Information, Characiformes (Characins), Freshwater fish, Species, Tetras

Redeye Tetra: Complete Species & Care Overview

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by Jason Matthews



Redye Tetra is a freshwater fish species originating from South America. This fish species is known for its striking silver body that stands out in an aquarium and the presence of a unique red spot on its iris. It is a friendly fish and is perfect for beginners due to its hardy nature. 


Scientific Name: Moenkhausia sanctaefilomenae
Common Names: Redeye Tetra, Yellowhead tetra, Lamp eye tetra
Life Expectancy: 5 years
Adult Size: 2.75 inches


Origin South America
Care LevelEasy
Temperament Friendly and social
Diet Omnivore
Tank LevelMid-dweller
Water pH5.5 – 8.5
Water Temperature73°F – 82°F
Water Hardness5 dGH – 20 dGH
LightingDim or subdued
Tank MatesOther tetras, larger rasboras, danios, rainbowfish, barbs, guppies 

Fun Fact Corner

  • Redeye tetras are bred extensively for aquarium purposes, in Asia today. 
  • Redeye tetras are also known as lamp eye tetras due to the presence of a prominent red spot on their eye that contrasts their silver body.


Redeye tetras (Moenkhausia sanctaefilomenae) originate from the tropical waters of South America. They are distributed across various regions, mainly – Western Brazil, Paraguay, Eastern Bolivia, and Eastern Peru.

In the wild, this fish species is either found in clear streams or murky waters of the Amazon. 


Redeye tetras are mostly friendly and can thrive well with other tank mates! However, it would be best if you kept them in groups of six or more

If you keep a single redeye tetra or very few redeye tetras together, they may exhibit aggressive behavior. In fact, a single redeye tetra is known to nip the fins of fish species with long and delicate fins!

On the other hand, a group of six or more redeye tetras is pretty active and social. It’ll swim around the whole tank rapidly. Their overly social and active nature might sometimes create some problems for slow-moving fish species. 


Most redeye tetras can live up to five years of age. However, you must give them proper care and maintain the tank well to prevent premature death. 

Size and Appearance

Redeye tetras
Image: kazakovmaksim, depositphotos

Redeye tetras are typically larger than most other tetras. This beautiful fish species can grow up to 2.8 inches in size. On infrequent occasions, they may even reach 3 inches. 

Body Shape

Redeye tetras have a basic tetra-style oval shape. The overall body is somewhat flat whereas the middle portion is more rounded.  

Body Color and Markings

Redeye tetras possess a striking silver color. Their bodies are covered with shimmering scales, making them stand out in an aquarium. Some redeye tetras also have slight yellow markings on their silver scales. 

This fish species have beautiful transparent fins. There is an elongated anal fin present as seen in most tetra species. You’ll find a little adipose fin on the top too!

The forked caudal fin has accentuated black near the tips with white color outlining it. This gives a lovely and unique shaded effect to their caudal fin. 

However, the standout feature is their eyes. The top portion of their irises has a red spot, whereas the rest of the area is silver and matches their body color. Due to this red spot, they are known as the “redeye tetra”.

Differences Between Male and Female Redeye Tetra

Male and female redeye tetras show certain levels of sexual dimorphism as presented in the table below. 

CategoryMale Redeye TetraFemale Redeye Tetra
Body SizeSmaller and sleekLarger and rounded
Body ColorMore vibrant during the breeding periodSlightly less vibrant 
Dorsal finPointedRounded


Breeding is relatively easy in redeye tetras. You need to create a separate breeding tank and introduce around 12 redeye tetras.

  1. Prepare a 20-gallon breeding tank with slightly acidic water conditions (5.5-6.5) and soft water (below 4 dGH). It is also preferable to keep slightly warmer water temperatures (between 80°F and 84°F). 
  1. Keep several leafy plants in the breeding tank for the eggs. Also, don’t forget to add java moss and spawning mops.
  1. Introduce the male and female redeye tetras in the breeding tank in the evening. Allow them to breed overnight.  
  1. During spawning, male and female redeye tetras lock fins and roll over in the plants.
  1. By the morning, the female redeye tetras will release the eggs. 
  1. Once the eggs are fertilized, remove both the male and female redeye tetras as they may feed on the eggs. 
  1. The eggs will hatch within 36 to 48 hours. Once they do, the fry will feed on the egg sac. 
  1. You can provide the fry with typical fry food or infusoria and then shift to newly-hatched brine shrimp. 

Nutrition and Diet

Redeye tetras are omnivores. In the wild, they feed on quite a lot of things, including both insects and plants. Therefore, you can choose from a wide range of items to feed them. 

You can consider feeding them high-quality pellets and flakes daily. The table below also mentions some of the best live/frozen food and vegetable options for your redeye tetras. 

Frozen/Live FoodBrine shrimp, bloodworms, tubifex worms, and daphnia
VegetablesSpinach, peas, cucumber, and carrots

Keep in mind that you need to feed redeye tetras at least twice or thrice a day

Ensure that you give them only as much food as they can consume in three minutes! If there is leftover food in the tank after three minutes, then you might be overfeeding them. 

Tank Requirements

Redeye tetras are mid-dwellers. They can tolerate and adapt to a range of water conditions, right from slightly acidic water to alkaline water. 

Tank Size

Redeye tetras are slightly larger than other tetras. They are also active swimmers and require more space to swim around freely. Therefore, you need at least a 20-gallon tank to house a school of six redeye tetras

Water Requirements 

Redeye tetras need warm and slightly neutral pH water conditions. 

  • Water Temperature – Redeye tetras prefer tropical temperatures. So, the water temperature should be kept between 73°F and 82°F.
  • Water pH – Keep the pH between 5.5 and 8.5, preferably around 7.
  • Water Hardness – It should be between 5 dGH and 20 dGH.
  • Water Flow – Redeye tetras prefer a stagnant water flow. So, keep the currents extremely mild.  

Decoration and Plants 

When it comes to decoration and plants, try to mimic the natural environment of redeye tetras. As they belong to the lush rivers of South America, you need to provide them with sufficient shade, vegetation, and hiding spots. 

You can keep rocks and driftwood in your tank. Additionally, you should also add some common aquarium plants for redeye tetras like java fern, hornwort, Anubias, Vallisneria, and Amazon Sword

Redeye tetras are mid-dwellers. So, it isn’t necessary to pay special attention to the substrate. But, it is best to opt for a dark substrate (like dark/black gravel) to mimic their natural habitat. 


Redeye tetras originate from the heavily-vegetated streams of South America. Therefore, they require either dim lighting or no lighting at all. 

You can offer them dim or subdued lighting by keeping floating plants to scatter the tank lighting. 

Best Tank Mates

Redeye tetras are usually friendly and unproblematic. You can pair them up with various other friendly fish species! 

I recommend opting for tank mates with a similar size and temperament as that of redeye tetras. The best ones are listed below. 

Keep in mind that redeye tetras are active and swim around fast. They might also engage in fin-nipping (if kept alone). So, it is best to avoid keeping fish that swim slowly or have delicate and long fins, with redeye tetras. 

You should also avoid keeping redeye tetras with aggressive fish species, like bettas, oscar fish, or cichlids


Jason Matthews

My name is Jason Matthews, and welcome to my website. When other kids were bragging about how their dog could sit and roll over, I was bragging about my latest Betta Fish and the cool sea castle I just added to his aquarium. 

Jason aquariume

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