Photo: Sascha Biedermann (CC BY-SA 2.5) — via Wikimedia Commons
Green Neon Tetra (Paracheirodon simulans)
The smallest of the neon trio — a shimmering, neon-blue schooling fish that thrives only in soft, acidic blackwater and rewards the patient aquarist with dazzling displays.
Will it live with a Green Neon Tetra?
We compare each fish against your green neon tetra on temperament, size, water parameters and swimming zone. Set your tank size and filter the results.
- Blackwing Hatchetfish✅ CompatiblePeaceful · 3.5 cm · Medium care · 23–28 °C (73–82 °F)
- Both are peaceful, and their water overlaps around 24–28 °C — no size, zone or temperament conflicts.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Blackwing Hatchetfish in a shoal of 6+ or it gets stressed and nippy.
- Celestial Pearl Danio✅ CompatiblePeaceful · 2 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.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Celestial Pearl Danio in a shoal of 6+ or it gets stressed and nippy.
- Chili Rasbora✅ CompatiblePeaceful · 2 cm · Medium care · 22–28 °C (72–82 °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 Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Chili Rasbora in a shoal of 8+ or it gets stressed and nippy.
- Clown Killifish✅ CompatiblePeaceful · 3.5 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 Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Clown Killifish in a shoal of 6+ or it gets stressed and nippy.
- Crimson Red Betta✅ CompatiblePeaceful · 3.5 cm · Hard 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.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Crystal Red Shrimp✅ CompatiblePeaceful · 2.5 cm · Hard care · 20–24 °C (68–75 °F)
- Both are peaceful, and their water overlaps around 24–24 °C — no size, zone or temperament conflicts.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Crystal Red Shrimp in a shoal of 10+ or it gets stressed and nippy.
- Dawn Tetra✅ CompatiblePeaceful · 2.5 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.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Dawn Tetra in a shoal of 8+ or it gets stressed and nippy.
- Dwarf Spotted Rasbora✅ CompatiblePeaceful · 2.5 cm · Medium care · 23–28 °C (73–82 °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 Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Dwarf Spotted Rasbora in a shoal of 8+ or it gets stressed and nippy.
- Ember Tetra✅ CompatiblePeaceful · 2 cm · Easy 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 Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Ember Tetra in a shoal of 8+ or it gets stressed and nippy.
- Exclamation Point Rasbora✅ CompatiblePeaceful · 2 cm · Medium 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 Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Exclamation Point Rasbora in a shoal of 8+ or it gets stressed and nippy.
- Eyespot Rasbora✅ CompatiblePeaceful · 3.5 cm · Medium care · 20–25 °C (68–77 °F)
- Both are peaceful, and their water overlaps around 24–25 °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 Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Eyespot Rasbora in a shoal of 8+ or it gets stressed and nippy.
- Glowlight Danio✅ CompatiblePeaceful · 3 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.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Glowlight Danio in a shoal of 8+ or it gets stressed and nippy.
- Gold Ring Danio✅ CompatiblePeaceful · 3 cm · Easy care · 18–26 °C (64–79 °F)
- Both are peaceful, and their water overlaps around 24–26 °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 Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Gold Ring Danio in a shoal of 8+ or it gets stressed and nippy.
- Hummingbird Tetra✅ CompatiblePeaceful · 1.8 cm · Hard care · 22–27 °C (72–81 °F)
- Both are peaceful, and their water overlaps around 24–27 °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 Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Hummingbird Tetra in a shoal of 8+ or it gets stressed and nippy.
- Lambchop Rasbora✅ CompatiblePeaceful · 3 cm · Medium 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.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Neon Blue Rasbora✅ CompatiblePeaceful · 2.5 cm · Medium 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.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Neon Blue Rasbora in a shoal of 10+ or it gets stressed and nippy.
- Neon Green Rasbora✅ CompatiblePeaceful · 2 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.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Neon Green Rasbora in a shoal of 10+ or it gets stressed and nippy.
- Neon Tetra✅ CompatiblePeaceful · 3 cm · Easy care · 20–26 °C (68–79 °F)
- Compatible on the things that matter: shared water near 24–26 °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 Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Neon Tetra in a shoal of 6+ or it gets stressed and nippy.
- Pygmy Corydoras✅ CompatiblePeaceful · 3.2 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 Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Pygmy Corydoras in a shoal of 8+ or it gets stressed and nippy.
- Ruby Tetra✅ CompatiblePeaceful · 2 cm · Medium care · 23–28 °C (73–82 °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 Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Ruby Tetra in a shoal of 8+ or it gets stressed and nippy.
- Scarlet Badis✅ CompatibleSemi-aggressive · 2 cm · Medium care · 22–27 °C (72–81 °F)
- Compatible on the things that matter: shared water near 24–27 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Strawberry Rasbora✅ CompatiblePeaceful · 2 cm · Medium care · 23–28 °C (73–82 °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 Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Strawberry Rasbora in a shoal of 8+ or it gets stressed and nippy.
- Tail-spot Corydoras✅ CompatiblePeaceful · 3 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.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Tail-spot Corydoras in a shoal of 8+ or it gets stressed and nippy.
- Tiger Shrimp✅ CompatiblePeaceful · 3 cm · Hard 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 Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Tiger Shrimp in a shoal of 6+ or it gets stressed and nippy.
- African Dwarf Frog⚠️ With cautionPeaceful · 4 cm · Medium care · 22–26 °C (72–79 °F)
- pH preferences only just meet (Green Neon Tetra 4.5–6.5 vs African Dwarf Frog 6.8–7.8) — target the overlap and acclimate slowly.
- One likes softer water and the other harder (0–4 vs 5–12 dGH) — a compromise, not a perfect match.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Assassin Snail⚠️ With cautionPeaceful · 3 cm · Easy care · 22–26 °C (72–79 °F)
- Water hardness preferences differ (Green Neon Tetra 0–4 vs Assassin Snail 8–20 dGH).
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Black Darter Tetra⚠️ With cautionSemi-aggressive · 4 cm · Hard care · 21–28 °C (70–82 °F)
- Expect Black Darter Tetra to harass Green Neon Tetra at times; give dense cover and watch them at feeding.
- Black Darter Tetra may hunt Green Neon Tetra, fry or shrimplets — safest in a heavily planted tank.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Blue Danio⚠️ With cautionPeaceful · 4 cm · Easy care · 21–26 °C (70–79 °F)
- One likes softer water and the other harder (0–4 vs 5–15 dGH) — a compromise, not a perfect match.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Blue Danio in a shoal of 6+ or it gets stressed and nippy.
- Cherry Shrimp⚠️ With cautionPeaceful · 3 cm · Easy care · 18–28 °C (64–82 °F)
- Water hardness preferences differ (Green Neon Tetra 0–4 vs Cherry Shrimp 6–15 dGH).
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Cherry Shrimp in a shoal of 10+ or it gets stressed and nippy.
- Emerald Dwarf Danio⚠️ With cautionPeaceful · 2 cm · Medium care · 20–24 °C (68–75 °F)
- Different pH ranges (4.5–6.5 vs 7–8); doable if you sit in the shared band, but not ideal long-term.
- Water hardness preferences differ (Green Neon Tetra 0–4 vs Emerald Dwarf Danio 5–12 dGH).
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Emerald Dwarf Danio in a shoal of 8+ or it gets stressed and nippy.
- Endler's Livebearer⚠️ With cautionPeaceful · 3 cm · Easy care · 22–28 °C (72–82 °F)
- Different pH ranges (4.5–6.5 vs 7–8.5); doable if you sit in the shared band, but not ideal long-term.
- Water hardness preferences differ (Green Neon Tetra 0–4 vs Endler's Livebearer 10–25 dGH).
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Endler's Livebearer in a shoal of 6+ or it gets stressed and nippy.
- Malaysian Trumpet Snail⚠️ With cautionPeaceful · 3 cm · Easy care · 21–27 °C (70–81 °F)
- Different pH ranges (4.5–6.5 vs 7–8); doable if you sit in the shared band, but not ideal long-term.
- Water hardness preferences differ (Green Neon Tetra 0–4 vs Malaysian Trumpet Snail 8–18 dGH).
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Nerite Snail⚠️ With cautionPeaceful · 2.5 cm · Easy care · 22–28 °C (72–82 °F)
- Different pH ranges (4.5–6.5 vs 7–8.5); doable if you sit in the shared band, but not ideal long-term.
- Water hardness preferences differ (Green Neon Tetra 0–4 vs Nerite Snail 8–18 dGH).
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Pea Puffer⚠️ With cautionSemi-aggressive · 2.5 cm · Medium care · 24–28 °C (75–82 °F)
- Water hardness preferences differ (Green Neon Tetra 0–4 vs Pea Puffer 5–15 dGH).
- Expect Pea Puffer to harass Green Neon Tetra at times; give dense cover and watch them at feeding.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Rainbow Emperor Tetra⚠️ With cautionSemi-aggressive · 3.6 cm · Medium care · 22–28 °C (72–82 °F)
- Expect Rainbow Emperor Tetra to harass Green Neon Tetra at times; give dense cover and watch them at feeding.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Rainbow Emperor Tetra in a shoal of 8+ or it gets stressed and nippy.
- Ramshorn Snail⚠️ With cautionPeaceful · 2 cm · Easy care · 20–28 °C (68–82 °F)
- pH preferences only just meet (Green Neon Tetra 4.5–6.5 vs Ramshorn Snail 7–8) — target the overlap and acclimate slowly.
- One likes softer water and the other harder (0–4 vs 5–15 dGH) — a compromise, not a perfect match.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Red Lip Nerite Snail⚠️ With cautionPeaceful · 2 cm · Easy care · 22–28 °C (72–82 °F)
- Different pH ranges (4.5–6.5 vs 7–8); doable if you sit in the shared band, but not ideal long-term.
- Water hardness preferences differ (Green Neon Tetra 0–4 vs Red Lip Nerite Snail 6–18 dGH).
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Rummy Nose Rasbora⚠️ With cautionPeaceful · 4 cm · Medium care · 20–26 °C (68–79 °F)
- Different pH ranges (4.5–6.5 vs 7–8); doable if you sit in the shared band, but not ideal long-term.
- Water hardness preferences differ (Green Neon Tetra 0–4 vs Rummy Nose Rasbora 8–16 dGH).
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Rummy Nose Rasbora in a shoal of 8+ or it gets stressed and nippy.
- Serpae Tetra⚠️ With cautionSemi-aggressive · 4 cm · Easy care · 23–28 °C (73–82 °F)
- Serpae Tetra is semi-aggressive and may chase or nip the smaller Green Neon Tetra — plant heavily and break up sight lines.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Keep Serpae Tetra in a shoal of 6+ or it gets stressed and nippy.
- Trinidad Guppy⚠️ With cautionPeaceful · 3 cm · Easy care · 19–24 °C (66–75 °F)
- Different pH ranges (4.5–6.5 vs 6.6–7.5); doable if you sit in the shared band, but not ideal long-term.
- Water hardness preferences differ (Green Neon Tetra 0–4 vs Trinidad Guppy 5–15 dGH).
- Keep Green Neon 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)
- Alligator Gar (250 cm) is big enough to swallow the 2.5 cm Green Neon Tetra whole.
- pH preferences only just meet (Green Neon Tetra 4.5–6.5 vs Alligator Gar 6.8–7.8) — target the overlap and acclimate slowly.
- Alligator Gar clearly outsizes Green Neon Tetra and is aggressive; risky unless the tank is big and well-planted.
- Your 75 L tank is below the ~3785 L this pairing really wants — crowding raises aggression.
- Keep Green Neon 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)
- Green Neon Tetra is bite-sized to a 90 cm predatory clown knifefish — it will be eaten.
- Water hardness preferences differ (Green Neon Tetra 0–4 vs Clown Knifefish 5–15 dGH).
- Clown Knifefish clearly outsizes Green Neon 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 Green Neon 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 2.5 cm): Fire Eel will treat Green Neon Tetra as food.
- Water hardness preferences differ (Green Neon Tetra 0–4 vs Fire Eel 5–15 dGH).
- Fire Eel clearly outsizes Green Neon 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 Green Neon 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)
- Green Neon Tetra is bite-sized to a 90 cm koi — it will be eaten.
- Water hardness preferences differ (Green Neon Tetra 0–4 vs Koi 9–18 dGH).
- Your 75 L tank is below the ~3800 L this pairing really wants — crowding raises aggression.
- Keep Green Neon 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)
- Redtail Catfish (120 cm) is big enough to swallow the 2.5 cm Green Neon Tetra whole.
- Redtail Catfish clearly outsizes Green Neon Tetra and is aggressive; risky unless the tank is big and well-planted.
- Your 75 L tank is below the ~5700 L this pairing really wants — crowding raises aggression.
- Keep Green Neon 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)
- Green Neon Tetra is bite-sized to a 90 cm predatory spotted gar — it will be eaten.
- Spotted Gar is aggressive and may chase or nip the smaller Green Neon Tetra — plant heavily and break up sight lines.
- Your 75 L tank is below the ~600 L this pairing really wants — crowding raises aggression.
- Keep Green Neon 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 2.5 cm Green Neon Tetra whole.
- One likes softer water and the other harder (0–4 vs 5–15 dGH) — a compromise, not a perfect match.
- Expect Wels Catfish to harass Green Neon 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 Green Neon 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)
- Green Neon Tetra is bite-sized to a 72 cm predatory wolf cichlid — it will be eaten.
- Different pH ranges (4.5–6.5 vs 7–8); doable if you sit in the shared band, but not ideal long-term.
- Water hardness preferences differ (Green Neon Tetra 0–4 vs Wolf Cichlid 8–20 dGH).
- Wolf Cichlid clearly outsizes Green Neon 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 Green Neon 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.
Green Neon Tetra care specs
- Care level
- Hard
- Breeding
- Very Hard
- Max size
- 2.5 cm (1 in)
- Min tank size
- 60 L (15.9 gal)
- Temperature
- 24–28 °C (75–82 °F)
- pH
- 4.5–6.5
- Hardness
- 0–4 dGH
- Lifespan
- 3–5 years
- Diet
- Omnivore
- Swim level
- Middle
- Group size
- 8+ (shoaling)
- Family
- Characidae
- Origin
- South America — upper Rio Negro and Orinoco tributaries in Venezuela and Colombia
What is a Green Neon Tetra?
The Green Neon Tetra (Paracheirodon simulans) is the smallest and rarest of the three Paracheirodon species — closely related to the Neon Tetra (P. innesi) and Cardinal Tetra (P. axelrodi), yet distinct in both appearance and care demands. At just 2.5 cm (1 in), it is genuinely tiny, but a school of ten or more in a dimly lit blackwater aquarium is one of the most visually striking sights in the freshwater hobby.
The iridescent blue-green stripe runs almost the full length of the body, glowing intensely against dark substrate and tannin-stained water. The red ventral patch is smaller than in either related species and restricted to the rear of the belly, giving the fish a cleaner, more uniformly blue-green silhouette. It belongs to the family Characidae and is classified as a peaceful omnivore that occupies the middle water column.
This is not a fish for beginners. Its tolerance for water-chemistry error is minimal, it is almost exclusively wild-caught, and it punishes even modest lapses in water quality. For the aquarist willing to invest in a proper blackwater setup, however, it offers a reward that few other small fish can match.
Where do Green Neon Tetras come from in the wild?
Green Neon Tetras originate from remote blackwater tributaries of the upper Rio Negro and the Orinoco basin in southern Venezuela and north-western Colombia — some of the most mineral-free, acidic waters on Earth. The water here is stained dark amber by tannins and humic acids leaching from decomposing leaf litter and submerged wood. pH regularly dips below 5.0, hardness is virtually zero, and total dissolved solids are extremely low.
Temperatures in these forest streams range from 24–28 °C (75–82 °F), light is filtered through a dense forest canopy, and the current is gentle. The fish spend most of their time in mid-water, schooling among submerged roots and fallen leaves. Because captive breeding at this level of water chemistry is very difficult, most individuals available in the trade are still wild-collected. Responsible sourcing matters.
What tank size and setup do Green Neon Tetras need?
The minimum recommended tank size is 60 litres (16 gal), and larger is always better when maintaining stable soft, acidic chemistry. A 60–80 L (16–21 gal) aquarium gives a school of 8–12 fish adequate swimming space and enough water volume to buffer against rapid parameter swings — the real enemy of this species.
Replicate their blackwater habitat as closely as possible:
- Substrate: Dark sand or fine gravel. Dark substrate intensifies the fish’s colour and reduces stress.
- Tannin sources: Indian almond (catappa) leaves, alder cones, and driftwood are essential. They release humic acids and tannins that acidify the water and create the amber staining the fish are adapted to.
- Filtration: A gentle sponge filter or output baffle on a canister filter. These fish are small and fragile; strong current stresses them, and delicate fry can be pulled into intakes.
- Lighting: Subdued. Low-intensity lighting suits their natural habitat and makes their neon stripe flash more dramatically. Floating plants help diffuse overhead light.
- Plants: Java fern (Microsorum pteropus), Anubias species, and Java moss all tolerate very soft, acidic water. Avoid fertiliser-hungry stem plants that require harder, more mineralised water.
A tight-fitting lid is recommended — small tetras are capable jumpers.
What water parameters do Green Neon Tetras require?
This is the defining challenge of the species. The parameters must be genuinely extreme by typical fishkeeping standards:
- Temperature: 24–28 °C (75–82 °F)
- pH: 4.5–6.5 — soft, acidic blackwater. Aim for 5.5–6.0 as a practical target.
- Hardness: 0–4 dGH — nearly distilled water. Tap water in most regions is far too hard.
- TDS (total dissolved solids): Very low; aim below 100 ppm.
Achieving these parameters almost always requires RO (reverse osmosis) water remineralised to a very low GH, combined with tannin sources to drive the pH down. Regular testing is non-negotiable. Even a modest rise toward neutral pH — which can happen if a filter runs out of acidifying media or leaf litter is removed — can stress or kill the fish over days to weeks. Stability within the correct range matters as much as hitting the exact numbers.
What do Green Neon Tetras eat?
Green Neon Tetras are omnivores, but their tiny mouth size — consistent with a 2.5 cm (1 in) fish — dictates what they can actually eat. In the wild they feed on micro-invertebrates, zooplankton, and small organic particles.
In the aquarium, suitable foods include:
- Dry foods: High-quality micro-pellets or finely crushed flake sized appropriately for a very small mouth. Standard-sized pellets are too large.
- Frozen and live foods: Baby brine shrimp (artemia nauplii), micro worms, daphnia, and cyclops. These stimulate natural feeding behaviour and maintain condition.
- Frequency: Feed small amounts twice daily. These fish have tiny stomachs — a little, often is better than one large feed. Remove uneaten food promptly to protect water quality in an already delicate system.
Variety helps keep fish in prime condition, and frozen foods in particular trigger strong feeding responses that are satisfying to watch in a school.
How do Green Neon Tetras behave, and what fish can live with them?
Green Neon Tetras are peaceful schooling fish that pose no threat to any tank mate. However, their extremely demanding water parameters are the primary constraint on compatibility — most common community fish simply cannot thrive in pH 4.5–6.5, 0–4 dGH water.
Keep a minimum group of 8; 12–15 is better. Below the minimum group size they become shy, spend time hidden, and their natural schooling behaviour — the main visual appeal of the species — breaks down. In a proper school and the right environment they occupy the middle column actively throughout the day.
Compatible tank mates must share their need for soft, acidic blackwater. Good options include:
- Other small soft-water characins (hatchetfish, some pencilfish)
- Dwarf cichlids adapted to blackwater conditions (such as Apistogramma species, kept with care given their predatory potential toward small fish)
- Corydoras species from soft-water regions
- Small, peaceful loricariids
- Freshwater shrimp are risky — dwarf shrimp may become occasional prey given the size mismatch, and their own sensitivity to water chemistry must be matched
For a detailed, filterable list of suitable companions, see Green Neon Tetra tank mates.
Avoid mixing with Neon Tetras or Cardinal Tetras. Beyond the water-parameter differences, there is a disease-transmission risk: the three species share susceptibility to Paracheirodon disease (Neon Tetra Disease), and mixing strains from different sources increases exposure risk.
How do you tell male and female Green Neon Tetras apart?
Sexual dimorphism in this species is subtle. Females are slightly larger overall and noticeably more rounded in the abdomen, particularly when in condition for breeding. Males are slimmer with a straighter ventral line. There are no significant differences in colouration or fin shape between the sexes.
Reliable sexing requires observing fish that are well-fed and in good condition over time, rather than at a glance in a store tank. Even experienced aquarists can find individual fish difficult to sex with confidence. For most keepers this is purely academic — unless breeding is the goal, a mixed group purchased in quantity will inevitably include both sexes.
How do Green Neon Tetras breed?
Breeding is rated very hard and is rarely accomplished outside specialist facilities with dedicated breeding setups. The requirements push beyond even normal blackwater maintenance:
- Water: pH as low as 5.0–5.5, hardness approaching 0 dGH, and very low conductivity are typically necessary to trigger spawning.
- Conditioning: The pair or group must be conditioned with high-quality live and frozen foods over several weeks.
- Spawning setup: A dedicated breeding tank with dim lighting, fine-leaved plants or spawning mops, and no substrate (to aid egg collection). Eggs are adhesive and scattered among plants.
- Egg and fry care: Eggs are light-sensitive and must be kept in near-darkness. Fry are extremely small on hatching and require infusoria or commercially prepared fry food before graduating to baby brine shrimp nauplii.
- Adult removal: Adults will eat eggs and fry; remove parents after spawning.
The difficulty of meeting all these requirements simultaneously explains why nearly all commercially available fish are wild-caught. Successful captive breeding is documented but uncommon, and those who achieve it typically specialise in soft-water characins.
What diseases are common in Green Neon Tetras, and how do you prevent them?
Green Neon Tetras are fragile and vulnerable to several conditions, most of which trace back to water quality or inappropriate parameters:
- Neon Tetra Disease (Pleistophora hyphessobryconis): A microsporidian parasite that causes progressive colour fading, curved spine, bloating, and restlessness. There is no reliable cure. Prevention is the only tool: buy from reputable sources, quarantine all new fish for at least four weeks before adding them to an established tank, and avoid mixing fish from different source tanks.
- Ich (Ichthyophthirius multifiliis): White spots on body and fins. Most often triggered by temperature fluctuations or stress. Maintain stable temperature in the 24–28 °C range and keep water pristine.
- Bacterial infections and fin damage: Rapid deterioration in soft-water tanks is almost always linked to a water-quality lapse — a missed water change, a rise in pH, or a spike in nitrates. Weekly water changes and consistent parameter monitoring are the primary prevention.
- Wasting/failure to thrive: Often the result of wrong water chemistry. Fish kept in water that is too hard or too alkaline will slowly decline even without a specific pathogen present.
Health note: Medication dosing and specific disease diagnosis are beyond the scope of a care profile. For sick fish, confirm symptoms carefully against a reliable fish-health resource before medicating — many standard medications alter pH or use sodium chloride, both of which are problematic in a soft-water blackwater system.
How long do Green Neon Tetras live?
With optimal care in appropriate blackwater conditions, Green Neon Tetras can live 3–5 years. In practice, lifespan in captivity often falls short of this — usually because water parameters drift out of range over time, or because the fish were already stressed during collection and shipping. Wild-caught fish undergo significant physiological stress between the Rio Negro and the retailer’s tank.
The best investment in longevity is the setup itself: a mature, stable blackwater aquarium with consistent soft, acidic water, regular small water changes using RO water, and a school large enough that the fish remain confident and active. Get those fundamentals right, and Green Neon Tetras will deliver years of their extraordinary, glowing display.
Frequently asked questions
What is the difference between the Green Neon Tetra and the Neon Tetra?
The Green Neon Tetra (Paracheirodon simulans) is smaller (~2.5 cm vs ~4 cm), has a longer, brighter blue-green stripe running almost the full body length, and a much smaller red patch confined to the rear of the belly. It is also significantly more demanding — requiring very soft, acidic blackwater conditions (pH 4.5–6.5, hardness near 0 dGH) that are harsher than what Neon Tetras need. Keep them separate; their water requirements are not fully compatible.
Can I keep Green Neon Tetras in a planted tank?
Yes, a densely planted blackwater aquarium is ideal. Use soft, peat-filtered or RO water, leaf litter (Indian almond leaves), driftwood to lower pH, and subdued lighting. Hardy low-light plants like java fern, Anubias, and mosses suit the very soft, acidic water they need. Avoid CO2-rich, fertiliser-heavy Dutch planted tanks — the harder, more mineralised water typical of those setups will stress Green Neons.
What you need to keep a green neon tetra
The baseline is a heated, filtered 60 L+ tank: a reliable heater to hold 24–28 °C (75–82 °F), a gentle filter that won't batter a green neon tetra in the current, and a tight-fitting lid. Cycle the tank fully before adding any fish.
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