Photo: VGW2006 at en.wikipedia (Public domain) — via Wikimedia Commons
Bloodfin Tetra (Aphyocharax anisitsi)
A gleaming silver torpedo with vivid red fins that tolerates cooler water and schools tirelessly from dusk to dawn.
Will it live with a Bloodfin Tetra?
We compare each fish against your bloodfin 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 Bloodfin Tetra in a shoal of 6+ 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)
- Both are peaceful, and their water overlaps around 22–28 °C — no size, zone or temperament conflicts.
- Keep Bloodfin Tetra in a shoal of 6+ 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)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Bloodfin Tetra in a shoal of 6+ 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; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Bloodfin Tetra in a shoal of 6+ 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)
- 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 Bloodfin Tetra in a shoal of 6+ 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)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- 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)
- Both are peaceful, and their water overlaps around 18–24 °C — no size, zone or temperament conflicts.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Diamond Tetra✅ CompatiblePeaceful · 6 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.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Bloodfin Tetra in a shoal of 6+ 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)
- Both are peaceful, and their water overlaps around 23–27 °C — no size, zone or temperament conflicts.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Keep Duplicareus Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Elegant Cory✅ CompatiblePeaceful · 6 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 Bloodfin Tetra in a shoal of 6+ 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 22–26 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Bloodfin Tetra in a shoal of 6+ 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)
- Both are peaceful, and their water overlaps around 27–28 °C — no size, zone or temperament conflicts.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Glass Bloodfin Tetra✅ CompatiblePeaceful · 6 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.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Keep Glass Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Guppy✅ CompatiblePeaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
- Both are peaceful, and their water overlaps around 22–28 °C — no size, zone or temperament conflicts.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Hillstream Loach✅ CompatiblePeaceful · 6 cm · Hard care · 20–24 °C (68–75 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Bloodfin Tetra 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)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Keep Narcissus II Cory in a shoal of 6+ or it gets stressed and nippy.
- Neon Dwarf Rainbowfish✅ CompatiblePeaceful · 6 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 Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Keep Neon Dwarf Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
- Panda Loach✅ CompatiblePeaceful · 6 cm · Hard care · 18–23 °C (64–73 °F)
- Both are peaceful, and their water overlaps around 18–23 °C — no size, zone or temperament conflicts.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Pearl Danio✅ CompatiblePeaceful · 6 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.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Keep Pearl Danio in a shoal of 6+ or it gets stressed and nippy.
- Platy✅ CompatiblePeaceful · 6 cm · Easy care · 21–28 °C (70–82 °F)
- Both are peaceful, and their water overlaps around 21–28 °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 Bloodfin Tetra 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)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Keep Rust Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Samurai Gourami✅ CompatiblePeaceful · 6 cm · Hard care · 24–28 °C (75–82 °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 Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Slate Corydoras✅ CompatiblePeaceful · 6 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.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Keep Slate Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Wine Red Betta✅ CompatibleAggressive · 5 cm · Medium care · 24–28 °C (75–82 °F)
- Peaceful + Aggressive, 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 Bloodfin Tetra 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)
- Adult Amano Shrimp might survive with Bloodfin Tetra, but expect the young to be eaten — plant heavily.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Ash Lipped Apisto⚠️ With cautionSemi-aggressive · 7 cm · Hard care · 24–29 °C (75–84 °F)
- Ash Lipped Apisto and Bloodfin Tetra are close in size, but the semi-aggressive one tends to dominate — add bloodfin 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 Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Betta⚠️ With cautionSemi-aggressive · 6.5 cm · Easy care · 24–28 °C (75–82 °F)
- Betta and Bloodfin Tetra are close in size, but the semi-aggressive one tends to dominate — add bloodfin tetra in a group to spread the pressure.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Black Ruby Barb⚠️ With cautionSemi-aggressive · 6 cm · Easy care · 22–26 °C (72–79 °F)
- Black Ruby Barb and Bloodfin Tetra are close in size, but the semi-aggressive one tends to dominate — add bloodfin tetra in a group to spread the pressure.
- Your 75 L tank is below the ~100 L this pairing really wants — crowding raises aggression.
- Keep Bloodfin Tetra in a shoal of 6+ 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)
- Expect Black Skirt Tetra to harass Bloodfin Tetra at times; give dense cover and watch them at feeding.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Keep Black Skirt Tetra in a shoal of 6+ or it gets stressed and nippy.
- Colombian Tetra⚠️ With cautionSemi-aggressive · 6.5 cm · Easy care · 24–28 °C (75–82 °F)
- Colombian Tetra and Bloodfin Tetra are close in size, but the semi-aggressive one tends to dominate — add bloodfin tetra in a group to spread the pressure.
- Your 75 L tank is below the ~114 L this pairing really wants — crowding raises aggression.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Keep Colombian 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 and Bloodfin Tetra are close in size, but the semi-aggressive one tends to dominate — add bloodfin tetra in a group to spread the pressure.
- Keep Bloodfin Tetra in a shoal of 6+ 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 Bloodfin Tetra in a shoal of 6+ 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)
- Eastern Betta is semi-aggressive and may chase or nip the smaller Bloodfin Tetra — plant heavily and break up sight lines.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- GloFish Tetra⚠️ With cautionSemi-aggressive · 6 cm · Easy care · 21–28 °C (70–82 °F)
- GloFish Tetra and Bloodfin Tetra are close in size, but the semi-aggressive one tends to dominate — add bloodfin tetra in a group to spread the pressure.
- Keep Bloodfin Tetra in a shoal of 6+ 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)
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Bloodfin Tetra in a shoal of 6+ 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 Bloodfin Tetra in a shoal of 6+ 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)
- Expect Odessa Barb to harass Bloodfin Tetra at times; give dense cover and watch them at feeding.
- Keep Bloodfin Tetra in a shoal of 6+ 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)
- Peaceful Betta is semi-aggressive and may chase or nip the smaller Bloodfin Tetra — plant heavily and break up sight lines.
- Keep Bloodfin 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)
- Smaragd Betta is aggressive and may chase or nip the smaller Bloodfin Tetra — plant heavily and break up sight lines.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Three-striped Dwarf Cichlid⚠️ With cautionSemi-aggressive · 6 cm · Medium care · 23–29 °C (73–84 °F)
- Three-striped Dwarf Cichlid and Bloodfin Tetra are close in size, but the semi-aggressive one tends to dominate — add bloodfin tetra in a group to spread the pressure.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Alligator Gar⛔ Not recommendedAggressive · 250 cm · Hard care · 24–28 °C (75–82 °F)
- Bloodfin Tetra is bite-sized to a 250 cm predatory alligator gar — it will be eaten.
- Expect Alligator Gar to harass Bloodfin Tetra at times; give dense cover and watch them at feeding.
- Your 75 L tank is below the ~3785 L this pairing really wants — crowding raises aggression.
- Keep Bloodfin Tetra in a shoal of 6+ 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 5.5 cm): Clown Knifefish will treat Bloodfin Tetra as food.
- Clown Knifefish is aggressive and may chase or nip the smaller Bloodfin Tetra — plant heavily and break up sight lines.
- Your 75 L tank is below the ~750 L this pairing really wants — crowding raises aggression.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Fire Eel⛔ Not recommendedSemi-aggressive · 100 cm · Medium care · 24–28 °C (75–82 °F)
- Bloodfin Tetra is bite-sized to a 100 cm predatory fire eel — it will be eaten.
- Fire Eel clearly outsizes Bloodfin 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 Bloodfin Tetra in a shoal of 6+ 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 5.5 cm Bloodfin Tetra whole.
- Your 75 L tank is below the ~3800 L this pairing really wants — crowding raises aggression.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Redtail Catfish⛔ Not recommendedAggressive · 120 cm · Hard care · 24–27 °C (75–81 °F)
- Redtail Catfish (120 cm) is big enough to swallow the 5.5 cm Bloodfin Tetra whole.
- Redtail Catfish is aggressive and may chase or nip the smaller Bloodfin Tetra — plant heavily and break up sight lines.
- Your 75 L tank is below the ~5700 L this pairing really wants — crowding raises aggression.
- Keep Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
- Spotted Gar⛔ Not recommendedAggressive · 90 cm · Hard care · 18–26 °C (64–79 °F)
- Spotted Gar (90 cm) is big enough to swallow the 5.5 cm Bloodfin Tetra whole.
- Expect Spotted Gar to harass Bloodfin Tetra at times; give dense cover and watch them at feeding.
- Your 75 L tank is below the ~600 L this pairing really wants — crowding raises aggression.
- Keep Bloodfin Tetra in a shoal of 6+ 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 5.5 cm Bloodfin Tetra whole.
- Expect Wels Catfish to harass Bloodfin Tetra at times; give dense cover and watch them at feeding.
- Your 75 L tank is below the ~20000 L this pairing really wants — crowding raises aggression.
- Keep Bloodfin Tetra in a shoal of 6+ 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 5.5 cm): Wolf Cichlid will treat Bloodfin Tetra as food.
- Wolf Cichlid clearly outsizes Bloodfin Tetra and is aggressive; risky unless the tank is big and well-planted.
- Your 75 L tank is below the ~760 L this pairing really wants — crowding raises aggression.
- Keep Bloodfin Tetra in a shoal of 6+ 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.
Bloodfin Tetra care specs
- Care level
- Easy
- Breeding
- Easy
- Max size
- 5.5 cm (2.2 in)
- Min tank size
- 40 L (10.6 gal)
- Temperature
- 18–28 °C (64–82 °F)
- pH
- 6–7.8
- Hardness
- 3–12 dGH
- Lifespan
- 5–10 years
- Diet
- Omnivore
- Swim level
- Middle
- Group size
- 6+ (shoaling)
- Family
- Characidae
- Origin
- South America — Paraná River basin, Argentina and Paraguay
What is a Bloodfin Tetra?
The bloodfin tetra (Aphyocharax anisitsi) is a small, streamlined characid from the cool river systems of southern South America. The common name is instantly self-explanatory: the body is a bright, reflective silver while the dorsal, adipose, caudal and anal fins blaze a deep, arterial red — a combination that looks striking under aquarium lighting and remains bold even in a busy community tank.
Reaching around 5.5 cm (about 2.2 in), bloodfins are compact but energetic. They spend almost all their time in the middle of the water column, rarely venturing to the surface or rooting around the substrate, which makes them excellent partners for bottom-dwellers and surface-oriented species alike. Their care level is genuinely easy — they accept a wide band of water parameters, eat almost anything offered, and are reliably peaceful — yet the payoff in terms of visual impact and natural behaviour is high.
Where do Bloodfin Tetras come from?
Bloodfin tetras are native to the Paraná River basin in Argentina and Paraguay. This is a large, well-oxygenated river system with clear to slightly turbid water, and conditions that lean cooler than those found in the tropical regions associated with most hobby tetras. Water in their native range tends to be soft to moderately hard and mildly acidic to near-neutral, flowing steadily over sandy or gravelly substrates edged with riparian vegetation.
The cooler end of this natural origin is what sets the bloodfin apart from the majority of characids — it is genuinely adapted to water temperatures that would stress or kill many other tetras. Understanding this origin also explains their preference for open midwater swimming space and subdued, dappled light that penetrates through overhanging vegetation.
What size tank does a Bloodfin Tetra need?
The minimum practical tank size for a school of bloodfin tetras is 40 litres (about 10 gallons), but this is tight — it suits a group of six in a well-maintained, lightly stocked tank. For the bolder, more natural display that a larger school delivers, a 60–80 L (16–21 gal) tank is a more comfortable target.
Because bloodfins are active midwater swimmers, tank footprint matters more than height. A longer, shallower tank gives the fish room to form a proper shoaling column and turn at pace without constantly running out of space. Aim for a tank at least 60 cm (24 in) long for any meaningful group.
Decor should include open midwater swimming lanes flanked by planting at the sides and back — fine-leaved plants such as Vallisneria or Hornwort work well and echo the riverine vegetation of their home waters. A secure-fitting lid is advisable; bloodfins are capable jumpers when startled.
What water parameters do Bloodfin Tetras need?
Bloodfins have an unusually broad tolerance range for a tetra:
- Temperature: 18–28 °C (64–82 °F). Most community setups at 22–26 °C (72–79 °F) are ideal. They are one of very few tetras that work in unheated tanks in temperate rooms.
- pH: 6.0–7.8 — soft and acidic through to slightly alkaline.
- Hardness: 3–12 dGH, soft to moderately hard.
Stability is more important than chasing the exact midpoint. Rapid temperature swings — even within their stated range — will stress a school far more than water that sits steadily at either end. As with all tetras, ensure the tank is fully cycled before adding fish, and keep up with weekly partial water changes to hold nitrates in check.
What do Bloodfin Tetras eat?
Bloodfin tetras are omnivores with small mouths and opportunistic appetites. In the wild they pick off zooplankton, insect larvae and plant matter from the mid-column. In captivity they accept virtually all standard aquarium foods without fuss.
A good rotation looks like this:
- Staple: Quality small flake or micro-pellet, offered twice daily in amounts consumed within two minutes.
- Several times a week: Frozen or live daphnia, brine shrimp, bloodworms or micro-worms to support colour and conditioning.
- Occasional: Blanched spinach or spirulina flake to round out the plant component of their omnivorous diet.
Feed small portions and remove uneaten food promptly. In a busy community tank, ensure quieter tank-mates also reach the food — bloodfins are quick but not aggressive feeders, so this is rarely a problem with other similarly sized fish.
Are Bloodfin Tetras aggressive — and what fish can live with them?
Bloodfin tetras are peaceful community fish and one of the safest choices for a mixed-species setup. They do not bother tank-mates, do not claim territories, and their small mouths mean they are no threat to anything roughly their own size or larger. The only nuance worth noting is a mild tendency to nip very long, slow-moving fins — particularly in an underschooled group. Keep them in a group of six or more to direct shoaling energy inward rather than outward.
Ideal tank-mates are similarly sized peaceful species that share their midwater zone or occupy a different level: corydoras and other small catfish on the bottom, harlequin rasboras or ember tetras in the midwater alongside them, and peaceful small gouramis or danios at the top. Avoid large, predatory fish that will treat a 5.5 cm tetra as a snack.
For a detailed, filterable list of pairings that work — and those that don’t — see Bloodfin Tetra tank mates.
How do you tell male and female Bloodfin Tetras apart?
Adult bloodfins are sexually dimorphic, though the differences are subtle compared to more dramatically different species. Females are noticeably plumper in the body, particularly when gravid with eggs — a well-fed, mature female in spawning condition looks distinctly rounder than her tank-mates. Males tend to display slightly more intensely coloured red fins, and crucially, sexually mature males develop small hooks on the anal fin — a feature that is unique to mature males and makes definitive sexing straightforward once you know what to look for. These hooks sometimes cause males to become momentarily tangled in fine-mesh nets during handling.
How do Bloodfin Tetras breed?
Bloodfins are classified as easy to breed, and they will often spawn in a mature, well-planted community tank without deliberate intervention. Spawning is egg-scattering: the pair or group broadcasts adhesive eggs over fine-leaved plants or into open water, then promptly ignore — and often eat — the eggs.
For deliberate breeding, set up a small dedicated tank (around 20–30 L) with very soft, slightly acidic water, dim light, and a dense mat of fine-leaved plants or a spawning mop. Condition a group of adults on live and frozen foods, then introduce a small group or a selected pair. Spawning typically occurs in the morning. Remove adults immediately after spawning to prevent egg predation. The eggs hatch in 24–36 hours at around 24 °C (75 °F), and fry are free-swimming within a few more days. First foods are infusoria or commercial liquid fry foods, transitioning to baby brine shrimp nauplii as they grow.
What are common Bloodfin Tetra diseases?
Bloodfins are a robust species and rarely present serious disease problems in a well-maintained tank. The most common issues are:
- Ich (white spot): White granular spots across the body and fins, typically triggered by temperature swings or the stress of a new tank. Prevention centres on stable water temperature and proper quarantine of new arrivals.
- Fin rot: Ragged, disintegrating fin edges almost always linked to poor water quality or bacterial infection following physical damage. Weekly water changes and avoiding fin-nipping tank-mates are the primary preventative steps.
- Velvet (Oodinium): A fine gold or rust-coloured dusting on the skin, particularly visible under a torch at an angle. Often introduced with new fish; quarantine is the best prevention.
- Internal parasites: Occasional wasting or unusual faeces, most often brought in with wild-caught stock or live foods. Quarantine new fish and source live foods carefully.
The single most effective disease-prevention protocol is straightforward: a cycled, stable tank, regular water changes, and a minimum four-week quarantine for all new arrivals before they join the main display.
Health note: symptoms of many fish diseases overlap significantly, and medication choices and dosing depend on the specific pathogen involved. Confirm a diagnosis against a reputable veterinary or fish-health source before treating.
How long do Bloodfin Tetras live?
Given good care, bloodfin tetras live 5–10 years — an impressive span for a small tetra and one of the reasons experienced keepers hold them in high regard. The keys are consistent water quality, an appropriate group size (six or more), a varied diet, and stable temperatures within their comfort range. Fish kept in cold, cramped or nutritionally poor conditions rarely approach that upper figure; fish in a well-run planted community tank regularly exceed five years and often reach the top of the range.
Frequently asked questions
Can bloodfin tetras live in an unheated tank?
Yes — they are one of the few tetras that genuinely tolerate cooler water, down to around 18 °C. That makes them useful for unheated setups in temperate rooms, though sustained temperatures below 16 °C or rapid swings will stress them. Most community tanks at 22–26 °C suit them perfectly.
How many bloodfin tetras should I keep together?
Keep at least six, and ideally ten or more. A larger school produces a much bolder, more active display — isolated fish become timid and are more prone to fin-nipping. A group of eight to twelve in a well-planted 60–80 L tank is a sweet spot for most keepers.
What you need to keep a bloodfin tetra
The baseline is a heated, filtered 40 L+ tank: a reliable heater to hold 18–28 °C (64–82 °F), a gentle filter that won't batter a bloodfin tetra in the current, and a tight-fitting lid. Cycle the tank fully before adding any fish.
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