Thus a filter with a gentle flow like a sponge filter with nice biological filtration should add up. Without a proper filtration system keeping your fish risk free is somehow next to impossible. So you have to be a bit conscious and choosy while buying an aquarium filter as it matters a lot.

Water Maintenance

To maintain your tank water, you must change the water at least 10% of it within a week at any cost. There are a lot of factors that make water harmful, like a toxin, fish bio-waste, nitrate, which directly impact the aquarium nitrogen cycle. So you have to eliminate those and keep your eye on it as well from time to time. Then comes checking the level of pH hardness, ammonia, nitrite, phosphate, nitrate by using different test kits. If any inappropriate reading of level found, you have to act accordingly with the situation.

Fish Disease

Rainbow Tetra has good immunity and less probability of getting infected. But sometimes, due to factors like improper water parameters, poor water conditions result in low immunity in fish. As the immunity system of your fish gets imbalanced, the probability of getting infected from disease increases in fish. Rainbow Tetra is likely to get infected from fin rot, and ich disease from improperly maintained water quality.

However, if your fish suffers from poor quality water, you can try and cure it by changing a large amount of water. You have to maintain the proper water parameters as well. If you are aware of these kinds of things, your fish will be unlikely to go through the results from poor water quality.

Read Full Article on Tetra Fish Diseases and Treatments.

Breeding Rainbow Tetra Fish

Breeding rainbow tetra is not as hard as you think if breed in the home aquarium. Small numbers of fry may appear at a time in a densely planted tank, but if you want to raise a larger number of young, a separate aquarium should be set up obviously. The water should be soft and acidic with a ph between 5.5 – 7.0 and a water temperature of 80-82 degrees Fahrenheit. Using the freshwater also ensures the proper breeding of the tetra fish

You can add a lot of live plants as it increases the survival rate too. Placing a spawning mop or some dense floating plants and keeping the light will be the best things to do during the time of breeding of rainbow tetra. Usually, they breed in the night time and a darker place.

Breeding Process

The best condition is if you separate male and female groups. When the female ones gravid a single pair should be selected and transferred to the separate small aquarium in the evening, with the spawning process starts to occur in the morning. Spawning process may continue for several hours as eggs are deposited in small batches. If you don’t find eggs after days, also remove the fish and repeat the same process with another pair. The adult ones will eat their eggs if given a chance, so you have to remove post-spawning. The eggs typically hatch in 24-35 hours, with the fry starts to be seen swimming like in 4 to 5 days.

Caring For The Fry

Like a baby human needs special care, fish fry also needs proper care in the beginning. As fish fry hatches, they are small and have a low metabolism rate. So you have fed fish fry on an infusoria-grade food for the first week or until they are bigger enough to accept the micro worm Artemia nauplii and so on. Proper diet and well care surely ensure the good health of your fish fry.


To keep your fish in the best condition, you need to keep these things in mind. If you are going to add up fish after knowing everything that it needs, the job will be a lot easier and stress-free. If you act on things according to proper information, everything in this world is easier, but if not, then everything is hard.


Image Credit: https://www.flickr.com/photos/42097281@N06/ (snailosyd)

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