Humpbacked Tetra (Heterocharax macrolepis)
A strikingly unusual Amazonian predator with an arched back, oversized fangs and a strong schooling instinct — a specialist gem for biotope tanks.
Will it live with a Humpbacked Tetra?
We compare each fish against your humpbacked 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)
- Compatible on the things that matter: shared water near 24–26 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Humpbacked 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.
- Agassiz's Corydoras✅ CompatiblePeaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
- Compatible on the things that matter: shared water near 24–28 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Agassiz's Corydoras 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 24–28 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Humpbacked 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)
- Semi-aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Humpbacked 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.
- Blackline Rasbora✅ CompatiblePeaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
- Semi-aggressive + Peaceful, but with no direct clash here; 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 Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Blackline Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Blood Red Tiger Pleco✅ CompatiblePeaceful · 6 cm · Medium care · 24–29 °C (75–84 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 24–28 °C — no size, zone or temperament conflicts.
- Keep Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Bloodfin Tetra✅ CompatiblePeaceful · 5.5 cm · Easy care · 18–28 °C (64–82 °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 Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Butterfly Hillstream Loach✅ CompatiblePeaceful · 6 cm · Hard care · 18–24 °C (64–75 °F)
- Compatible on the things that matter: shared water near 24–24 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Diamond Tetra✅ CompatiblePeaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, 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 Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Diamond Tetra in a shoal of 6+ or it gets stressed and nippy.
- Duplicareus Corydoras✅ CompatiblePeaceful · 5.5 cm · Medium care · 23–27 °C (73–81 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 24–27 °C — no size, zone or temperament conflicts.
- Keep Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Duplicareus Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Dwarf Chain Loach✅ CompatiblePeaceful · 6 cm · Medium care · 24–29 °C (75–84 °F)
- Semi-aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Humpbacked 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.
- Elegant Cory✅ CompatiblePeaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
- Compatible on the things that matter: shared water near 24–28 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Elegant Cory in a shoal of 6+ or it gets stressed and nippy.
- False Julii Corydoras✅ CompatiblePeaceful · 6 cm · Easy care · 22–26 °C (72–79 °F)
- Compatible on the things that matter: shared water near 24–26 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep False Julii Corydoras in a shoal of 6+ or it gets stressed and nippy.
- German Blue Ram✅ CompatiblePeaceful · 6 cm · Hard care · 27–30 °C (81–86 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 27–28 °C — no size, zone or temperament conflicts.
- Keep Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Glass Bloodfin Tetra✅ CompatiblePeaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
- Semi-aggressive + Peaceful, but with no direct clash here; 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 Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Glass Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Horseman Cory✅ CompatiblePeaceful · 5 cm · Medium care · 22–26 °C (72–79 °F)
- Semi-aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Humpbacked 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)
- Semi-aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Humpbacked 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)
- Compatible on the things that matter: shared water near 24–26 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Humpbacked 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)
- Semi-aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Humpbacked 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.
- Morse Code Corydoras✅ CompatiblePeaceful · 5 cm · Medium care · 23–26 °C (73–79 °F)
- Semi-aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Humpbacked 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.
- Narcissus II Cory✅ CompatiblePeaceful · 5.5 cm · Medium care · 22–26 °C (72–79 °F)
- Semi-aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Narcissus II Cory in a shoal of 6+ or it gets stressed and nippy.
- Panda Corydoras✅ CompatiblePeaceful · 5 cm · Medium care · 20–26 °C (68–79 °F)
- Semi-aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Humpbacked 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.
- Rust Corydoras✅ CompatiblePeaceful · 5.5 cm · Easy care · 23–27 °C (73–81 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 24–27 °C — no size, zone or temperament conflicts.
- Keep Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Rust Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Skunk Corydoras✅ CompatiblePeaceful · 5 cm · Easy care · 22–26 °C (72–79 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 24–26 °C — no size, zone or temperament conflicts.
- Keep Humpbacked 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.
- Amano Shrimp⚠️ With cautionPeaceful · 5 cm · Easy care · 18–28 °C (64–82 °F)
- Humpbacked Tetra may eat Amano Shrimp or pick off its shrimplets — a densely planted tank with moss gives them a fighting chance.
- Keep Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Blue Turbo Snail⚠️ With cautionPeaceful · 5 cm · Medium care · 25–30 °C (77–86 °F)
- Different pH ranges (5.5–7.2 vs 7.5–8.5); doable if you sit in the shared band, but not ideal long-term.
- Keep Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Checkered Barb⚠️ With cautionPeaceful · 5 cm · Easy care · 20–25 °C (68–77 °F)
- Expect Humpbacked Tetra to harass Checkered Barb at times; give dense cover and watch them at feeding.
- Keep Humpbacked 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⚠️ With cautionPeaceful · 5 cm · Easy care · 23–27 °C (73–81 °F)
- Humpbacked Tetra and Cherry Barb are close in size, but the semi-aggressive one tends to dominate — add cherry barb in a group to spread the pressure.
- Keep Humpbacked 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⚠️ With cautionPeaceful · 5 cm · Hard care · 25–30 °C (77–86 °F)
- Expect Humpbacked Tetra to harass Chocolate Gourami at times; give dense cover and watch them at feeding.
- Keep Humpbacked 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.
- Cochu's Blue Tetra⚠️ With cautionPeaceful · 5 cm · Medium care · 22–28 °C (72–82 °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.
- Keep Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Cochu's Blue Tetra in a shoal of 8+ or it gets stressed and nippy.
- Firehead Tetra⚠️ With cautionPeaceful · 5 cm · Medium care · 24–28 °C (75–82 °F)
- Humpbacked Tetra and Firehead Tetra are close in size, but the semi-aggressive one tends to dominate — add firehead tetra in a group to spread the pressure.
- Keep Humpbacked 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⚠️ With cautionPeaceful · 5 cm · Easy care · 23–27 °C (73–81 °F)
- Humpbacked Tetra is semi-aggressive and may chase or nip the smaller Five-banded Barb — plant heavily and break up sight lines.
- Keep Humpbacked 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⚠️ With cautionPeaceful · 5 cm · Easy care · 22–28 °C (72–82 °F)
- Humpbacked Tetra and Forktail Blue-eye are close in size, but the semi-aggressive one tends to dominate — add forktail blue-eye in a group to spread the pressure.
- Keep Humpbacked 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⚠️ With cautionPeaceful · 5 cm · Medium care · 23–28 °C (73–82 °F)
- Expect Humpbacked Tetra to harass Half-striped Penguin Tetra at times; give dense cover and watch them at feeding.
- Keep Humpbacked 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⚠️ With cautionPeaceful · 5 cm · Easy care · 23–28 °C (73–82 °F)
- Humpbacked Tetra is semi-aggressive and may chase or nip the smaller Harlequin Rasbora — plant heavily and break up sight lines.
- Keep Humpbacked 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⚠️ With cautionPeaceful · 5 cm · Easy care · 22–28 °C (72–82 °F)
- Expect Humpbacked Tetra to harass Honey Gourami at times; give dense cover and watch them at feeding.
- Keep Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Mystery Snail⚠️ With cautionPeaceful · 5 cm · Easy care · 20–28 °C (68–82 °F)
- Humpbacked Tetra is semi-aggressive and may chase or nip the smaller Mystery Snail — plant heavily and break up sight lines.
- Keep Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Rummy-nose Tetra⚠️ With cautionPeaceful · 5 cm · Medium care · 23–29 °C (73–84 °F)
- Expect Humpbacked Tetra to harass Rummy-nose Tetra at times; give dense cover and watch them at feeding.
- Keep Humpbacked 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.
- Silvertip Tetra⚠️ With cautionSemi-aggressive · 5 cm · Easy care · 22–28 °C (72–82 °F)
- Both are a bit pushy (semi-aggressive + semi-aggressive) — workable only in a larger tank with cover and broken sight lines.
- Keep Humpbacked 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.
- Spotfin Betta⚠️ With cautionSemi-aggressive · 5 cm · Medium care · 23–28 °C (73–82 °F)
- Humpbacked Tetra and Spotfin Betta can both be territorial; doable with space and dense planting, but watch for chasing.
- Keep Humpbacked 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)
- Two assertive fish, one genuinely aggressive: Humpbacked Tetra and Alligator Gar will hold territory and clash.
- Alligator Gar (250 cm) is big enough to swallow the 5 cm Humpbacked Tetra whole.
- Alligator Gar is slow and long-finned; a busy humpbacked tetra shoal tends to nip at it. Keep humpbacked tetra in a proper group of 8+ and watch them closely.
- Your 80 L tank is below the ~3785 L this pairing really wants — crowding raises aggression.
- Keep Humpbacked 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)
- Humpbacked Tetra and Clown Knifefish are both territorial and at least one is outright aggressive — expect serious fighting.
- Humpbacked Tetra is bite-sized to a 90 cm predatory clown knifefish — it will be eaten.
- Your 80 L tank is below the ~750 L this pairing really wants — crowding raises aggression.
- Keep Humpbacked 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)
- Size gap is too large (100 vs 5 cm): Fire Eel will treat Humpbacked Tetra as food.
- Both are a bit pushy (semi-aggressive + semi-aggressive) — workable only in a larger tank with cover and broken sight lines.
- Your 80 L tank is below the ~380 L this pairing really wants — crowding raises aggression.
- Keep Humpbacked 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)
- Humpbacked Tetra is bite-sized to a 90 cm koi — it will be eaten.
- Humpbacked Tetra is a notorious fin-nipper — even though Koi is larger, an active shoal will harass its trailing fins. Only safe in a full group of 8+ with plenty of cover.
- Your 80 L tank is below the ~3800 L this pairing really wants — crowding raises aggression.
- Keep Humpbacked 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)
- Two assertive fish, one genuinely aggressive: Humpbacked Tetra and Redtail Catfish will hold territory and clash.
- Humpbacked Tetra is bite-sized to a 120 cm predatory redtail catfish — it will be eaten.
- Your 80 L tank is below the ~5700 L this pairing really wants — crowding raises aggression.
- Keep Humpbacked 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)
- Two assertive fish, one genuinely aggressive: Humpbacked Tetra and Spotted Gar will hold territory and clash.
- Spotted Gar (90 cm) is big enough to swallow the 5 cm Humpbacked Tetra whole.
- Spotted Gar is slow and long-finned; a busy humpbacked tetra shoal tends to nip at it. Keep humpbacked tetra in a proper group of 8+ and watch them closely.
- Your 80 L tank is below the ~600 L this pairing really wants — crowding raises aggression.
- Keep Humpbacked 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)
- Two assertive fish, one genuinely aggressive: Humpbacked Tetra and Wels Catfish will hold territory and clash.
- Wels Catfish (300 cm) is big enough to swallow the 5 cm Humpbacked Tetra whole.
- Your 80 L tank is below the ~20000 L this pairing really wants — crowding raises aggression.
- Keep Humpbacked 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)
- Humpbacked Tetra and Wolf Cichlid are both territorial and at least one is outright aggressive — expect serious fighting.
- Humpbacked Tetra is bite-sized to a 72 cm predatory wolf cichlid — it will be eaten.
- Humpbacked Tetra is a notorious fin-nipper — even though Wolf Cichlid is larger, an active shoal will harass its trailing fins. Only safe in a full group of 8+ with plenty of cover.
- Your 80 L tank is below the ~760 L this pairing really wants — crowding raises aggression.
- Keep Humpbacked 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.
Humpbacked Tetra care specs
- Care level
- Hard
- Breeding
- Very Hard
- Max size
- 5 cm (2 in)
- Min tank size
- 80 L (21.1 gal)
- Temperature
- 24–28 °C (75–82 °F)
- pH
- 5.5–7.2
- Hardness
- 1–10 dGH
- Lifespan
- 3–5 years
- Diet
- Carnivore
- Swim level
- Middle
- Group size
- 8+ (shoaling)
- Family
- Characidae
- Origin
- South America — Amazon, Orinoco and Essequibo river basins (Brazil, Colombia, Ecuador, Guyana, Peru, Venezuela)
What is a Humpbacked Tetra?
The Humpbacked Tetra (Heterocharax macrolepis) is a small but formidable Amazonian characin that breaks every expectation of a 5 cm (2 in) tetra. Its most immediate feature is structural: a pronounced arch behind the head creates a distinctly humped dorsal profile unlike any common tetra on the market. Its second surprise is dental — enlarged, interlocking canine teeth it deploys to snatch scales and fin tissue from other fish, a feeding strategy called lepidophagy. In a well-designed aquarium a school of eight or more moving through amber-tinted, dimly lit water is genuinely striking: the silver body catches light with an iridescent blue-green sheen as the fish move in tight formation. This is firmly a species for experienced aquarists — it demands soft, acidic blackwater conditions, a carefully chosen species list and a keeper who understands its predatory nature. It circulates mainly through specialist importers and hobbyist clubs.
Where does the Humpbacked Tetra come from?
Heterocharax macrolepis is distributed across the Amazon, Orinoco and Essequibo river basins, spanning Brazil, Colombia, Ecuador, Guyana, Peru and Venezuela. It inhabits lowland tropical tributaries, igapó (flooded forest) and smaller blackwater streams, where leaf litter accumulates on dark substrate and tannins stain the water amber. The fish evolved in warm, soft, acidic, low-conductivity water with gentle currents and low light filtered through forest canopy. Replicating these conditions is the difference between a settled, feeding school and a stressed group that hides and refuses food.
What tank setup does the Humpbacked Tetra need?
An 80-litre (21-gallon) aquarium is the practical minimum for a school of eight — the smallest group that keeps this species behaviorally settled. Prefer a longer footprint over a tall one; this is a mid-water fish that uses open horizontal swimming lanes, and a tank 80–90 cm long gives the school room to move coherently.
Use dark, fine substrate — black sand is ideal — and add dried leaves (Indian almond, oak or beech) plus several pieces of driftwood for shade and natural tannin release. Floating plants such as Amazon frogbit diffuse overhead light and complete the blackwater feel. Filtration must be efficient but gentle: a sponge filter or low-flow canister prevents the turbulent current that disrupts schooling behaviour. Keep the tank covered — like most characins, they can jump.
What water parameters does the Humpbacked Tetra need?
- Temperature: 24–28 °C (75–82 °F). A reliable heater is non-negotiable.
- pH: 5.5–7.2; the species settles and colours best in the 6.0–6.8 range.
- Hardness: 1–10 dGH. Hard or alkaline tap water will suppress appetite and dull colouration. If your tap water is hard, blend RO water with dechlorinated tap to reach target parameters.
Stability matters as much as hitting exact numbers. Cycle the tank before adding fish, and keep up 20–25% weekly water changes. In a leaf-litter setup, monitor pH regularly — organic acids from botanicals can push it lower over time.
What do Humpbacked Tetras eat?
The Humpbacked Tetra is a carnivore whose wild diet centres on lepidophagy — taking scales and fin tissue from other fish. In aquaria, a menu of high-quality meaty foods meets their nutritional needs without requiring them to target tank-mates.
Offer small carnivore pellets as the staple, rotated with frozen or live bloodworms, daphnia, cyclops and brine shrimp. Live and frozen foods trigger active hunting behaviour and bring out the school’s best colour. Feed once or twice daily in amounts cleared within two to three minutes, and remove uneaten food promptly. Newly imported fish often refuse prepared foods initially — start with live or frozen items to establish feeding confidence, then introduce dried foods gradually alongside.
How does the Humpbacked Tetra behave, and what are its compatible tank mates?
The Humpbacked Tetra is semi-aggressive, and its behaviour is driven almost entirely by its predatory dentition. It will opportunistically bite fins and scales from tank-mates — not out of stress but as a genuine feeding strategy. The risk is highest with slow-moving, long-finned or small fish; nano species, fancy guppies, angelfish and anything with trailing fins are poor choices.
Within a school of eight or more the fish are cohesive and comparatively settled; intraspecific aggression is low when group size is adequate. A species-only biotope setup is the simplest and safest approach. Where mixed tanks are attempted, robust, fast-moving Amazonian species of similar or larger size — armoured substrate catfish, for instance — offer the best chance of a workable combination, but close monitoring is essential.
For a full compatibility list, see Humpbacked Tetra tank mates.
How do you tell male from female Humpbacked Tetras?
Sexual dimorphism in H. macrolepis is subtle. Both sexes share the characteristic dorsal hump, and colouration is similar in healthy individuals. The clearest indicator is body depth: females in breeding condition become noticeably fuller and more rounded in the belly, giving them a deeper profile when viewed from above or head-on, while males remain slimmer. Outside breeding condition, sexing individuals at a distance is unreliable. The most practical approach for would-be breeders is to purchase a group of at least eight and allow natural pairings to form.
Can the Humpbacked Tetra be bred in captivity?
Captive breeding is rated very hard and documented cases are rare. The species has occasionally spawned in home aquaria under conditions that closely mimic its natural environment, but raising fry to adulthood is a significant challenge.
Conditioning adults requires a varied, nutritionally rich live and frozen food diet over several weeks. Spawning is likely an egg-scattering event among fine-leaved plants or spawning mops, consistent with other Amazonian characins. Adults will predate eggs immediately, so separation is essential — either remove adults after spawning or use a fine-mesh egg-collection setup. Fry will be very small at hatching and require infusoria or paramecia before transitioning to larger foods. A dedicated spawning tank of 40–60 litres (10–16 gallons) with extremely soft, acidic water (pH 5.5–6.5, hardness under 4 dGH), dim lighting and conditioned adults is the recommended starting framework.
What diseases should Humpbacked Tetra keepers watch for?
This species has no unique susceptibility profile, but several conditions are worth monitoring:
- Ich (white spot): Triggered most often by temperature fluctuation or chilling. Prevention: a reliable thermostat and a four-week quarantine for all new fish.
- Velvet (Oodinium): Presents as fine golden or rusty dust on the body. Stress from incorrect water conditions suppresses immune response and increases susceptibility — maintaining soft, acidic parameters is the key preventive.
- Bacterial infections from fin damage: Given the species’ fin-biting habit, secondary bacterial infections at wound sites can develop quickly. Monitor the school regularly and address the root cause — incompatible tank-mates or an undersized group — before it becomes a water-quality problem.
- Internal parasites: Wild-caught imports frequently carry internal parasites. A minimum four-week quarantine before adding new fish to an established tank is standard practice for any wild-caught Amazonian species.
Health note: Disease identification, treatment selection and medication dosing are beyond the scope of a care profile. If fish appear sick, confirm symptoms against a reputable fish-health or veterinary resource before medicating. Correct water parameters and strict quarantine remain the most effective prevention tools.
How long does the Humpbacked Tetra live?
With consistent, appropriate care the Humpbacked Tetra lives 3–5 years in captivity. The upper end of that range is achievable when soft-acid water parameters are maintained, diet is varied and nutritious, and the stress of inappropriate tank-mates or incorrect conditions is avoided. Wild-caught imports may arrive as adults of unknown age, so sourcing healthy stock from a reputable specialist importer — and quarantining thoroughly before introduction — is the most important single step toward a long-lived, thriving school.
Frequently asked questions
Is the Humpbacked Tetra safe with other fish?
With caution. It uses its outsized fangs to bite chunks from the fins of similarly sized or smaller tank-mates, so it is best kept as a species-specific school or alongside robust, fast-moving fish too large to be harassed. Avoid slow-finned or nano species.
Why is it called the Humpbacked Tetra?
The species has a distinctly arched dorsal profile — a pronounced hump behind the head — that sets it apart visually from typical tetra body shapes. The large canine-like teeth give rise to the alternative name Fangtooth Tetra.
What you need to keep a humpbacked tetra
The baseline is a heated, filtered 80 L+ tank: a reliable heater to hold 24–28 °C (75–82 °F), a gentle filter that won't batter a humpbacked tetra in the current, and a tight-fitting lid. Cycle the tank fully before adding any fish.
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