Hemigrammus rhodostomus

Rummy Nose Tetra

14/04/2021 Off By Andy Ptyushkin

The Rummy Nose Tetra (Hemigrammus rhodostomus) is a species of tropical freshwater characin fish originating in South America, popular among fishkeepers as an aquarium fish. One of many small tetras belonging to the same genus, it is on average 2 in long when fully grown, and is a long-established favourite among tropical fish keepers.

The Rummy Nose Tetra is fusiform in shape, whose basal body colour is a translucent silvery colour suffused in some specimens with a greenish tint: iridescent green scales are frequently seen adorning the fish at the point where the fontanel meets the body. The fins are hyaline, with the exception of the caudal fin. This fin is adorned with black and white horizontal stripes, variable in number, but usually comprising one central black stripe in the central portion of the tail fin, with two horizontal black stripes upon each caudal-fin lobe, the spaces between the stripes being white, the total count of black stripes being five. The head is a deep red colour, iridescent in lustre, with the red continuing into the iris of the eye, and some red colouration extends beyond the operculum into the anterior-most section of the body proper. Some specimens classified as Hemigrammus rhodostomus possess three blacktail stripes instead of five, and some specimens classified as Petitella georgiae have a black stripe in the caudal peduncle extending forwards into the body, surmounted above by a thin iridescent gold line: however, whether these features are reliable determinants of species identity has yet to be fully ascertained.

Male and female individuals exhibit no obvious visual differences, other than increased fullness of the body outline in ripe females.

Distribution: Brazil and Venezuela, in the lower Amazon basin in Pará State and Orinoco River.

Lower Amazon Basin

Lower Amazon Basin

The fish is interesting in that it can act as a «mine canary» in an aquarium, alerting the aquarist to potential pollution problems in an aquarium. When levels of certain metabolic wastes (ammonia, nitrites and nitrates) exceed critical levels, the intense ruby-red colour of the fish’s facial area becomes pale. The fishes also become pale in appearance immediately after the disturbance that takes place in the aquarium following a water change, but in this instance, once clean water has been supplied the intense deep red colour returns. Persistent paleness of the head is to be taken as a sign that water chemistry parameters in the maintenance aquarium are in need of adjustment, and that pollutant levels are becoming dangerous for the inhabitants.

Lifespan for the Rummy Nose Tetra in the aquarium is usually 5 to 6 years with careful maintenance. Exceptional specimens can live for more than 8 years.

Feeding presents relatively few problems, as the fishes will eagerly devour a range of prepared as well as live fish foods. In common with numerous other tetras, these fishes are particularly fond of Live Bloodworms (these are the aquatic larvae of a midge belonging to the genus Chironomus) and will also devour Live Daphnia avidly. Unlike those tetra species which adapt to surface feeding in the aquarium, rummy-nose tetras are not considered likely to add live mosquito larvae to their diet in the aquarium, though instances, where these fishes discover and enjoy this food, are possible: usually, Rummy Nose Tetras prefer to take their foods in the middle and lower regions of the aquarium.