Bernat Arlandis · CC BY-SA 2.0 — Wikimedia Commons (cropped)
Rummy-nose Tetra
Hemigrammus rhodostomus
The tightest schooler in the hobby, with a built-in stress gaugeIntermediate
- Lifespan
- 5-6 years
- Size
- 5cm
- Social needs
- Tight schooler; keep 10+ together
- Time
- 10-15 min daily; weekly water change
- Cost
- Low-Medium
- Diet
- Omnivore (micro-pellet, flake, frozen foods)
Overview
What is this animal?
- Rummy-nose tetras are silver torpedoes with a glowing red face and a boldly striped tail, famous for schooling more tightly than almost any other aquarium fish.
- A group moving as one is a genuine spectacle.
- They carry a built-in diagnostic: the red nose drains to washed-out pink when the fish are stressed or the water deteriorates, making the school a live water-quality gauge.
Temperament
- Completely peaceful, rummy-noses spend the day cruising in formation through the lower midwater.
- The tighter the school, the more secure the fish — small groups huddle and hide instead.
- They are ideal companions for other gentle blackwater species: cardinal tetras, corydoras, dwarf cichlids, and pencilfish.
- Nothing about them threatens shrimp colonies beyond the odd newborn.
A good fit for
- Keepers who want true, dramatic schooling behaviour
- Mature planted aquariums with stable parameters
- Communities with dwarf cichlids and corydoras
- Aquarists who like visible feedback on water quality
Common mistakes to avoid
- Adding them to brand-new, unstable tanks
- Groups under 8-10 that huddle rather than school
- Temperature and parameter swings — noses fade fast
- Buying freshly imported, unrested stock
Enclosure
Minimum 75 litres (20 US gallons) — for a group of 10
Cannot be kept alone. The minimum is 10, and the space above is for that group.
- Keep a school of ten or more in a mature, cycled aquarium of 75 litres (20 gallons) or larger — bigger groups in longer tanks school more impressively.
- Provide open swimming length with planted flanks.
- Hold the temperature at 24-28C.
- They come from soft, acidic blackwater, and while tank-bred stock adapts to moderately hard water, what they cannot forgive is instability: drift and spikes show in the noses immediately.
Supplies
Setup
- Tank and stand
- Filter
- Heater and thermometer
- Substrate, plants and decor
- Liquid test kit
- Dechlorinator and starter supplies
Ongoing
- Micro-pellet or finely crushed tropical flake
- Frozen daphnia and cyclops
- Frozen or live baby brine shrimp
- Microworm culture (optional, for fry and conditioning)
- Spirulina-based flake
- Fine net for removing leftovers
- Small feeding spoon for accurate pinches
Safe substrate: Inert aquarium gravel · Fine, smooth sand · Aquasoil for planted tanks
Care routine
Daily
- Check temperature and equipment
- Feed
- Head-count and look everyone over
Weekly
- Top up evaporationevery 3 days
- Clean glass and clear algae
- Count the school
- Test the water
- Water change and gravel vacuum
Monthly
- Trim and thin the plantsevery 2 weeks
- Check supplies and reagent dates
- Rinse the filter media
Less often
- Replace chemical filter media (Carbon/Purigen)every 2 months
Vet: Quarterly school and stability review — every 3 months
Top resources for more info
Independent creators and organisations we would send a friend to. We have no affiliation with any of them, and nothing here is sponsored. Links checked 2026-09-19.
YouTubers
Sites
Go deeper
Diet
- Offer fine flake or micro-pellets as the staple, with regular frozen or live treats such as daphnia, cyclops, baby brine shrimp, and chopped bloodworm.
- Their mouths are small, so size food accordingly.
- Feed once or twice daily in small amounts.
- A well-fed, settled school shows saturated red noses at every feed.
Health
- Rummy-noses are not delicate once settled, but they ship poorly and resent new, unstable tanks; add them to mature aquariums only and quarantine first.
- Losses in the first fortnight usually mean the tank, not the fish, was not ready.
- After that, standard tetra care applies: watch for ich after temperature dips and keep nitrate low with steady weekly water changes.
- Faded noses are the early-warning sign — investigate before anything else goes wrong.
Is your enclosure big enough?
Is this urgent?
In a fish tank the patient is usually the water. Test before you treat — dosing a healthy tank for a disease it does not have makes things worse.
Go now
Today
Soon
Never add a new fish to a tank that is not fully cycled, and never treat blind. A test kit is cheaper than the fish.
This is general guidance for a healthy adult, not a diagnosis. An exotics vet who knows your animal always overrides it — and the time to find one is before you need one.
What it really costs
Setup, monthly, first year and across a whole life, itemised and with the electricity worked out from the actual wattage. Published figures for the same animal disagree by a factor of four, so the calculator shows ranges rather than picking one.
Bedding and substrate
Substrate in an aquarium is a filter as much as a floor. Most of the biology lives in and on it.
Safe
With a caveat
Never
This is our general list for freshwater fish. We have not built one specific to Tetras yet.
My kit says 0.25 ppm. Is that dangerous?
A liquid kit measures total ammonia, but only the un-ionised fraction is really toxic, and that fraction is governed by pH and temperature — each whole pH unit multiplies it roughly tenfold. So the same reading can be nearly harmless in one tank and lethal in another; this works out which one you are in.
Compare with other animals
The same axes for every animal, side by side — the way the guides are written makes that a fair comparison rather than two articles.
Tetras, side by side
Same axes, same care guides — the honest way to choose between types.
See all Tetras side by side →
