Rummynose tetra

Water parameters

Tolerated range for this species. Aim for the middle of each band rather than the extremes.

Tank and habitat

Substrate: any.

Behavior

Plant interaction: plant safe.

Feeding

Flake, micro pellets, frozen daphnia, bloodworm, and brine shrimp. Not fussy about food type. Feed small amounts 2-3 times daily. Rummynose tetras are midwater feeders and catch food as it drifts through the water column. Color improves with high-quality food containing carotenoids.

Compatibility

• One of the best community schooling fish. Peaceful, non-nippy, and stays in a tight group.
• Classic tankmate for angelfish, discus, rams, and other South American community fish. The tight schooling behavior is visually spectacular with these centerpiece fish.
• Works with corys, plecos, small gouramis, and other tetras.
• Avoid very aggressive tankmates. Rummynose tetras are not easily stressed but they lose their red coloration when harassed, which defeats the purpose of keeping them.
• Safe with shrimp and snails.

Origin and habitat

Rummynose tetra is a name shared by three closely related characins, all reclassified into the genus Petitella in 2020 after a molecular study. The one usually meant, and the most common in the trade, is Petitella bleheri, the firehead or brilliant rummynose, which carries the most extensive red, spilling past the gill cover onto the front of the body; it comes from the middle Rio Negro and the upper and middle Orinoco across Brazil, Colombia, and Venezuela. The other two are Petitella rhodostoma, the original or Ahl's rummynose from the lower Amazon, and Petitella georgiae, the false rummynose from western Amazon whitewaters. All three live in soft, acidic blackwater forest creeks among leaf litter and dim light. The brilliant red nose doubles as a living water-quality gauge: it blazes when the fish is healthy and settled and fades to pale pink under stress or poor water, which is part of why the species is so prized. They form some of the tightest, most coordinated schools of any aquarium fish and look best in groups of ten or more. P. bleheri stays around 5 cm, while the other two run a little larger. Platinum, albino, and golden strains of P. bleheri are bred for the trade.

Breeding

Breeding is difficult, more so than most tetras. It calls for very soft, acidic water, below about pH 6 with almost no hardness, often with peat filtration, dim light, and warmth around 28 C. A conditioned mixed group spawns at first light, scattering light-sensitive eggs among fine plants; the adults eat the eggs, so a mesh false bottom or thick moss helps, and the parents come out afterward. Eggs hatch in roughly a day to a day and a half, and the fry need infusoria-grade food at first. Because the requirements are exacting, much of the trade is still wild-caught from Brazil.

Common problems

The fading nose is the most-asked-about thing and the most useful: a pale nose means something is off, whether ammonia, nitrite, a temperature swing, or harassment, while a vivid red that runs well past the eye signals a healthy, settled fish. Newly bought rummynose almost always arrive pale from transport and colour up within days once conditions are good. They like warm, stable water and dislike swings, and ich is the usual ailment on stressed new arrivals. Otherwise, kept in a decent school in soft, clean water, they are reliable and striking.

Bioload

Further reading

• Why your angelfish ate your neons
• Blackwater tanks: replicating acidic jungle streams
• The schooling number matters more than you think