Brilliant rummy-nose tetra

1) Where they come from

Rummy-nose tetras (Hemigrammus bleheri) come from the Amazon basin—think warm, tannin-stained streams and flooded forest edges. A lot of the ones we buy are bred on farms now, but they still “act” like fish from soft, slightly acidic water.

2) Setting up their tank

Give them swimming space more than decorations. They’re a tight-schooling fish and they look best when they can do their synchronized “one fish mind” thing across the front of the tank.

• Tank size: 20 long works for a proper group, but 29–40 breeder is where they really start to look amazing
• Group size: 10+ if you can swing it (6 is the bare minimum, but they’re way bolder in bigger numbers)
• Filtration: steady, not blasting—think gentle current rather than river rapids
• Lighting: they don’t need it bright; plants + dimmer light makes them calmer
• Decor: wood, leaf litter vibe, plants around the edges, open center lane for schooling

They’re not a “set and forget” tetra. They like clean water and they show it fast when things slide. I keep mine on a simple routine: weekly water changes and don’t let gunk build up in the substrate.

3) What to feed them

They’re easy to feed once they settle in, but a brand-new group can be a little shy for the first few days. Small foods work best—tiny mouths, fast metabolisms.

• Staple: a good micro pellet or fine flake (crush it if needed)
• Color/conditioning: frozen baby brine shrimp, daphnia, cyclops
• Treats: live baby brine if you have it—gets them schooling and hunting
• Schedule: small amounts 1–2x/day; they do better with “snacks” than one big dump

4) Behavior and tankmates

Rummy-nose are peaceful, tight-schooling, and honestly one of the best “movement fish” you can add. They don’t usually nip fins, and they spend most of their time midwater, cruising as a group.

• Great tankmates: other calm tetras, Corydoras, small rasboras, pencilfish, otos, peaceful dwarf cichlids (like rams), and most community-friendly shrimp (adult shrimp usually fine)
• Use caution with: big/boisterous fish, fast feeders that outcompete them, and anything nippy
• Avoid: fin-nippers (many barbs), aggressive cichlids, and larger predators that see “tiny tetra school” as a buffet

They’re also a nice “health bar” for the whole tank. If the school gets loose, colors fade, or they start hovering in corners, I take that as a sign to check temperature, ammonia/nitrite, and do a water change.

5) Breeding tips (if you want to try it)

Breeding rummy-nose tetras is doable, but it’s one of those projects where the setup matters more than luck. They’re egg scatterers and the adults will absolutely snack on the eggs if given a chance.

• Use a separate breeding tank (10–20g) with a sponge filter
• Go soft and slightly acidic if you can (this is where RO or cut RO water helps)
• Add a spawning mop or a thick clump of fine plants (Java moss works), or a mesh/egg crate so eggs fall out of reach
• Condition the adults with frozen/live foods for a week or two
• Dim the lights; many people get best results with early-morning spawning

If you see spawning (chasing and quivering in plants/mop), pull the adults after. Fry are tiny—think infusoria/rotifers first, then baby brine shrimp once they’re big enough.

6) Common problems to watch for

Most rummy-nose issues I’ve seen come down to stress from shipping + not-great water quality. They’re hardy once settled, but they can look rough fast if something’s off.

• Pale nose / washed-out colors: often stress, cold water, or rising nitrogen waste—test and do a water change
• Hanging at the surface or gasping: low oxygen, high temp, or a cycle problem—add aeration and check parameters
• White spots (ich): shows up easily after a temperature swing or new fish—quarantine new arrivals if you can
• Skinny fish that won’t fill out: parasites are possible; also check that they’re actually getting food in a busy community
• Sudden losses after purchase: acclimation/shipping stress—keep lights low, feed lightly, and don’t chase perfect numbers on day one