Photo: Axel Zarske & D. Bork (CC BY 4.0) — via Wikimedia Commons
Cochu's Blue Tetra (Boehlkea fredcochui)
A shimmering, iridescent blue schooling tetra from the Amazon that brings a striking metallic flash to soft-water community tanks.
Will it live with a Cochu's Blue Tetra?
We compare each fish against your cochu's blue tetra on temperament, size, water parameters and swimming zone. Set your tank size and filter the results.
- Adolf's Cory✅ CompatiblePeaceful · 5.5 cm · Medium care · 22–26 °C (72–79 °F)
- Both are peaceful, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Adolf's Cory in a shoal of 6+ or it gets stressed and nippy.
- Axelrod's Cory✅ CompatiblePeaceful · 5 cm · Easy care · 23–28 °C (73–82 °F)
- Compatible on the things that matter: shared water near 23–28 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Axelrod's Cory in a shoal of 6+ or it gets stressed and nippy.
- Bandit Corydoras✅ CompatiblePeaceful · 5 cm · Easy care · 22–27 °C (72–81 °F)
- Both are peaceful, and their water overlaps around 22–27 °C — no size, zone or temperament conflicts.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Bandit Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Blue Turbo Snail✅ CompatiblePeaceful · 5 cm · Medium care · 25–30 °C (77–86 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Checkered Barb✅ CompatiblePeaceful · 5 cm · Easy care · 20–25 °C (68–77 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Checkered Barb in a shoal of 6+ or it gets stressed and nippy.
- Cherry Barb✅ CompatiblePeaceful · 5 cm · Easy care · 23–27 °C (73–81 °F)
- Compatible on the things that matter: shared water near 23–27 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Cherry Barb in a shoal of 6+ or it gets stressed and nippy.
- Chocolate Gourami✅ CompatiblePeaceful · 5 cm · Hard care · 25–30 °C (77–86 °F)
- Compatible on the things that matter: shared water near 25–28 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Chocolate Gourami in a shoal of 6+ or it gets stressed and nippy.
- Firehead Tetra✅ CompatiblePeaceful · 5 cm · Medium care · 24–28 °C (75–82 °F)
- Both are peaceful, and their water overlaps around 24–28 °C — no size, zone or temperament conflicts.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Firehead Tetra in a shoal of 8+ or it gets stressed and nippy.
- Five-banded Barb✅ CompatiblePeaceful · 5 cm · Easy care · 23–27 °C (73–81 °F)
- Both are peaceful, and their water overlaps around 23–27 °C — no size, zone or temperament conflicts.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Five-banded Barb in a shoal of 6+ or it gets stressed and nippy.
- Forktail Blue-eye✅ CompatiblePeaceful · 5 cm · Easy care · 22–28 °C (72–82 °F)
- Compatible on the things that matter: shared water near 22–28 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Forktail Blue-eye in a shoal of 6+ or it gets stressed and nippy.
- Half-striped Penguin Tetra✅ CompatiblePeaceful · 5 cm · Medium care · 23–28 °C (73–82 °F)
- Compatible on the things that matter: shared water near 23–28 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Half-striped Penguin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Harlequin Rasbora✅ CompatiblePeaceful · 5 cm · Easy care · 23–28 °C (73–82 °F)
- Both are peaceful, and their water overlaps around 23–28 °C — no size, zone or temperament conflicts.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Harlequin Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Honey Gourami✅ CompatiblePeaceful · 5 cm · Easy care · 22–28 °C (72–82 °F)
- Compatible on the things that matter: shared water near 22–28 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Horseman Cory✅ CompatiblePeaceful · 5 cm · Medium care · 22–26 °C (72–79 °F)
- Compatible on the things that matter: shared water near 22–26 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Horseman Cory in a shoal of 6+ or it gets stressed and nippy.
- Japanese Trapdoor Snail✅ CompatiblePeaceful · 5 cm · Easy care · 10–28 °C (50–82 °F)
- Compatible on the things that matter: shared water near 22–28 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Julii Corydoras✅ CompatiblePeaceful · 5 cm · Easy care · 23–26 °C (73–79 °F)
- Both are peaceful, and their water overlaps around 23–26 °C — no size, zone or temperament conflicts.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Julii Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Masked Corydoras✅ CompatiblePeaceful · 5 cm · Easy care · 22–28 °C (72–82 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Masked Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Mystery Snail✅ CompatiblePeaceful · 5 cm · Easy care · 20–28 °C (68–82 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Panda Corydoras✅ CompatiblePeaceful · 5 cm · Medium care · 20–26 °C (68–79 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Panda Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Rummy-nose Tetra✅ CompatiblePeaceful · 5 cm · Medium care · 23–29 °C (73–84 °F)
- Compatible on the things that matter: shared water near 23–28 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Rummy-nose Tetra in a shoal of 6+ or it gets stressed and nippy.
- Skunk Corydoras✅ CompatiblePeaceful · 5 cm · Easy care · 22–26 °C (72–79 °F)
- Both are peaceful, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Skunk Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Stoliczka's Barb✅ CompatiblePeaceful · 5 cm · Easy care · 20–26 °C (68–79 °F)
- Compatible on the things that matter: shared water near 22–26 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Stoliczka's Barb in a shoal of 6+ or it gets stressed and nippy.
- Xingu Black Neon Tetra✅ CompatiblePeaceful · 5 cm · Medium care · 24–28 °C (75–82 °F)
- Compatible on the things that matter: shared water near 24–28 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Xingu Black Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Zebra Danio✅ CompatiblePeaceful · 5 cm · Easy care · 18–25 °C (64–77 °F)
- Both are peaceful, and their water overlaps around 22–25 °C — no size, zone or temperament conflicts.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Zebra Danio in a shoal of 6+ or it gets stressed and nippy.
- Amano Shrimp⚠️ With cautionPeaceful · 5 cm · Easy care · 18–28 °C (64–82 °F)
- Cochu's Blue Tetra may eat Amano Shrimp or pick off its shrimplets — a densely planted tank with moss gives them a fighting chance.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Black Ruby Barb⚠️ With cautionSemi-aggressive · 6 cm · Easy care · 22–26 °C (72–79 °F)
- Expect Black Ruby Barb to harass Cochu's Blue Tetra at times; give dense cover and watch them at feeding.
- Your 75 L tank is below the ~100 L this pairing really wants — crowding raises aggression.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Black Skirt Tetra⚠️ With cautionSemi-aggressive · 6 cm · Easy care · 20–26 °C (68–79 °F)
- Black Skirt Tetra is semi-aggressive and may chase or nip the smaller Cochu's Blue Tetra — plant heavily and break up sight lines.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Black Skirt Tetra in a shoal of 6+ or it gets stressed and nippy.
- Desert Goby⚠️ With cautionSemi-aggressive · 6 cm · Easy care · 18–28 °C (64–82 °F)
- Desert Goby is semi-aggressive and may chase or nip the smaller Cochu's Blue Tetra — plant heavily and break up sight lines.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Dwarf Chain Loach⚠️ With cautionPeaceful · 6 cm · Medium care · 24–29 °C (75–84 °F)
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Dwarf Chain Loach in a shoal of 6+ or it gets stressed and nippy.
- Eastern Betta⚠️ With cautionSemi-aggressive · 6 cm · Medium care · 24–28 °C (75–82 °F)
- Expect Eastern Betta to harass Cochu's Blue Tetra at times; give dense cover and watch them at feeding.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- GloFish Tetra⚠️ With cautionSemi-aggressive · 6 cm · Easy care · 21–28 °C (70–82 °F)
- Expect GloFish Tetra to harass Cochu's Blue Tetra at times; give dense cover and watch them at feeding.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep GloFish Tetra in a shoal of 6+ or it gets stressed and nippy.
- Humpbacked Tetra⚠️ With cautionSemi-aggressive · 5 cm · Hard care · 24–28 °C (75–82 °F)
- Humpbacked Tetra and Cochu's Blue Tetra are close in size, but the semi-aggressive one tends to dominate — add cochu's blue tetra in a group to spread the pressure.
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Morse Code Corydoras⚠️ With cautionPeaceful · 5 cm · Medium care · 23–26 °C (73–79 °F)
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Morse Code Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Odessa Barb⚠️ With cautionSemi-aggressive · 6 cm · Easy care · 20–26 °C (68–79 °F)
- Odessa Barb is semi-aggressive and may chase or nip the smaller Cochu's Blue Tetra — plant heavily and break up sight lines.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Odessa Barb in a shoal of 6+ or it gets stressed and nippy.
- Peaceful Betta⚠️ With cautionSemi-aggressive · 6 cm · Medium care · 24–28 °C (75–82 °F)
- Expect Peaceful Betta to harass Cochu's Blue Tetra at times; give dense cover and watch them at feeding.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Silvertip Tetra⚠️ With cautionSemi-aggressive · 5 cm · Easy care · 22–28 °C (72–82 °F)
- Silvertip Tetra and Cochu's Blue Tetra are close in size, but the semi-aggressive one tends to dominate — add cochu's blue tetra in a group to spread the pressure.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Silvertip Tetra in a shoal of 6+ or it gets stressed and nippy.
- Smaragd Betta⚠️ With cautionAggressive · 6 cm · Medium care · 23–28 °C (73–82 °F)
- Expect Smaragd Betta to harass Cochu's Blue Tetra at times; give dense cover and watch them at feeding.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Spotfin Betta⚠️ With cautionSemi-aggressive · 5 cm · Medium care · 23–28 °C (73–82 °F)
- Expect Spotfin Betta to harass Cochu's Blue Tetra at times; give dense cover and watch them at feeding.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Striped Red-Eye Puffer⚠️ With cautionAggressive · 5 cm · Hard care · 24–28 °C (75–82 °F)
- Expect Striped Red-Eye Puffer to harass Cochu's Blue Tetra at times; give dense cover and watch them at feeding.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Wine Red Betta⚠️ With cautionAggressive · 5 cm · Medium care · 24–28 °C (75–82 °F)
- Wine Red Betta is aggressive and may chase or nip the smaller Cochu's Blue Tetra — plant heavily and break up sight lines.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Alligator Gar⛔ Not recommendedAggressive · 250 cm · Hard care · 24–28 °C (75–82 °F)
- Cochu's Blue Tetra is bite-sized to a 250 cm predatory alligator gar — it will be eaten.
- Alligator Gar is aggressive and may chase or nip the smaller Cochu's Blue Tetra — plant heavily and break up sight lines.
- Your 75 L tank is below the ~3785 L this pairing really wants — crowding raises aggression.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Clown Knifefish⛔ Not recommendedAggressive · 90 cm · Hard care · 24–28 °C (75–82 °F)
- Size gap is too large (90 vs 5 cm): Clown Knifefish will treat Cochu's Blue Tetra as food.
- Clown Knifefish clearly outsizes Cochu's Blue Tetra and is aggressive; risky unless the tank is big and well-planted.
- Your 75 L tank is below the ~750 L this pairing really wants — crowding raises aggression.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Fire Eel⛔ Not recommendedSemi-aggressive · 100 cm · Medium care · 24–28 °C (75–82 °F)
- Cochu's Blue Tetra is bite-sized to a 100 cm predatory fire eel — it will be eaten.
- Fire Eel clearly outsizes Cochu's Blue Tetra and is semi-aggressive; risky unless the tank is big and well-planted.
- Your 75 L tank is below the ~380 L this pairing really wants — crowding raises aggression.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Koi⛔ Not recommendedPeaceful · 90 cm · Medium care · 4–28 °C (39–82 °F)
- Koi (90 cm) is big enough to swallow the 5 cm Cochu's Blue Tetra whole.
- Your 75 L tank is below the ~3800 L this pairing really wants — crowding raises aggression.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Redtail Catfish⛔ Not recommendedAggressive · 120 cm · Hard care · 24–27 °C (75–81 °F)
- Size gap is too large (120 vs 5 cm): Redtail Catfish will treat Cochu's Blue Tetra as food.
- Expect Redtail Catfish to harass Cochu's Blue Tetra at times; give dense cover and watch them at feeding.
- Your 75 L tank is below the ~5700 L this pairing really wants — crowding raises aggression.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Spotted Gar⛔ Not recommendedAggressive · 90 cm · Hard care · 18–26 °C (64–79 °F)
- Size gap is too large (90 vs 5 cm): Spotted Gar will treat Cochu's Blue Tetra as food.
- Spotted Gar clearly outsizes Cochu's Blue Tetra and is aggressive; risky unless the tank is big and well-planted.
- Your 75 L tank is below the ~600 L this pairing really wants — crowding raises aggression.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Wels Catfish⛔ Not recommendedAggressive · 300 cm · Hard care · 15–25 °C (59–77 °F)
- Wels Catfish (300 cm) is big enough to swallow the 5 cm Cochu's Blue Tetra whole.
- Wels Catfish is aggressive and may chase or nip the smaller Cochu's Blue Tetra — plant heavily and break up sight lines.
- Your 75 L tank is below the ~20000 L this pairing really wants — crowding raises aggression.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Wolf Cichlid⛔ Not recommendedAggressive · 72 cm · Hard care · 24–30 °C (75–86 °F)
- Size gap is too large (72 vs 5 cm): Wolf Cichlid will treat Cochu's Blue Tetra as food.
- Wolf Cichlid is aggressive and may chase or nip the smaller Cochu's Blue Tetra — plant heavily and break up sight lines.
- Your 75 L tank is below the ~760 L this pairing really wants — crowding raises aggression.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
Compatibility is computed from each species' care data — a strong starting point, not a guarantee. Individual temperament varies, so always introduce new fish slowly and watch them.
Cochu's Blue Tetra care specs
- Care level
- Medium
- Breeding
- Hard
- Max size
- 5 cm (2 in)
- Min tank size
- 60 L (15.9 gal)
- Temperature
- 22–28 °C (72–82 °F)
- pH
- 5.5–7.5
- Hardness
- 2–12 dGH
- Lifespan
- 3–5 years
- Diet
- Omnivore
- Swim level
- Middle
- Group size
- 8+ (shoaling)
- Family
- Characidae
- Origin
- South America — Amazon basin, Peru and Colombia
What is a Cochu’s Blue Tetra?
Cochu’s Blue Tetra (Boehlkea fredcochui), also sold as the Blue King Tetra or Fredcochui Tetra, is a compact Amazonian characid that tops out at around 5 cm (2 in). Its claim to fame is an intense steel-blue iridescence that runs the full length of its body, shifting from royal blue to violet-silver depending on the angle of light — a quality that puts it firmly in the same visual league as neon and cardinal tetras. The belly carries a warm, translucent pinkish-orange tone that complements the blue particularly well under soft, warm aquarium lighting.
Despite its striking appearance, this species is less commonly stocked than the neon tetra and tends to be found at specialist shops rather than chain stores. It is a genuine Amazonian fish with soft-water requirements that must be taken seriously; it will not thrive long-term in hard, alkaline tap water. For the keeper willing to meet its chemistry needs, however, a school of Cochu’s Blue Tetras in a well-planted biotope tank is one of the most visually rewarding displays in the freshwater hobby.
Where do Cochu’s Blue Tetras come from naturally?
Wild populations are distributed across the Amazon basin, with the core range centred in Peru and Colombia. Like most Amazonian characids, they inhabit slow-moving forest streams, flooded clearings, and blackwater tributaries characterised by very soft, acidic water, heavy tannin staining from submerged leaf litter, and dense riparian vegetation. The water in these habitats is often dark amber in colour, with pH values that can drop well below 6.0 and hardness near zero.
Understanding this origin is the key to good husbandry. These fish evolved in an environment where bright overhead light rarely penetrates, flow is minimal, and the chemistry is extreme by general fishkeeping standards. Replicate those conditions — soft, gently acidic water, low light, slow flow, and organic décor — and the fish reward the effort with full colour and relaxed behaviour.
What size tank do Cochu’s Blue Tetras need?
The practical minimum is 60 litres (16 gallons) for a school of eight, which is the minimum group size for this species to feel secure and display properly. A longer, shallower footprint is preferable to a tall tank, because these fish are active mid-water swimmers and benefit from lateral swimming room more than depth.
Aim for a biotope-style setup: a dark substrate such as fine black sand or river sand, driftwood branches, a scattering of dried Indian almond or oak leaves, and clumps of fine-leaved plants like java fern, hornwort, or Amazon sword. Floating plants are particularly useful — they diffuse light naturally, reduce surface turbulence, and mimic the overhead canopy of the fish’s native habitat. Keep filtration gentle; a sponge filter or spray-bar return set to create minimal current suits these tetras far better than a powerful powerhead.
What water parameters do Cochu’s Blue Tetras need?
- Temperature: 22–28 °C (72–82 °F). They tolerate the lower end of this range better than many Amazonian tetras, but 24–26 °C (75–79 °F) is the comfort zone.
- pH: 5.5–7.5, with 6.0–7.0 as the practical sweet spot for colour and long-term health.
- Hardness: 2–12 dGH; soft water is strongly preferred.
If your tap water is hard or alkaline, consider using RO water blended with tap, peat filtration, or alder cones and Indian almond leaves to bring hardness and pH into range. The colour of this species is directly tied to water chemistry: fish in hard, alkaline water look washed out and stressed regardless of how good the rest of their care is. Test your water before buying, and cycle the tank fully before adding fish.
What do Cochu’s Blue Tetras eat?
Cochu’s Blue Tetras are omnivores with a healthy appetite. In the wild they consume small invertebrates, insect larvae, zooplankton, and plant material. In the aquarium they accept a wide range of foods readily:
- Staple: High-quality small-granule or micro-pellet tropical food forms the base of the diet.
- Variety: Frozen or live foods — daphnia, baby brine shrimp, micro-worms, and bloodworms — improve condition, intensify colour, and are essential for conditioning breeding fish.
- Supplement: A quality micro-flake or finely crushed flake rounds out the omnivore requirement.
Feed small amounts once or twice daily, offering only what they consume in two to three minutes. Their mouths are small, so food size matters — large pellets will be ignored. Skip a feeding day each week to prevent overfeeding and keep the water clean.
Are Cochu’s Blue Tetras peaceful — and what fish can live with them?
Cochu’s Blue Tetras are peaceful schooling fish with no significant aggression toward tank-mates of similar size. They spend most of their time in the middle zone of the water column, swimming actively in a loose school. The most important compatibility rule is that they must be kept in a group of at least eight — smaller groups produce skittish, pale fish prone to hiding.
They pair beautifully with other soft-water South American species: neon tetras, cardinal tetras, rummy-nose tetras, pencilfish, dwarf corydoras, and small loricariid catfish all share compatible requirements. Avoid boisterous or nippy species such as tiger barbs or large cichlids, and avoid fish with very different water-chemistry requirements such as African cichlids or livebearers from hard-water regions.
For a complete, filterable list of species that work — and which to avoid — see Cochu’s Blue Tetra tank mates.
How do you tell male and female Cochu’s Blue Tetras apart?
Sexual dimorphism in this species is subtle but visible to an attentive eye. Males are slightly slimmer in body profile and tend to show more intense, saturated iridescent blue coloration — especially when in spawning condition or competing for female attention. Females are a little fuller-bodied, most noticeably when gravid and carrying eggs, when the abdomen becomes visibly rounder. The colour difference is modest outside of peak condition, so the body-depth comparison is the more reliable indicator at most times. As with many tetras, gender distinction is easiest when a group is well-fed, in excellent water, and approaching breeding condition.
How do you breed Cochu’s Blue Tetras?
Breeding is rated hard and is not recommended as a first breeding project. The obstacles are typical of soft-water Amazonian tetras: narrow water-chemistry requirements, egg sensitivity, and small fry that need appropriately tiny first foods.
A dedicated breeding tank of around 20–40 L (5–10 gal) with near-zero hardness (RO or very soft water), pH 6.0–6.5, dim light, and spawning mops or fine-leaved plants is needed. Condition a pair or small group heavily on live and frozen foods for one to two weeks before introducing them to the breeding tank. Spawning is typically a scatter-and-abandon process: the pair spreads small adhesive eggs among plants. Remove adults promptly after spawning to prevent egg predation.
Eggs hatch in around 24–36 hours; fry are free-swimming within three to four days and initially require infusoria or commercial fry foods of appropriate particle size, graduating to baby brine shrimp as they grow. Water quality must be immaculate throughout, as the fry are fragile. Success rates improve considerably with experience and with access to reliably soft, acidic water.
What diseases are common in Cochu’s Blue Tetras?
Like most small tetras, Cochu’s Blue Tetras are most vulnerable when water quality or chemistry drifts from their requirements. The most common issues include:
- Ich (white spot): Classic white pinhead spots, usually triggered by chilling or sudden temperature swings. Prevention: stable temperature, avoid draughts near the tank.
- Velvet: A fine, dusty golden or rust-coloured sheen caused by Oodinium parasites. Often associated with new fish introductions. Prevention: quarantine all new arrivals for at least two weeks before adding to the main tank.
- Fin rot: Fraying or discolouring fins, almost always a consequence of poor water quality or a bacterial secondary infection after fin nipping. Prevention: consistent water changes and compatible tank-mates.
- Neon tetra disease: A microsporidian infection that causes fading patches along the body, for which there is no effective treatment. Prevention: source fish from reputable suppliers and quarantine before introduction.
Health note: disease diagnosis and medication dosing are beyond the scope of a care profile. For a sick fish, confirm the symptoms against a reputable veterinary or fish-health reference before treating. Always address water quality first — most tetra health problems are rooted there.
How long do Cochu’s Blue Tetras live?
In a well-maintained soft-water aquarium, Cochu’s Blue Tetras live 3–5 years. The lower end of that range is more common in tanks where water chemistry is suboptimal or the fish are kept in groups too small to reduce chronic stress. Fish kept in groups of eight or more, in soft acidic water with regular feeding variety and weekly water changes, reliably reach the upper end of the range. As with most tetras, they are typically sold as young adults, so the clock is already ticking by the time they reach your tank — the quality of your setup determines how much of their potential lifespan you see.
Frequently asked questions
Why does my Cochu's Blue Tetra look dull and not blue?
The vivid iridescent blue colour is strongly influenced by water chemistry, lighting angle, and stress level. Fish kept in hard or alkaline water, under harsh lighting, or in small groups quickly lose their sheen. Soft, slightly acidic water (pH 6.0–7.0), dim or plant-filtered light, and a school of at least eight are the main levers for unlocking full colour.
Can Cochu's Blue Tetras live with neon tetras or cardinal tetras?
Yes — they share almost identical water-chemistry requirements and a compatible peaceful temperament, making neons, cardinals and Cochu's blue tetras natural tank-mates in a soft-water South American biotope setup.
What you need to keep a cochu's blue tetra
The baseline is a heated, filtered 60 L+ tank: a reliable heater to hold 22–28 °C (72–82 °F), a gentle filter that won't batter a cochu's blue tetra in the current, and a tight-fitting lid. Cycle the tank fully before adding any fish.
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