Rummy-nose tetra

The rummy-nose tetra (Hemigrammus rhodostomus) is a classic South American characin cherished by aquarists for its vivid red head and boldly banded caudal fin pattern. It inhabits blackwater rivers and tributaries of the Rio Orinoco and lower Amazon basins in Venezuela and Brazil, where the water is stained brown by tannins and highly acidic. Reaching a maximum of 5 cm, this is a tightly shoaling species that must be kept in groups of at least 10 to feel secure and display natural behaviour — solitary specimens or small groups quickly become stressed and lose their vibrant coloration. The tank should ideally be at least 90 cm in length to accommodate their active swimming style. A biotope setup with river sand, driftwood branches, and dried leaf litter brings out the best in these fish, though they also thrive in well-planted conventional aquaria. The rummy-nose is renowned as an "indicator fish": its red head fades noticeably when water quality deteriorates or conditions are stressful, making it an excellent early-warning system for the aquarist. An omnivore, it accepts all small foods but benefits from a varied diet of dried flakes, granules, and small live or frozen fare to maintain peak colour. It is entirely peaceful and makes an ideal dither fish for Apistogramma dwarf cichlid communities or discus tanks.