Cochu’s Blue Tetra Overview, Care & Breeding Guide

Blue tetra fish is popular in the aquarium trade for being avid swimmers. It is an excellent choice for anyone that wants a lively and brightly colored peaceful fish for their community tank.

Its body looks smooth like velvet, as the scales are hardly visible, which results in its breathtaking glowing features.

The species is known to be one of the few vividly blue-colored fish available.

So, if you want to include this fish in your tank, keep reading!

What is Cochu’s Blue Tetra?

Cochu’s Blue Tetra is a blue colored freshwater fish that is a great choice for home aquarium keepers. Below are some more characteristics of these fish:

OriginAmazonian River basins, South America
Scientific NameBoehlkea fredcochui
Common NamesBlue tetra, blue king tetra, Cochu’s blue tetra
IUCN Red List StatusNot Evaluated
AppearanceLavender head, silvery blue body (darker on the back and lighter on the bottom) with pink hue at places.
SizeUp to 5.0 cm (1.96 in) in the wild, Up to 3.8 cm (1.5 in) in the captivity
LifespanUp to 3 years
TemperamentPeaceful, gregarious, shoaling
Tank LevelMiddle-level dwellers
Water Temperature72-82 °F (22-28 °C)
pH Level6.0-7.5
Water Hardness2-10 dGH
Care LevelModerate
Minimum Tank Size30 gallons for 6 of them
Tank EnvironmentTank with lots of space to swim and hide
DietCarnivorous, planktophage, but can thrive on an omnivorous diet
Tank MatesOwn species, peaceful, fast, and short-finned species

What is the Natural Habitat of Cochu’s Blue Tetra?

The freshwater fish is found in the Amazonian River basins of South America, which mainly covers Brazil, Colombia, and Peru’s River Maranon. More precisely, it inhabits the benthopelagic zones of tropical freshwater.

Which family does Cochu’s Blue Tetra come from?

The fish falls under the Characidae family of the Characiformes order. Its official scientific name is Boehlkea fredcochui, but some also called it Mycrobrycon fredcochui.

Commonly, it’s known as blue tetra and blue king tetra in the aquarium trade. But it also got an interesting name – Cochu’s blue tetra. This name was honored after Ferdinand Cochu, a tropical fish importer, introduced it to the aquarium culture (1956).

Fun Fact: It is a brilliant jumping fish, so if any other species tries to bully it, it jumps to escape from predators.

How does Cochu’s Blue Tetra look?

Albino king blue tetra

Similar to most tetras, its body is bilaterally symmetrical and oval. But let’s get down to some deeper facts.

What is the Size of Cochu’s Blue Tetra?

In the wild, the fish might be as long as 5.0 cm (1.96 in). But in the aquarium, its stunted growth allows the adult fish to be only 3.8 cm (1.5 in).

What is the Color of Cochu’s Blue Tetra?

The color of the fish is not uniform throughout its body. It has a silvery blue hue that fades out in some places and darkens in others.

On its lateral line, you will notice a blue horizontal line. Its caudal fin also has a dark spot. You may also rarely see a pink shade at its tail base. The fish eye is dark blue with a pop of pink.

Its color is more vivid towards that back, and it’s more transparent in the remaining areas. The head is nearly lavender shade.

What are other features of Cochu’s Blue Tetra?

The fish has a curved tail, translucent fins, otoliths auditory system, and lens eyes visual system. Its hearing range is 200-2000 Hz, and its hearing threshold is 70 dB.

Its mineralized skeleton contains apatite, and mineralized tissue contains aragonite and hydroxylapatite.

What is the difference between a male and a female Cochu’s Blue Tetra?

The male fish has a relatively slender and streamlined body with vibrant colors. The female fish is comparatively much broader around the belly. It isn’t as streamlined, and the colors are much more muted.

How do Cochu’s Blue Tetras behave?

The fish is peaceful and sociable around other species. However, this applies only if it has a large enough shoal (group of 6 or more) and enough space to itself. Otherwise, it may get stressed and act like fin-nippers to other tank mates.

What is the Lifespan of Cochu’s Blue Tetra?

In captivity, the fish usually survives for 2-3 years. However, in my research over the past 7 years, I noticed that the fish can be sustained for 4 years with optimum maintenance.

Author’s Note: Avoid housing other middle-level swimming tank mates. If no fish comes near it, this will reduce the chances of activating fin-nipping behavior.

How to take care of Blue Tetra?

Group of blue tetras

To ensure that your pet fish stays healthy and doesn’t harm its tank mates, maintain the following:

What Tank Size is recommended for Cochu’s Blue Tetra?

The fish needs a group to survive, so a minimum of 6 conspecifics (same species) need a 30-gallon tank.

However, if you house more than 6, use a 40-gallon tank.

What type of Water Chemistry should be kept for Cochu’s Blue Tetra?

The water parameters can impact your fish’s mood a lot. So, pay special attention to this list:

  • pH Levels: 6.0-7.5
  • Water Temperature: 72-82 °F (22-28 °C)
  • Water Hardness: 2-10 dGH
  • Carbonate Hardness: 2-4 dKH
  • Ammonia: 0 ppm
  • Nitrite: 0 ppm
  • Nitrate: Below 30 ppm

What is the Tank Environment for Cochu’s Blue Tetra?

A balanced environment alone may make your fish feel on the edge. So, you must also decorate it properly with the following:

Do you need Substrate for Cochu’s Blue Tetra?

Use a darker substrate to mimic its native habitat, highlight the fish’s color, and make it feel safer with dim light. You can choose either fine sand, gravel, or soil to suit the needs of your bottom dwellers.

Do you need Plants for Cochu’s Blue Tetra?

Add plants to create a shaded space but keep enough swimming space.

What type of Lighting is needed for Cochu’s Blue Tetra?

Use dim lights to ensure that the fish feels protected and secure.

What type of Décor is needed for Cochu’s Blue Tetra?

Add enough rocky structures like caves and branches to increase the darkness. Add driftwood and dry Indian almond or guava leaves to stain the water with tannins and maintain an acidic environment.

You can also add Malaysian, Neka, Spiderwood, or Pacific wood and cones of Birch, Casuarina, Alder, or Giant Alder.

Which filter should you use in an aquarium for Cochu’s Blue Tetra?

Use a gentle sponge water filter to sustain a healthy ecosystem. Otherwise, the strong current of the filter might disturb the fish from swimming on its own.

What should be the Water Flow Rate for Cochu’s Blue Tetra?

The fish likes extremely slow water flow, so choose a gentle flow that is almost stagnant but still moving.

Fish Care Tip: If it gets nippy (nips other fish’s fins), even if all the demands are met, feed it immediately. It might be a sign of hunger.

Which Food do Cochu’s Blue Tetra Eat?

In the wild, the fish greedily feast on plankton (larvae, small crustaceans, etc.) and mainly carnivorous food sources.

However, it is not a picky eater. It will thrive on anything you provide but ensure a healthy and balanced diet of good quality feed consisting of live, frozen, and freeze-dried food. You can choose a variety from this list:

  • Micro pellets
  • Flakes
  • Granules
  • Mosquito larvae
  • Tubifex worms
  • Bloodworms
  • Cyclops
  • Daphnia
  • Brine shrimp
  • Dead plants
  • Algae wafers
  • Chopped soft fruits

What are the recommended Tank Mates for Cochu’s Blue Tetra?

Before you add any other species, ensure there are at least 6 blue tetras in your tank. Other than that, you can also add any peaceful and similarly-sized species, including:

Which Tank Mates should you avoid to keep with Cochu’s Blue Tetra?

To protect all species in your tank, you must not house the following types with a blue tetra:

  • Bigger species: They might feast on your blue tetras:
  • Aggressive species: They might bully and injure your fish
  • Slow-moving fish: Blue tetras are pretty fast swimmers, which can stress the slower ones and even feast on their food first
  • Fish with long fins: If the tetra gets stressed, it might nip on their fins
  • Other middle-level swimmers: If the tank gets too congested in the middle water levels, it might stress blue tetras and make them prone to sickness
  • Small invertebrates: They will become food for the fish

Some specific fish that can’t be kept together with this species are:

  • Bettas
  • Guppies
  • Freshwater angelfish
  • Harlequins

What are the Common Diseases to look out for Cochu’s Blue Tetra?

The fish is pretty hardy and resistant to most diseases. But owing to the fluctuating tank environment, it sometimes becomes sensitive to illnesses like…

Disease NameCausesSymptomsTreatment
ColumnarisBacterial infectionGrey to white patches, frayed fins, inactivity, no appetiteEnhance water quality, reduce stress causes, antibiotics
IchParasitic protozoan infectionFlashing, white spots, inactivity, no appetiteRaise the temperature, add ich medicine or aquarium salt
Fin rotBacterial infectionFrayed/disintegrated fins, fin discoloration or red streaks on fins, inactivity, no appetiteEnhance water quality, remove physical injury causes, antibiotics
Swim bladder diseaseConstipation, overfeedingAbnormal swimming patterns, inactivity, no appetiteReduce meal portions, feed them only boiled and skinned peas.
Neon tetra diseaseMicrosporidian parasitic infectionLoss of color, hyperactivity, lumped flesh, spine curved, abnormal swimming, bloating, fin rotIncurable Prevention is the best option Try treating with methylene blue

You can prevent most diseases in your pet fish by following these steps:

  • Change 10% water weekly
  • Maintain a steady temperature and pH
  • Use the best filters and test kits to maintain a toxin-free environment
  • Feed them good quality food only
  • Always quarantine your new fish

How to Breed Cochu’s Blue Tetra?

There are moderate to low chances of breeding this fish. Moreover, not much info is recorded about breeding them. So, to maximize the chances, you need to follow certain rules.

What does a Breeder Tank Setup for Cochu’s Blue Tetra look like?

Set up a separate tank with the following parameters:

  • Water Temperature: 75 °F (24 °C)
  • pH Level: 6
  • Water Hardness: Consistently soft as blue tetras specifically reproduce in soft water.
  • Lighting: Dim
  • Plant: Plants with fine, smooth, and broad leaves help catch the eggs. It also helps protect and hide the fry from the parents as they might eat them. Add floating plants as well to diffuse the light further.
  • Decor: Spawning mop for added security to the eggs.
  • Filter: Filtration is not mandatory, but if used, only go for small sponge filters.


Feed high-grade feed to the tetras until the males show their brightest colors and the female grows broader. Introduce the group to the tank after a few days.


The female fish scatters her eggs on the underside of flat and long leaves, spawning mops and substrate. The male fertilizes the eggs.

Parent Removal

Put the parent fish back in their tank once you notice the eggs. Otherwise, they may eat their fry as soon as they see them.

When do Cochu’s Blue Tetra eggs hatch?

Depending on the tank conditions, the eggs hatch after 2-3 days. Until the fry free themselves entirely from their egg sac, don’t feed it. They live on their egg yolk sac for some time.

Once they become free swimmers, feed them micro or chopped fry food, fine and crushed flake food, baby brine shrimp, or infusoria.

If the tank has enough plants, the fry will also feed on them.

Breeding Tip: Watch the unhatched eggs closely for parasitic infestation. Remove any egg that seems to be affected to protect the others.

What are the buying tips for Cochu’s Blue Tetra?

1. The name “blue tetra” is used to refer to many other species like

  • Knodus borki: aka blue tetra or blue peru tetra. It has more teeth than Boehlkea fredcochui and much lesser scales on its lateral line.
  • Paracheirodon simulans: Commonly called green neon tetra, but also called blue tetra in some regions of the world

So, be careful while buying the Boehlkea fredcochui.

2. If you go to a shop to buy this fish, tell them about your tank dimensions and existing fish. They may warn you against purchasing this species if you don’t have the proper setup. You can further discuss what setup you need.

A word from FishInAquarium

If you get your hands on a group of these uncommon fish, you can build a unique and attractive tank. Beginners can also improve tank maintenance skills while keeping up with this hardy fish’s needs.

So, if you’re satisfied with the information in this think-piece, don’t forget to share the article with other hobbyists. And if there are more questions, write us a mail, and we promise to come back with an answer!

Minnie B Miller - Professional aquarist and owner of FishInAquarium

About Minnie B Miller

Minnie B. Miller, a professional aquarist and owner of FishInAquarium, has over 8 years of expertise in fish breeding and care, gained through her roles at AquaticTX and Sea Lion Landing. Having honed her skills with various aquatic species, she is dedicated to empowering fellow enthusiasts by sharing her knowledge and experience.