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title: "Rummynose Tetra: The Complete Care, Tank & Breeding Guide" description: "The definitive rummynose tetra (Hemigrammus rhodostomus) care guide: soft water parameters, the red nose as a water-quality gauge, tight schooling, tank setup, and breeding." slug: rummynose-tetra commonName: Rummynose Tetra scientificName: Hemigrammus rhodostomus family: Characidae order: Characiformes difficulty: Intermediate minTankSize: 20 temperature: "75–82°F (24–28°C)" ph: "5.5–7.0" hardness: "1–8 dGH" lifespan: "5–6 years" maxSize: "2 inches (5 cm)" origin: "Brazil — lower Amazon" publishedAt: "2026-06-04"

Rummynose Tetra: The Complete Care, Tank & Breeding Guide

The rummynose tetra is the synchronised-swimming champion of the freshwater hobby — the tightest-schooling of all common tetras, a silver torpedo with a blazing red nose and a black-and-white striped tail, that moves with its shoalmates as if they shared a single mind. Hemigrammus rhodostomus offers two things no other tetra matches: the most mesmerising group behaviour in the hobby, and a built-in health gauge, because that famous red nose fades the moment water quality drops or the fish is stressed. It's a living test kit and a breathtaking centerpiece in one.

This guide is the complete reference: the rummynose's blackwater biology, the soft water it needs, why the red nose indicates water quality, how to set up its tank, what to feed it, which tank mates suit it, and how to breed it.

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Species Overview

The rummynose tetra (Hemigrammus rhodostomus) is a small characin from the lower Amazon, reaching about 5 cm (2 inches). Its body is a clean, silvery torpedo, capped by a brilliant deep-red nose and face, and finished with a striking black-and-white horizontally striped tail. (Two similar species — the "true" rummynose, the false rummynose Petitella, and the firehead tetra Hemigrammus bleheri — are all sold as "rummynose" and cared for identically; H. bleheri often has the most extensive red.)

The rummynose is famous for two traits. First, it is the tightest-schooling common tetra, forming a dense, coordinated shoal that moves and turns in near-perfect unison — the finest schooling display in the freshwater hobby. Second, its red nose is a water-quality indicator: vivid red signals a healthy fish in good water, while a faded or pinkish nose warns of stress, poor water, or improper acclimation. Rummynoses are peaceful and shoaling, rated intermediate for their need for soft, warm, clean, stable water and a mature tank. With good care they live 5–6 years.

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Natural History and Origin

Hemigrammus rhodostomus lives in the soft, acidic, often tannin-stained blackwater of the lower Amazon basin — slow, dark, mineral-poor forest waters shaded by vegetation and stained by leaf litter. Like the cardinal tetra, it is a soft-water blackwater specialist, which is why it needs soft, acidic, warm conditions and a stable, mature tank rather than hard or fluctuating water.

In the wild, rummynoses form large, tightly-coordinated shoals over leaf litter and submerged structure, feeding on tiny invertebrates — the dense schooling is an anti-predator strategy that they retain strongly in the aquarium, far more so than most tetras. Their red nose's sensitivity to water conditions reflects how attuned these blackwater fish are to clean, stable, soft water; it's an honest signal of the fish's physiological state, which is what makes it such a useful gauge for keepers.

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Water Parameters — and the Red-Nose Gauge

Rummynoses need soft, warm, acidic, very clean, stable water in a mature tank. Their standout feature for keepers is the red nose as a built-in gauge: a bright red nose means the fish is healthy and the water is good; a pale or pinkish nose signals a problem — high nitrate, ammonia, instability, a new tank, or stress from poor acclimation. Treat a fading shoal as a prompt to test and improve your water. Confirm cycling with the nitrogen cycle tracker, dial in soft water with the GH/KH converter, and keep parameters in range with the water parameters reference. Never add rummynoses to a new or hard-water tank.

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Tank Setup Guide

Tank size

A proper shoal needs a minimum of 20 gallons (75 litres), with 29+ gallons better, and length matters — rummynoses are active swimmers that need horizontal room to perform their coordinated schooling. Always keep them in a group of at least 8, ideally 10+, for the full effect.

Aquascape — open water plus blackwater feel

Rummynoses want open swimming space for their shoaling, framed by a planted blackwater aquascape: a dark substrate, driftwood, leaf litter and botanicals (for gentle tannins and lower pH), and background/side planting like Java moss, leaving the central water column clear for the shoal to cruise. Subdued lighting (or floating plants like duckweed) keeps them secure and shows their colours and the crisp tail stripes.

Filtration, flow, lighting

Rummynoses appreciate moderate flow (more than most blackwater tetras — they're strong swimmers that often school into a gentle current), good filtration, and subdued lighting. A mature, soft, clean, stable tank is essential for keeping their noses red and their behaviour confident.

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Feeding Guide

Rummynose tetras are micro-predators that take small foods readily.

What to feed

• High-quality micro-pellets and crushed flake — a convenient staple.
• Live and frozen daphnia and baby brine shrimp — relished, excellent for colour and condition.
• Cyclops, microworms, and small frozen foods for variety.

How often

Feed two to three small meals daily. A varied diet keeps the fish in good condition and the nose vividly red. A healthy rummynose shoal feeds eagerly and tightly together. Note that a faded nose during stress or poor water may also coincide with reduced feeding — another signal to check conditions.

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Behavior and Temperament

The rummynose tetra's behaviour is its glory: it is the tightest-schooling common tetra, forming a dense, beautifully coordinated shoal that wheels and turns in near-perfect unison, especially in a current or when alarmed. A group of 10 or more produces the single best schooling display in the freshwater hobby — reason enough to keep them. In small numbers, however, they become nervous, scattered, and pale, so a proper shoal is essential, not optional.

They are completely peaceful toward other species and make superb dither fish. Being soft-water blackwater fish, they're somewhat more sensitive than hardy community tetras and show stress readily (via the nose and via loose, jittery schooling), which is part of what makes them such an honest indicator of tank conditions. Given a mature, soft, clean, stable tank and a good-sized group, rummynoses are confident, active, and endlessly watchable.

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Compatibility

Rummynose tetras suit a peaceful, soft-water community of fish that share their conditions and won't eat them.

Good tank mates: cardinal tetra, neon tetra, ember tetra, harlequin rasbora, corydoras, otocinclus, german blue ram, bolivian ram, bristlenose pleco, and discus (they share warm, soft water and are a classic discus dither fish).

Cautions:

• Angelfish and larger cichlids — may eat small tetras.
• Any fish large enough to eat them — rummynoses are bite-sized.
• Boisterous or fin-nipping fish — stress the shoal and disrupt schooling.

A rummynose shoal is a classic dither fish for discus and dwarf cichlids in a soft-water community. Use the compatibility checker to plan.

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Breeding Guide

Breeding rummynose tetras is challenging and a project for experienced soft-water keepers. They are egg-scatterers that require very soft, acidic water (low GH, pH well below 7) to produce fertile eggs, along with dim conditions, mirroring their demanding blackwater origins.

Condition a group on rich live foods, then set up a separate, dimly-lit breeding tank with very soft, acidic water and fine-leaved plants or a spawning mop. The pair scatters eggs among the plants; the eggs and fry are light-sensitive, so keep the breeding tank dark. Remove the adults after spawning, as they eat the eggs. The tiny fry need the smallest first foods — infusoria, then microworms and baby brine shrimp — in pristine, soft, dark water. The strict water-chemistry requirements make this a more advanced spawn than hardier tetras, but a rewarding one for dedicated breeders.

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Health and Disease

Rummynose tetras are hardy in correct water, with most problems traced to hard water, immature tanks, stress, or shipping — and conveniently flagged early by the fading nose.

Stress and "wrong water" decline are the main issues — rummynoses in hard, alkaline, or unstable water lose their red nose, school loosely, and waste away. Ich can follow temperature swings, especially in newly added fish. Neon tetra disease (Pleistophora) can affect them, as with other small characins; there's no cure, so quarantine and good conditions are key. Bacterial infections strike stressed fish.

Prevention: a mature, soft, acidic, warm, clean, stable tank; a good-sized shoal; careful acclimation and quarantine; and a varied diet. Watch the nose as your early-warning system — a fading shoal is telling you to check the water before real trouble develops. Given proper soft-water conditions, rummynoses are robust, long-lived fish.

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Interesting Facts

• A living test kit. The red nose fades with stress or declining water quality and glows when all is well — an honest, real-time gauge of tank conditions.
• The tightest schoolers. No common tetra schools as densely or as coordinated as the rummynose, making it the gold standard for schooling displays.
• Three "rummynoses." The true rummynose, the false rummynose (Petitella), and the firehead tetra (Hemigrammus bleheri) are all sold under the name and cared for identically.
• A discus classic. Their warm soft-water needs and tight schooling make them the traditional dither fish for discus tanks.
• Blackwater natives. Like cardinals, they come from soft, acidic, tannin-stained Amazon water — the key to their care.

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Bringing It Together

The rummynose tetra offers two things no other fish quite matches: the most mesmerising tight-schooling display in the freshwater hobby, and a built-in water-quality gauge in the form of its vivid red nose. Give it a mature, soft, warm, acidic, very clean, stable tank with open swimming space framed by a planted blackwater scape, moderate flow, subdued light, a varied diet of small foods, and peaceful soft-water tank mates — and keep a shoal of 10 or more — and it will wheel through your tank in breathtaking unison for years, its glowing red noses confirming all is well. It's the classic dither fish for discus and dwarf cichlids like the german blue ram, and a perfect shoalmate for cardinal tetras. Plan the build with the AI Tank Blueprint generator and dial in soft water with the GH/KH converter.