Photo: Wikimedia Commons contributor (CC BY-SA 2.5) — via Wikimedia Commons
Diamond Tetra (Moenkhausia pittieri)
A living jewel: every scale throws off prismatic silver-violet flashes, and a shoal of six under a dimmed light is one of the most striking sights in the hobby.
Will it live with a Diamond Tetra?
We compare each fish against your diamond 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 22–26 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Diamond 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)
- Compatible on the things that matter: shared water near 22–28 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Diamond 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.
- Blackline Rasbora✅ CompatiblePeaceful · 6 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 Diamond 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)
- Compatible on the things that matter: shared water near 24–28 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Diamond Tetra in a shoal of 6+ or it gets stressed and nippy.
- Bloodfin Tetra✅ CompatiblePeaceful · 5.5 cm · Easy care · 18–28 °C (64–82 °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 Diamond Tetra in a shoal of 6+ 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 22–24 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Diamond Tetra in a shoal of 6+ or it gets stressed and nippy.
- Corydoras Catfish✅ CompatiblePeaceful · 6.5 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 Diamond Tetra in a shoal of 6+ or it gets stressed and nippy.
- Keep Corydoras Catfish 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)
- Compatible on the things that matter: shared water near 23–27 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Diamond 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, and their water overlaps around 22–28 °C — no size, zone or temperament conflicts.
- Keep Diamond 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)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Diamond 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 Diamond 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)
- 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 Diamond 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; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Diamond 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)
- Compatible on the things that matter: shared water near 22–24 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Diamond 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, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Keep Diamond 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)
- 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 Diamond 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)
- Compatible on the things that matter: shared water near 22–23 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Diamond 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, and their water overlaps around 22–25 °C — no size, zone or temperament conflicts.
- Keep Diamond 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)
- 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 Diamond 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)
- Compatible on the things that matter: shared water near 23–27 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Diamond 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 Diamond 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)
- Both are peaceful, and their water overlaps around 23–28 °C — no size, zone or temperament conflicts.
- Keep Diamond 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.
- Spotfin Corydoras✅ CompatiblePeaceful · 6.5 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 Diamond Tetra in a shoal of 6+ or it gets stressed and nippy.
- Keep Spotfin Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Sterbai Corydoras✅ CompatiblePeaceful · 6.5 cm · Medium care · 24–30 °C (75–86 °F)
- Compatible on the things that matter: shared water near 24–28 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Diamond Tetra in a shoal of 6+ or it gets stressed and nippy.
- Keep Sterbai Corydoras 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)
- Expect Ash Lipped Apisto to harass Diamond Tetra at times; give dense cover and watch them at feeding.
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Diamond Tetra in a shoal of 6+ or it gets stressed and nippy.
- Banded Dwarf Cichlid⚠️ With cautionSemi-aggressive · 7 cm · Medium care · 24–30 °C (75–86 °F)
- Banded Dwarf Cichlid and Diamond Tetra are close in size, but the semi-aggressive one tends to dominate — add diamond tetra in a group to spread the pressure.
- Keep Diamond 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 is semi-aggressive and may chase or nip the smaller Diamond Tetra — plant heavily and break up sight lines.
- Keep Diamond 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)
- Expect Black Ruby Barb to harass Diamond 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 Diamond 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)
- Black Skirt Tetra and Diamond Tetra are close in size, but the semi-aggressive one tends to dominate — add diamond tetra in a group to spread the pressure.
- Keep Diamond 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.
- Bleeding Heart Tetra⚠️ With cautionSemi-aggressive · 7 cm · Medium care · 23–28 °C (73–82 °F)
- Bleeding Heart Tetra and Diamond Tetra are close in size, but the semi-aggressive one tends to dominate — add diamond 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 Diamond Tetra in a shoal of 6+ or it gets stressed and nippy.
- Keep Bleeding Heart Tetra in a shoal of 6+ or it gets stressed and nippy.
- Bright Diamond Tetra⚠️ With cautionPeaceful · 7 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 Diamond Tetra in a shoal of 6+ or it gets stressed and nippy.
- Keep Bright Diamond Tetra in a shoal of 8+ or it gets stressed and nippy.
- Colombian Tetra⚠️ With cautionSemi-aggressive · 6.5 cm · Easy care · 24–28 °C (75–82 °F)
- Colombian Tetra is semi-aggressive and may chase or nip the smaller Diamond Tetra — plant heavily and break up sight lines.
- Your 75 L tank is below the ~114 L this pairing really wants — crowding raises aggression.
- Keep Diamond 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 is semi-aggressive and may chase or nip the smaller Diamond Tetra — plant heavily and break up sight lines.
- Keep Diamond 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 Diamond 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 Diamond Tetra — plant heavily and break up sight lines.
- Keep Diamond 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 Diamond Tetra are close in size, but the semi-aggressive one tends to dominate — add diamond tetra in a group to spread the pressure.
- Keep Diamond 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.
- Odessa Barb⚠️ With cautionSemi-aggressive · 6 cm · Easy care · 20–26 °C (68–79 °F)
- Expect Odessa Barb to harass Diamond Tetra at times; give dense cover and watch them at feeding.
- Keep Diamond 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)
- Expect Peaceful Betta to harass Diamond Tetra at times; give dense cover and watch them at feeding.
- Keep Diamond 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 and Diamond Tetra are close in size, but the aggressive one tends to dominate — add diamond tetra in a group to spread the pressure.
- Keep Diamond 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 Diamond Tetra are close in size, but the semi-aggressive one tends to dominate — add diamond tetra in a group to spread the pressure.
- Keep Diamond 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)
- Diamond 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 Diamond 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 Diamond 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)
- Diamond Tetra is bite-sized to a 90 cm predatory clown knifefish — it will be eaten.
- Clown Knifefish is aggressive and may chase or nip the smaller Diamond 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 Diamond 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)
- Size gap is too large (100 vs 6 cm): Fire Eel will treat Diamond Tetra as food.
- Expect Fire Eel to harass Diamond Tetra at times; give dense cover and watch them at feeding.
- Your 75 L tank is below the ~380 L this pairing really wants — crowding raises aggression.
- Keep Diamond 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 6 cm Diamond Tetra whole.
- Your 75 L tank is below the ~3800 L this pairing really wants — crowding raises aggression.
- Keep Diamond 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)
- Diamond Tetra is bite-sized to a 120 cm predatory redtail catfish — it will be eaten.
- Redtail Catfish is aggressive and may chase or nip the smaller Diamond 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 Diamond 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)
- Size gap is too large (90 vs 6 cm): Spotted Gar will treat Diamond Tetra as food.
- Expect Spotted Gar to harass Diamond 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 Diamond 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)
- Size gap is too large (300 vs 6 cm): Wels Catfish will treat Diamond Tetra as food.
- Expect Wels Catfish to harass Diamond 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 Diamond 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 6 cm): Wolf Cichlid will treat Diamond Tetra as food.
- Expect Wolf Cichlid to harass Diamond Tetra at times; give dense cover and watch them at feeding.
- Your 75 L tank is below the ~760 L this pairing really wants — crowding raises aggression.
- Keep Diamond 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.
Diamond Tetra care specs
- Care level
- Easy
- Breeding
- Medium
- Max size
- 6 cm (2.4 in)
- Min tank size
- 60 L (15.9 gal)
- Temperature
- 22–28 °C (72–82 °F)
- pH
- 6–7.5
- Hardness
- 3–12 dGH
- Lifespan
- 3–5 years
- Diet
- Omnivore
- Swim level
- Middle
- Group size
- 6+ (shoaling)
- Family
- Characidae
- Origin
- Lake Valencia basin, Venezuela — slow, vegetated backwaters and leaf-littered streams
What is a Diamond Tetra?
The diamond tetra (Moenkhausia pittieri), also called the diamond characin or Pittier’s tetra, is a medium-small South American characid that earns its name honestly. Under the right light, every scale across the flanks throws off a prismatic violet-gold shimmer — not a simple metallic sheen, but a multi-angle iridescence that shifts from silver to purple to green as the fish turns. A settled shoal of eight or more moving through a planted tank is a genuinely impressive spectacle, and it’s achievable by any keeper with basic skills.
Despite that showiness, the diamond tetra is a hardy, undemanding fish. It tolerates a wide temperature band of 22–28 °C (72–82 °F), accepts most commercial foods, and presents no unusual water-chemistry demands. The main requirements are group size — lone fish are drab and stressed — and a layout that lets the iridescence do its thing. Get those two things right and the diamond tetra is one of the most rewarding midwater fish in the hobby.
Where do Diamond Tetras come from?
Diamond tetras are native to the Lake Valencia basin in Venezuela, one of South America’s largest endorheic (closed drainage) lakes and its surrounding slow-moving tributaries. Their natural habitat is shaded, heavily vegetated backwaters and leaf-littered, tannin-stained streams with gentle current and soft, slightly acidic water.
Lake Valencia is an unusual environment — isolated from larger river systems, warm year-round, and rich in aquatic plant growth. This origin explains the diamond tetra’s preferences in captivity: they do best in planted tanks with subdued to moderate lighting, some surface cover, soft-to-moderately-hard water, and minimal turbulence. The wild population is considered vulnerable due to lake pollution, so nearly all aquarium specimens are captive-bred.
What size tank does a Diamond Tetra need?
The minimum is 60 litres (16 gallons) for a proper shoal of six, but 80–120 L (21–32 gal) gives you the room to keep eight or more fish alongside a few bottom-dwellers — which is where this species looks its best. A longer footprint (60–90 cm / 24–36 in) is more useful than a tall tank, as diamond tetras are midwater swimmers that use horizontal space.
Plant the tank with fine-leaved midground and background plants (Java fern, Vallisneria, Cryptocoryne) and leave an open central swimming zone. A dark substrate — black sand or fine dark gravel — serves double duty: it reflects less light upward, creating the low-contrast backdrop that makes iridescent scales pop, and it mimics the natural leaf-littered bottom of the Lake Valencia basin. Add a gentle current from the filter; these are not sluggish-water fish, but a powerhead blasting them mid-tank is unnecessary.
What water parameters do Diamond Tetras need?
- Temperature: 22–28 °C (72–82 °F) — they tolerate a wide range, but 24–26 °C (75–79 °F) is the comfort zone.
- pH: 6.0–7.5. Soft, slightly acidic water best replicates the Lake Valencia basin.
- Hardness: 3–12 dGH (soft to moderately hard). Very hard tap water above ~15 dGH is suboptimal long-term.
Stability matters more than chasing exact numbers within that range. Cycle the tank fully before adding fish, and maintain weekly partial water changes of 25–30%. Wild-type water chemistry is soft and acidic, but captive-bred fish (which is what you’ll find in stores) adapt to neutral, moderately hard tap water without issues, as long as extremes are avoided.
What do Diamond Tetras eat?
Diamond tetras are omnivores with a preference for small, protein-rich items. In the wild they consume insects, zooplankton, algae, and plant matter. In captivity they accept a wide range of foods readily:
- Staple: Quality small flake food or micro-pellets sized for tetras, fed once or twice daily in amounts consumed within two minutes.
- Enrichment: Frozen or live daphnia, baby brine shrimp, and small bloodworm two or three times a week. These high-protein items improve colour intensity and are important for bringing fish into breeding condition.
- Supplemental: Blanched spinach or spirulina flake covers the plant-matter side of their omnivore diet.
Variety is the key. A flake-only diet produces pale, less active fish. Rotate in live or frozen foods regularly and the difference in shimmer and activity is visible within a few weeks.
Are Diamond Tetras aggressive — and what fish can live with them?
Diamond tetras are peaceful and suitable for most community setups, with one caveat: males can be mildly nippy toward fish with long, flowing fins — particularly bettas and angelfish — especially in smaller tanks where territorial displays are more compressed. This is not consistent aggression but opportunistic fin-nipping, and it’s best managed by simply avoiding long-finned tankmates rather than hoping individuals behave.
With appropriate companions they are calm, active midwater fish. Good tankmates include:
- Other tetras of similar size (black skirt tetra, lemon tetra, rummy-nose tetra)
- Corydoras species and other small bottom-dwellers
- Dwarf gouramis (provided the tank is large enough for retreat space)
- Rasboras and other peaceful South American or Southeast Asian community fish
- Small plecos (bristlenose, otocinclus)
Avoid cichlids large enough to eat them, highly aggressive fin-nippers like tiger barbs in small numbers, and any species that occupies the middle column aggressively. For a full rundown of compatible and incompatible pairings, see Diamond Tetra tank mates.
How do you tell male and female Diamond Tetras apart?
Sexing adult diamond tetras is not difficult once you know what to look for. Males are slimmer in body depth, develop a distinctly taller and more pointed dorsal fin (one of the most reliable visual cues), and display a noticeably stronger iridescent sheen — the shimmer that gives the species its name is most vivid on males in good condition. In a group, males often fan and display their dorsal fins toward each other in low-level competitive posturing.
Females are deeper-bodied and noticeably fuller, especially when carrying eggs. Their dorsal fin is shorter and more rounded, and their overall shimmer, while still attractive, is less intense than a well-conditioned male. When gravid, the rounded belly makes females easy to identify at a glance.
How do Diamond Tetras breed?
Diamond tetras are egg scatterers and breed in a style typical of many characids — moderately straightforward once the conditions are right, but requiring some advance preparation. Breeding difficulty is rated medium.
To trigger spawning, set up a dedicated breeding tank of around 40–60 L with very soft, slightly acidic water (pH 6.0–6.5, hardness below 5 dGH), a temperature of about 26 °C (79 °F), and dim lighting. Fine-leaved plants such as Java moss or a spawning mop give the fish a surface to scatter eggs onto. Condition a pair or small group on live and frozen foods for one to two weeks before moving them to the breeding tank.
Spawning typically occurs in the early morning. Eggs are small, adhesive, and semi-transparent. Remove the adults immediately after spawning — diamond tetras, like most characids, will eat their own eggs without hesitation. Eggs hatch in roughly 24–36 hours at 26 °C, and fry become free-swimming after another two to three days. First foods are infusoria or commercial fry powder; progress to freshly hatched baby brine shrimp as the fry grow.
What are common Diamond Tetra diseases?
Diamond tetras share the usual disease vulnerabilities of small community fish. The most common issues are:
- Ich (white spot disease): Fine white spots resembling salt grains on the fins and body. Almost always triggered by a temperature drop, introduction of an infected fish, or poor water quality.
- Fin rot: Ragged or receding fin edges, usually bacterial in origin and directly linked to deteriorating water conditions.
- Velvet (Oodinium): A dusty gold or rust-coloured dusting on the body, often accompanied by flashing (rubbing against objects). More easily missed than ich.
- Internal parasites: Hollow belly or persistent weight loss despite good feeding. More common in wild-caught specimens; captive-bred fish are rarely affected.
Prevention covers the vast majority of these: a fully cycled tank, stable temperature, weekly water changes, and quarantining new fish for two to four weeks before introduction. A stressed shoal kept below minimum group size is significantly more susceptible to disease outbreaks.
Health note: disease identification and medication dosing are beyond the scope of a care profile. Before treating, confirm symptoms against a reputable veterinary or fish-health source — misdiagnosis and inappropriate medication can do more harm than the original condition.
How long do Diamond Tetras live?
A well-kept diamond tetra lives 3–5 years. The full lifespan is achievable with consistent care: a properly sized shoal in a stable, planted tank with varied feeding and regular water maintenance. Fish kept in undersized groups, with poor water quality, or fed a monotonous diet typically fall well short of that range and tend to show faded colour and reduced activity before the end.
Because diamond tetras are almost entirely captive-bred, you are typically buying young fish with most of their lifespan ahead of them — a contrast to species that are often sold as adults. Give them the right conditions from the start and the iridescent display they put on will reward you for several years.
Frequently asked questions
How many diamond tetras should I keep together?
Keep at least six — ideally eight or more. Diamond tetras are a true shoaling species and lone individuals or small groups become shy and may nip fins. A proper group distributes any minor squabbling and coaxes the males into displaying their best iridescence, which is the whole point of keeping them.
Why are my diamond tetras not sparkling?
Two common culprits: lighting and stress. Their scales need the right angle of light to fire up — medium-intensity, slightly warm LEDs over a dark substrate and a planted background produce the best effect. Stress from a small group, incompatible tankmates, or poor water quality also dulls the sheen. Aim for soft-to-moderately-hard, slightly acidic water and a settled shoal.
What you need to keep a diamond 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 diamond tetra in the current, and a tight-fitting lid. Cycle the tank fully before adding any fish.
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