GloFish Tetra (Gymnocorymbus ternetzi (GM))
The same tough, shoaling tetra you know — now in electric reds, greens, and oranges that glow under blue LED lighting.
Will it live with a GloFish Tetra?
We compare each fish against your glofish 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)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Keep GloFish 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)
- 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 GloFish 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)
- 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 GloFish 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)
- Compatible on the things that matter: shared water near 22–27 °C, workable temperaments, and no predator-and-prey size gap.
- Keep GloFish 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.
- 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 GloFish 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)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 21–24 °C — no size, zone or temperament conflicts.
- Keep GloFish Tetra in a shoal of 6+ or it gets stressed and nippy.
- Celebes Rainbowfish✅ CompatiblePeaceful · 7 cm · Medium 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 GloFish Tetra in a shoal of 6+ or it gets stressed and nippy.
- Keep Celebes Rainbowfish 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)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Keep GloFish 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.
- Costa's Tetra✅ CompatiblePeaceful · 7 cm · Easy care · 22–28 °C (72–82 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–28 °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 GloFish Tetra in a shoal of 6+ or it gets stressed and nippy.
- Keep Costa's 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 23–27 °C — no size, zone or temperament conflicts.
- Keep GloFish 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)
- 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 GloFish 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)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Keep GloFish 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)
- Compatible on the things that matter: shared water near 27–28 °C, workable temperaments, and no predator-and-prey size gap.
- Keep GloFish 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)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 21–24 °C — no size, zone or temperament conflicts.
- Keep GloFish 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)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Keep GloFish 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.
- Panda Loach✅ CompatiblePeaceful · 6 cm · Hard care · 18–23 °C (64–73 °F)
- Compatible on the things that matter: shared water near 21–23 °C, workable temperaments, and no predator-and-prey size gap.
- Keep GloFish Tetra in a shoal of 6+ or it gets stressed and nippy.
- Peacock Gudgeon✅ CompatiblePeaceful · 7 cm · Medium care · 22–28 °C (72–82 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–28 °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 GloFish Tetra in a shoal of 6+ or it gets stressed and nippy.
- Peppered Corydoras✅ CompatiblePeaceful · 7 cm · Easy care · 18–26 °C (64–79 °F)
- Compatible on the things that matter: shared water near 21–26 °C, workable temperaments, and no predator-and-prey size gap.
- Keep GloFish Tetra in a shoal of 6+ or it gets stressed and nippy.
- Keep Peppered Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Rio Negro Checkerboard Cichlid✅ CompatiblePeaceful · 7 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.
- Keep GloFish 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)
- 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 GloFish 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.
- Slate Corydoras✅ CompatiblePeaceful · 6 cm · Medium care · 23–28 °C (73–82 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 23–28 °C — no size, zone or temperament conflicts.
- Keep GloFish 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)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Keep GloFish 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.
- Spotted Corydoras✅ CompatiblePeaceful · 7 cm · Easy care · 22–27 °C (72–81 °F)
- Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–27 °C — no size, zone or temperament conflicts.
- Keep GloFish Tetra in a shoal of 6+ or it gets stressed and nippy.
- Keep Spotted 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)
- 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 GloFish 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.
- Black Ruby Barb⚠️ With cautionSemi-aggressive · 6 cm · Easy care · 22–26 °C (72–79 °F)
- GloFish Tetra and Black Ruby Barb can both be territorial; doable with space and dense planting, but watch for chasing.
- Your 75 L tank is below the ~100 L this pairing really wants — crowding raises aggression.
- Keep GloFish 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)
- GloFish Tetra and Black Skirt Tetra can both be territorial; doable with space and dense planting, but watch for chasing.
- Keep GloFish 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.
- Blackline Rasbora⚠️ With cautionPeaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
- Expect GloFish Tetra to harass Blackline Rasbora at times; give dense cover and watch them at feeding.
- Keep GloFish 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.
- Desert Goby⚠️ With cautionSemi-aggressive · 6 cm · Easy care · 18–28 °C (64–82 °F)
- Both are a bit pushy (semi-aggressive + semi-aggressive) — workable only in a larger tank with cover and broken sight lines.
- Keep GloFish Tetra in a shoal of 6+ or it gets stressed and nippy.
- Diamond Tetra⚠️ With cautionPeaceful · 6 cm · Easy care · 22–28 °C (72–82 °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 GloFish 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.
- 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 GloFish 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)
- Both are a bit pushy (semi-aggressive + semi-aggressive) — workable only in a larger tank with cover and broken sight lines.
- Keep GloFish Tetra in a shoal of 6+ or it gets stressed and nippy.
- Glass Bloodfin Tetra⚠️ With cautionPeaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
- Expect GloFish Tetra to harass Glass Bloodfin Tetra at times; give dense cover and watch them at feeding.
- Keep GloFish 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⚠️ With cautionPeaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
- GloFish Tetra and Guppy are close in size, but the semi-aggressive one tends to dominate — add guppy in a group to spread the pressure.
- Keep GloFish Tetra in a shoal of 6+ or it gets stressed and nippy.
- Neon Dwarf Rainbowfish⚠️ With cautionPeaceful · 6 cm · Easy care · 23–27 °C (73–81 °F)
- GloFish Tetra and Neon Dwarf Rainbowfish are close in size, but the semi-aggressive one tends to dominate — add neon dwarf rainbowfish in a group to spread the pressure.
- Keep GloFish 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.
- Odessa Barb⚠️ With cautionSemi-aggressive · 6 cm · Easy care · 20–26 °C (68–79 °F)
- Both are a bit pushy (semi-aggressive + semi-aggressive) — workable only in a larger tank with cover and broken sight lines.
- Keep GloFish 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)
- GloFish Tetra and Peaceful Betta can both be territorial; doable with space and dense planting, but watch for chasing.
- Keep GloFish Tetra in a shoal of 6+ or it gets stressed and nippy.
- Pearl Danio⚠️ With cautionPeaceful · 6 cm · Easy care · 20–25 °C (68–77 °F)
- Expect GloFish Tetra to harass Pearl Danio at times; give dense cover and watch them at feeding.
- Keep GloFish 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⚠️ With cautionPeaceful · 6 cm · Easy care · 21–28 °C (70–82 °F)
- GloFish Tetra and Platy are close in size, but the semi-aggressive one tends to dominate — add platy in a group to spread the pressure.
- Keep GloFish Tetra in a shoal of 6+ or it gets stressed and nippy.
- Samurai Gourami⚠️ With cautionPeaceful · 6 cm · Hard care · 24–28 °C (75–82 °F)
- Expect GloFish Tetra to harass Samurai Gourami at times; give dense cover and watch them at feeding.
- Keep GloFish 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)
- GloFish Tetra and Three-striped Dwarf Cichlid can both be territorial; doable with space and dense planting, but watch for chasing.
- Keep GloFish 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)
- Two assertive fish, one genuinely aggressive: GloFish Tetra and Alligator Gar will hold territory and clash.
- Size gap is too large (250 vs 6 cm): Alligator Gar will treat GloFish Tetra as food.
- Alligator Gar is slow and long-finned; a busy glofish tetra shoal tends to nip at it. Keep glofish tetra in a proper group of 6+ and watch them closely.
- Your 75 L tank is below the ~3785 L this pairing really wants — crowding raises aggression.
- Keep GloFish 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)
- GloFish Tetra and Clown Knifefish are both territorial and at least one is outright aggressive — expect serious fighting.
- GloFish Tetra is bite-sized to a 90 cm predatory clown knifefish — it will be eaten.
- Your 75 L tank is below the ~750 L this pairing really wants — crowding raises aggression.
- Keep GloFish 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)
- Fire Eel (100 cm) is big enough to swallow the 6 cm GloFish Tetra whole.
- Both are a bit pushy (semi-aggressive + semi-aggressive) — workable only in a larger tank with cover and broken sight lines.
- Your 75 L tank is below the ~380 L this pairing really wants — crowding raises aggression.
- Keep GloFish 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 GloFish Tetra whole.
- GloFish 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 6+ with plenty of cover.
- Your 75 L tank is below the ~3800 L this pairing really wants — crowding raises aggression.
- Keep GloFish 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)
- Two assertive fish, one genuinely aggressive: GloFish Tetra and Redtail Catfish will hold territory and clash.
- Size gap is too large (120 vs 6 cm): Redtail Catfish will treat GloFish Tetra as food.
- Your 75 L tank is below the ~5700 L this pairing really wants — crowding raises aggression.
- Keep GloFish 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)
- Two assertive fish, one genuinely aggressive: GloFish Tetra and Spotted Gar will hold territory and clash.
- Size gap is too large (90 vs 6 cm): Spotted Gar will treat GloFish Tetra as food.
- Spotted Gar is slow and long-finned; a busy glofish tetra shoal tends to nip at it. Keep glofish tetra in a proper group of 6+ and watch them closely.
- Your 75 L tank is below the ~600 L this pairing really wants — crowding raises aggression.
- Keep GloFish 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)
- Two assertive fish, one genuinely aggressive: GloFish Tetra and Wels Catfish will hold territory and clash.
- Wels Catfish (300 cm) is big enough to swallow the 6 cm GloFish Tetra whole.
- Your 75 L tank is below the ~20000 L this pairing really wants — crowding raises aggression.
- Keep GloFish 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)
- GloFish Tetra and Wolf Cichlid are both territorial and at least one is outright aggressive — expect serious fighting.
- GloFish Tetra is bite-sized to a 72 cm predatory wolf cichlid — it will be eaten.
- GloFish 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 6+ with plenty of cover.
- Your 75 L tank is below the ~760 L this pairing really wants — crowding raises aggression.
- Keep GloFish 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.
GloFish Tetra care specs
- Care level
- Easy
- Breeding
- Hard
- Max size
- 6 cm (2.4 in)
- Min tank size
- 75 L (19.8 gal)
- Temperature
- 21–28 °C (70–82 °F)
- pH
- 6–7.5
- Hardness
- 2–15 dGH
- Lifespan
- 3–5 years
- Diet
- Omnivore
- Swim level
- Middle
- Group size
- 6+ (shoaling)
- Family
- Characidae
- Origin
- South America (Río Paraguay and Río Guaporé basins); GM stock bred in US hatcheries
What is a GloFish Tetra?
The GloFish Tetra is a genetically modified form of the black skirt tetra (Gymnocorymbus ternetzi), engineered to express a stable fluorescent protein gene derived from sea coral or jellyfish. Under standard daylight the fish looks like a vividly tinted version of the familiar black skirt tetra; under blue LED or actinic lighting the colour ignites into a neon glow. Available in electric green, starfire red, sunburst orange, moonrise pink, cosmic blue, and galactic purple, GloFish Tetras are the dominant selling point of the GloFish brand in the tetra category.
Genetics aside, every care requirement is identical to the non-modified fish. The GloFish Tetra is a hardy, mid-water shoaler that tolerates soft to moderately hard water, adapts to a wide temperature band, and handles community tanks with reasonable success — provided it is kept in a group and paired with fish that can handle a bit of exuberant fin-nipping.
Where do GloFish Tetras come from?
The underlying species, Gymnocorymbus ternetzi, originates from South America — specifically the Río Paraguay and Río Guaporé river basins in Bolivia, Brazil and Argentina. In the wild, black skirt tetras inhabit clear to dark-water streams and backwaters with moderate current, dense riparian vegetation along the banks, and a substrate of leaf litter and sand.
The commercial GloFish Tetra stock is bred entirely in US hatcheries under licence from GloFish LLC; wild-caught GloFish tetras do not exist. The fluorescent trait is stably inherited and present across all offspring, which is why GloFish can maintain brand control through that licensing model. For fishkeeping purposes, treat their native range as the environmental reference point: warm, slightly soft to neutral water with moderate flow and cover.
What size tank does a GloFish Tetra need?
The minimum recommended tank is 75 litres (20 gallons), and that figure reflects the shoaling minimum of six fish rather than the size of a single individual. A single GloFish Tetra reaches about 6 cm (2.4 in), but a group of six in tight formation needs open midwater swimming space to behave naturally and stay calm.
A standard 75 L rectangular tank (typically around 60 × 30 × 40 cm) works well. Longer tanks are preferable to tall ones — these fish swim horizontally across the mid-column and benefit from a long run rather than height. Provide some open space in the centre for shoaling and a few taller plants or driftwood pieces at the sides for structure. Blue-spectrum LED lighting will dramatically enhance the fluorescent colours.
What water parameters do GloFish Tetras need?
- Temperature: 21–28 °C (70–82 °F). The species is tolerant, though the mid-range of 24–26 °C (75–79 °F) suits most community mixes well.
- pH: 6.0–7.5. Slightly soft to neutral water mirrors the natural habitat; hard alkaline water above 7.5 should be avoided long-term.
- Hardness: 2–15 dGH — a wide band that covers most dechlorinated tap water in the UK, US and Australia without chemical adjustment.
Consistency is more important than chasing the lower end of the range. Perform weekly water changes of 20–30 %, keep the tank fully cycled before stocking, and avoid sudden temperature swings — the species handles a broad range precisely because the river systems it comes from fluctuate seasonally, but rapid changes in captivity still stress the fish and open the door to disease.
What do GloFish Tetras eat?
GloFish Tetras are omnivores that accept most commercially available aquarium foods without fuss. A good baseline is a quality tropical flake or small pellet as the daily staple, rotated two or three times a week with frozen or live foods: daphnia, brine shrimp, bloodworm and micro-worm all get taken readily. Frozen foods also tend to intensify colour saturation over time — useful given that the fluorescent effect is the main visual draw of this variety.
Feed small amounts once or twice a day, only what the fish consume within two minutes. Overfeeding is the fastest route to poor water quality in a mid-sized tank, and fouled water will dull even neon-bright tetras. Adding a few spirulina-based flakes or vegetable matter rounds out the omnivore diet, though plant material is secondary to protein in the daily rotation.
Are GloFish Tetras aggressive — and what fish can live with them?
GloFish Tetras are rated semi-aggressive, which in practice means they are active, occasionally boisterous fin-nippers — particularly when kept in a group smaller than six. In a properly sized shoal, fin-nipping energy is directed within the group during normal schooling activity and rarely escalates to injury.
The rule of thumb is straightforward: keep six or more GloFish Tetras together and choose tank mates without long, flowing fins. Long-finned bettas, angelfish, fancy guppies and similar species are frequent targets and should be avoided. Suitable community partners include peaceful, similarly sized mid- to bottom-water fish — corydoras catfish, larger rasboras, other short-finned tetras, and peaceful loaches are standard choices. Avoid very small fish (like nano rasboras under 2 cm) that may be harassed or outcompeted at feeding time.
For a full, filterable list of tested pairings, see GloFish Tetra tank mates.
How do you tell male and female GloFish Tetras apart?
Sexual dimorphism in GloFish Tetras is subtle, particularly in juveniles. In mature fish, females are noticeably deeper-bodied and rounder in the belly, especially when gravid (carrying eggs). Males are slimmer through the body and typically have a slightly broader, more squared-off anal fin compared to the female’s narrower version.
The fluorescent colouring is the same across sexes and gives no dimorphic clues — unlike some naturally coloured species where males are brighter. Because the differences are subtle, the most reliable method is to observe a group of six or more side by side: once you can compare body depth directly, the females become apparent. Single fish are genuinely difficult to sex with confidence.
How do GloFish Tetras breed?
Breeding GloFish Tetras is rated hard — not because the fish are physiologically difficult to spawn, but because of legal and practical constraints. GloFish LLC’s commercial terms prohibit intentional breeding of GloFish-branded animals for sale, so this section covers what happens in a home aquarium context where accidental or observational spawning is the likely scenario.
When conditioned with live or frozen foods and kept in soft, slightly acidic water around 25 °C (77 °F), a ripe female will scatter adhesive eggs among fine-leafed plants or spawning mops. The male pursues and fertilises as she scatters. Both parents — and any tank mates — will eat the eggs immediately, so fry survival in a community tank is effectively zero without intervention. If you observe spawning, remove adults or transfer eggs to a separate hatching container. Eggs hatch in roughly 24–36 hours; fry are free-swimming within 3–4 days and require infusoria or commercial first-foods initially.
What are common GloFish Tetra diseases?
The GloFish Tetra shares the same disease susceptibilities as the black skirt tetra and most community tetras:
- Ich (white spot): Small white grains on fins and body, caused by the parasite Ichthyophthirius multifiliis. Almost always triggered by stress or temperature drops. Prevention: stable warm water, no drastic temperature swings, quarantine new arrivals.
- Fin rot: Ragged, receding fin edges — typically a bacterial secondary infection following fin-nipping injuries or poor water quality. Prevention: adequate group size to reduce nipping, consistent water changes.
- Velvet (Oodinium): A dusty gold or rust-coloured sheen on the body. Often introduced with new fish; quarantine is the main preventive measure.
- Neon tetra disease: A progressive, incurable wasting disease caused by the microsporidian Pleistophora hyphessobryconis. Rare in black skirt tetras, but possible; the telltale sign is a pale, fading patch along the dorsal area that spreads.
In nearly every case, prevention is water quality plus quarantine. A cycled tank, regular water changes, and a four-week quarantine period for all new arrivals will head off the majority of disease outbreaks before they start.
Health note: medication dosing and disease diagnosis are beyond the scope of a care profile. Confirm symptoms against a reputable veterinary or aquatic-health source before medicating, and treat the water quality problem alongside any medication.
How long do GloFish Tetras live?
With consistent care, a GloFish Tetra lives 3–5 years. That figure is the same as the non-modified black skirt tetra, and the genetic modification does not appear to affect longevity. The key variables are water quality, diet variety, group stability, and avoiding chronic stress from incompatible tank mates or a group too small to shoal naturally. Fish kept solo or in pairs tend to be chronically stressed and rarely reach the upper end of the lifespan range.
Frequently asked questions
Are GloFish tetras the same as black skirt tetras?
Genetically, yes — GloFish tetras are black skirt tetras (*Gymnocorymbus ternetzi*) with a fluorescent protein gene added. Their care, temperament, size, and lifespan are identical to the non-modified fish. The glowing colour only shows under blue or actinic lighting.
Do GloFish tetras nip fins?
They can, especially when kept in small numbers. In a group of six or more, the fin-nipping impulse is redirected within the shoal. Avoid pairing them with long-finned tank mates — bettas, angelfish, and fancy guppies are the most common victims.
What you need to keep a glofish tetra
The baseline is a heated, filtered 75 L+ tank: a reliable heater to hold 21–28 °C (70–82 °F), a gentle filter that won't batter a glofish tetra in the current, and a tight-fitting lid. Cycle the tank fully before adding any fish.
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