The rummynose tetra is a slender silver shoaling characin instantly recognised by its blood-red head and the bold black-and-white striped tail. It is one of the tightest-schooling aquarium fish, making a synchronised group a centrepiece of planted blackwater-style community tanks. The intensity of the red 'nose' is a reliable indicator of water quality and fish health, so this is a slightly demanding fish best suited to a stable, mature aquarium.
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Lower Amazon basin, South America (Brazil, around the Rio Negro and Pará region)
Origin
New World
Climate
🌴 Tropical
Water type
💧 Freshwater
Family
Characidae
Genus
Hemigrammus
Part of the Tetras
Small, often brightly colored characin fishes popular as peaceful shoaling community aquarium fish. Tetras are kept in groups, appreciate soft, slightly acidic water and planted tanks, and range from tiny nano species to larger schooling fish.
From the minimum an animal needs to be kept humanely, up to the ideal setup. Bigger is almost always better — minimums are floors, not targets.
Photo coming soon
Minimum
Soft-water school tank
20 gal long / 75 L (school of 6+)
Hemigrammus rhodostomus needs soft acidic water (pH 5.5–7.0, 24–28 °C), mature filtration, and a school of 6+. The red nose fades or whitens with stress/poor params.
Photo coming soon
Recommended
Planted blackwater community
29–40 gal / 110–150 L
Long footprint for a tight school of 10–15. Driftwood, leaf litter, and dim light bring out the crimson nose and tight schooling formation.
Photo coming soon
Ideal
Amazonian biotope
55 gal+ / 200 L+ biotope
Large blackwater biotope with school of 20+, RO-buffered water, and constant tannins. Tightest schooling display in the hobby — moves as one organism.
Life & growth stages
How this animal changes through its life — each stage often has its own care, diet and space needs.
Photo coming soon
Egg
Fish eggs are small, translucent spheres, often laid in clutches on plants, substrate, or in a nest — or carried/brooded by a parent in livebearing and mouth-brooding species. A dark eye spot and the curled embryo become visible inside as development progresses.
Photo coming soon
Fry
Newly hatched fry are tiny and semi-transparent, frequently still carrying a yolk sac that fuels them before they feed freely. They lack full fin structure and adult coloration, staying near cover until they can swim and forage on their own.
Photo coming soon
Juvenile
Juveniles look like miniature adults but with developing fins and muted or different markings; many species shift pattern and color as they mature. Growth is rapid at this stage given clean water and steady feeding.
Adult
Adults show the species' full size, finnage, and mature coloration, and are sexually mature. Many fish develop sex-specific differences in size, color, or fin shape, which can intensify during breeding.
Habitat & enclosure
Keep a shoal of at least 6-8 (ideally 10+) in a tank of 75 litres (20 gal) or larger with plenty of swimming length. Target soft, slightly acidic blackwater conditions: temperature 24-27 °C (75-81 °F), pH 5.5-6.8, soft to moderately soft water (GH 2-8). Provide gentle to moderate flow and subdued lighting broken up by floating plants; dark, tannin-stained water deepens colour and security.
This species is sensitive to swings in pH, hardness and nitrate, and a faded or pale red head is an early warning of deteriorating water. Only add it to a well-cycled, established tank and keep nitrates low with regular water changes.
Substrate
Dark fine sand or fine gravel best shows off the silver body and red head. A scattering of leaf litter (Indian almond/catappa, oak) and driftwood releases tannins for a natural blackwater aquascape.
Equipment & setup
A gentle filter (sponge or well-baffled hang-on-back/canister) keeps flow moderate, and a reliable heater holds the tropical temperature. Subdued LED lighting with floating cover plants suits this fish; no CO2 is required unless the planted layout demands it.
Diet
Micropredatory omnivore. Offer a varied diet of high-quality micro-pellets and crushed flake supplemented with small live and frozen foods such as daphnia, cyclops, baby brine shrimp and microworm. A varied, protein-rich diet intensifies the red coloration.
Behavior & temperament
Peaceful, active mid-water shoaler that must be kept in groups; isolated individuals become stressed and lose colour. An excellent community fish that mixes well with other small peaceful species such as other tetras, rasboras, pencilfish, Corydoras, dwarf cichlids and small loaches. Avoid large or aggressive tankmates and fin-nippers.
Health
Susceptible to ich (white spot) and other stress-related infections when water quality is poor or parameters fluctuate. Watch for fading of the red head as a non-specific health/water-quality signal. Quarantine new stock; wild and wild-type imports can carry parasites and are sensitive during acclimation.
Tips, DIY & hacks
Drip-acclimate slowly and add to a mature tank only, as this is one of the less forgiving 'easy' tetras. Adding catappa (Indian almond) leaves and peat-filtered or RO-remineralised water both colours the water and brings out the brightest red. Buy the largest healthy group you can to encourage tight, confident schooling.
