Rainbow Tetra Care (Nematobrycon lacortei): Diet, Tank Requirements & Breeding



The scientific name of the Rainbow tetra as first described by Weitzman & Fink in 1971 is Nematobrycon lacortei.


Nematobrycon lacortei

Rainbow tetras have quite an interesting appearance. Their bodies display multiple colors in a way that is reminiscent of a rainbow. Rainbows have a dark lateral line, which is not always very prominent. The finnage of Rainbows are generally reddish or transparent, with black margination. Their eyes may be red or white.

Rainbow Tetras are slightly sexually dimorphic. This means that there are observable differences between males and females. Males Rainbows tend to be smaller in size when compared to their female counterparts.

The size of rainbow tetras ranges widely, typically between 2.5 centimeters to 5 centimeters, or 1 to 2 inches.

Habitat & Tank Condition


The Rainbow tetras are best adapted for life in slightly acidic water, with pH values ranging between 6 and 7. To lower pH (and increase acidity levels), fishkeepers can use Indian almond leaves, pH buffers, peat moss, and driftwood.


The rainbow tetras should be kept in an aquarium where temperatures are within the range of 22 and 26 degrees Celsius (72 to 80 degrees Fahrenheits). Depending on where you live, you might need a heater to maintain adequate temperatures for your rainbow tetras.

To keep your warm-water Rainbows, we recommend Fluval-E or EHEIM Jager for most setups.

Tank size

The recommended tank size for the Rainbow tetra is 10 gallons. Even though tetras are not that big, nano aquariums are not going to be enough. Since tetras are a schooling fish, you must place them in a group of at least 6. 


A filter is recommended, to maintain the health of your fish.


Rainbow tetras are omnivores and typically are not picky eaters. It is recommended that you feed your tetras a varied diet, as this will provide the most nutrients and benefit their overall health. 

Dry foods like granules, flakes, crisps, pellets, and wafers are good choices. 

For protein, you may use frozen, freeze dried, or live foods like earthworms, daphnia (water fleas), bloodworms, tubifex, infusoria and brine shrimp.

Since Rainbow tetras are quite small, it might be helpful if you break up their food into smaller pieces. If the food is too big, the food can remain lodged in their mouth for quite some time and cause some discomfort for the fish. 

Your diamond tetras should be fed twice a day. 

Make sure not to overfeed them, as this can increase chances for disease and deteriorate water conditions. There should be enough for your fish to eat within 5 minutes. So, once you have put the food in the aquarium, if the fish is still eating after 5 minutes, then you have added too much food. 


Peaceful are the Rainbow tetras. When the right conditions are met, rainbow will not be aggressive towards other fish in a community tank. As was mentioned earlier, Tetras are schooling fish. If there are not enough tetras to form a school within the aquarium, they will become stressed and be more likely to be aggressive. This can be observed if you see your tetras nipping at other fish. To reduce the tetras stress level, you would in this case, add more tetras to the aquarium (minimum 6). If within a large school, tetras can evade predators and avoid conflict more easily.


To breed Rainbow tetras at home can be difficult. However, you can drastically increase your chances of success through a few essential steps.

Nonetheless, expect setbacks, as female tetras are not always willing to spawn, even when presented with the perfect opportunity.

To begin this process, prepare a separate aquarium for your breeding pair. The aquarium should have a lot of plants for the female to spawn onto. Plants will also provide shelter to the Rainbows, who are more likely to spawn when they feel most at ease.

The aquarium water should have a slightly acidic level, generally between 6 to 6.5. Water hardness should be low, preferably between 1.5 dGH.

Once you are ready, place the breeding pair in the aquarium while leaving the lights closed. Maintain the fish in darkness for a day or two. You may want to cover the sides of the aquarium to prevent light from entering.

After then, begin to slightly increase the amount of light in the aquarium daily. The fish will eventually spawn.

The eggs of Rainbow tetras are adhesive so you should be able to see them attached to plants, rocks and sometimes the glass of the aquarium.

Remove the parents from the aquarium soon after they have spawned, to prevent them from eating the eggs.

Generally, the eggs of Rainbow tetras will hatch 24-48 hours later. Expect a 25 to 50% hatch rate.

Hatchlings will remain within or near the egg for a period of 24 to 48 hours to feed on the yolk sac.

Once the fry has begun to swim about the aquarium, feed them small foods. Infusoria, or commercially available prepared foods for fry fish are a good choice.

It is only a few weeks later that the fry will be able to swallow bigger foods, like brine shrimp.

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