Quick Stats
| Adult Size | up to 5 cm |
| Minimum Tank | 20 gal |
| Temperature | 24–28°C |
| pH Range | 5.5–7.0 |
| Hardness (GH) | 2–8 dGH |
| Difficulty | Medium |
| Temperament | Peaceful, tight schooling |
| Diet | Omnivore — flakes, micro pellets, frozen bloodworm |
| Schooling | 10+ for best display |
Tank Setup
The Rummy Nose Tetra (Hemigrammus rhodostomus) is a blackwater fish from the Amazon and Orinoco drainages — tannin-stained, soft, acidic forest streams where the tea-coloured water hides predators and concentrates fish into shimmering schools. Recreating even a mild version of that habitat is the single biggest factor in keeping this species happy: soft, slightly acidic water (pH 5.5–7.0, hardness 2–8 dGH), gentle flow, dim lighting, and a 20-gallon-long or larger tank for the constant coordinated swimming a proper school does.
Temperature sits at 24–28°C, and this is a species that genuinely prefers the warm end — unlike neon tetras (Paracheirodon innesi) it thrives at 27–28°C, which makes it one of the few tetras suitable alongside discus-style warm communities. Driftwood, Indian almond leaves, and a dark substrate both tint the water and calm the fish; sand or fine gravel works, and hardy plants (see our lighting guide for keeping plants dim and healthy) complete the look.
The famous nose is the reason this species has a reputation for being "hard": the red head flush is a live readout of water quality. In clean, soft, warm water it blazes; after a missed water change, a pH swing, or a nitrite blip it fades to pink within hours. That sensitivity is a feature — a rummy-nose school is a continuous water test that happens to be beautiful. If your tap water is hard and alkaline, blend with RO (the tap vs RO guide covers exactly how) before choosing this species.
Tank Mates
Rummy Nose Tetras are peaceful, midwater, tight-schooling fish that bother no one and are too fast and deep-bodied to be bothered by anything their own size. Their tank mate selection is really water-chemistry selection: companions must share soft, warm, acidic water, and the rest follows.
Ideal companions: Cardinal Tetras (the classic Amazon pairing, same water, same warmth), Neon Tetras at the cooler overlap, Harlequin Rasboras, and any soft-water Corydoras species like Sterbai for the floor. Dwarf cichlids are a natural match — Apistogramma share the same blackwater preferences and occupy different zones, and the Apistogramma overview lists which species suit tetra communities. Cherry shrimp (Neocaridina davidi) and Amano shrimp (Caridina multidentata) work in calm, planted versions of this tank.
Avoid boisterous or nippy species (tiger barbs, large danios in warm water push the temperature limits for both), any big cichlid that can swallow a 5 cm tetra, and aggressive feeders that will outcompete the rummy-nose's polite midwater feeding. Equally: do not keep them as a pair or trio — a school below eight fragments into nervous individuals, and it is the coordinated motion of ten-plus that makes this species worth its fussiness.
Diet & Feeding
Rummy Nose Tetras are micro-predators in the wild — insect larvae and tiny crustaceans picked from the water column — and they do best on small, frequent, protein-rich meals. Micro-pellets and quality flake form the base; frozen daphnia, baby brine shrimp, and finely chopped bloodworm bring out the red head colour and the tight schooling that goes with prime condition.
Feed twice daily, small portions — this is a midwater picker, not a gulper, and slow eaters mean surface-dwelling competitors can starve them in mixed tanks. Colour condition responds within two weeks to a carotenoid-rich frozen-food routine. They ignore sinking wafers entirely, so bottom feeders get their share without competition.
Live foods are a breeding prerequisite: a week of daily live daphnia or brine shrimp visibly deepens head colour in males and fills females with eggs. Rummy-nose wastes quickly on flake-only diets — not dying, but fading to the pale-nosed version of themselves that signals mediocre care to anyone who knows the species.
Common Health Issues
The Rummy Nose Tetra's health profile is almost entirely a water-quality profile. They are the first fish in the tank to show nitrite stress, pH shock, or chlorine damage — pale noses, then clamped fins, then white-spot. A rummy-nose that pales after a water change is telling you the dechlorinator, temperature match, or source water is wrong; the test kit guide and a liquid-based nitrite/nitrate kit are non-negotiable equipment for this species.
Ich is the most common actual disease, usually arriving with new fish or temperature swings; treat promptly and remember that heat-ramping (see our ich treatment guide) works well for tetras. The trade-name confusion matters for health too: fish sold as "rummy-nose" include the true Hemigrammus rhodostomus, the more-traded Hemigrammus bleheri (sometimes placed in Petitella), and Petitella georgiae — all similar-looking, all similar-care, but newly imported fish of any of them arrive fragile and need proper quarantine and acclimation.
Long-term failure looks like slow decline in hard, alkaline tap water: fish that never quite colour, waste over months, and fall to secondary infections. If you cannot provide soft acidic water long-term, choose a hardier tetra — the species is worth its requirements, but only if the requirements are actually met. Well-kept specimens routinely school and glow for years.
Breeding
Breeding Rummy Nose Tetras is a genuinely advanced project — not because the fish are reluctant, but because the water they spawn in is fussy: very soft (1–4 dGH), acidic (pH 5.5–6.0), warm (27–28°C), and dim. In typical hard tap water, spawning simply never triggers, which is why so few hobbyists ever see rummy-nose eggs.
Condition a group heavily on live foods, then move a full-bellied female and a best-coloured male to a dim spawning tank with fine-leafed plants or a spawning mop and peat-filtered water. Spawning happens at dawn — the pair scatters 150–300 eggs through the plants — and both parents must be removed immediately, as they are enthusiastic egg predators. Even successful spawns produce tiny, delicate fry that are among the smallest of any common tetra.
Fry need green water/infusoria for the first four or five days before graduating to microworms and baby brine shrimp; survival rates are low compared with neons or barbs. If your goal is a breeding project rather than a display, start with a group of six-plus young fish, grow them out in soft water, and cull for the strongest male/female pair — a proper breeding group makes the difference between occasional eggs and consistent production.
Frequently Asked Questions
Why is my rummy nose tetra's nose pale?
A pale nose means stress, and in this species stress almost always means water quality: ammonia or nitrite above zero, a pH swing, a recent water change with mismatched temperature or insufficient dechlorinator, or chronic hardness/alkalinity well above its 5.5–7.0 pH preference. Check the water first — the colour usually returns within a day of the cause being fixed. A fish pale for weeks in hard tap water is telling you the source water is the problem.
Which fish sold as "rummy-nose" am I actually buying?
The hobby name covers three lookalike characins: the true rummy-nose (Hemigrammus rhodostomus), the more commonly exported firehead or brilliant rummy-nose (Hemigrammus bleheri, which recent research has moved to Petitella), and the false rummy-nose (Petitella georgiae). All three share the red head and striped tail pattern and have nearly identical care. Bleheri shows more extensive red; true rhodostomus is rarer in shops. Treat them the same — soft, warm, clean water.
How many rummy nose tetras should I keep?
Eight is the practical minimum and ten to twelve is where the species becomes spectacular. Rummy-nose tetras form some of the tightest schools in the hobby — the whole group moves and turns as one — and that behaviour disappears in small groups, which fragment into shy individuals. A 20-gallon-long supports a school of ten comfortably with midwater space to spare.
Can rummy nose tetras live with discus?
Yes — it is one of the classic discus companion choices. Both species want warm (27–28°C), soft, acidic water, and rummy-nose tetras tolerate discus temperatures better than almost any other schooling tetra. Keep the school at ten-plus so the tetras stay calm, and expect them to act as dither fish that give shy discus confidence.