From Venezuela we recently received „feather tetras“. This is what we used to call tetras that have a striking black stripe in the anal fin, accompanied by a white line in front of it. In general, however, the term “feather tetra” is alternatively used to species of the genus Hemiodus or Hyphessobrycon copelandi. Our “feather tetra” was first identified by us as Hemigrammus unilineatus.
Hemigrammus unilineatus is the type species of the genus Hemigrammus. It has a double, namely Moenkhausia hemigrammoides. The only externally visible difference between these two species is the lateral line, i.e. the sensory organ running over the flanks of the fish. In Hemigrammus this sideline runs over half the body length (Hemi: half, grammus: drawn), in Moenkhausia it runs over the whole body length. This feature can be seen on sharp photos.
Until recently, Moenkhausia hemigrammoides was thought to occur only in the Guyana countries, while Hemigrammus unilineatus occurs there and also in large parts of Brazil, Venezuela, Colombia and Bolivia; this explains why we first called our new imports H. unilineatus without much thought. But now we found the time to take a closer look at them and lo and behold: they have a complete lateral line, so it must be Moenkhausia hemigrammoides!
By chance, a study has just been published – in September 2019 – which for the first time describes the occurrence of M. hemigrammoides in Colombia (rivers Ariari and Inirida, both tributaries to the Rio Guaviare in the upper Orinoco basin), which makes the occurrence of the species in Venezuela very likely.
Moenkhausia hemigrammoides are very lively fish that constantly play with each other and rush through the aquarium in lightning-fast turns. The fish grow to about 4 cm in length (in nature the size of adult animals is between 2.1 and 3.3 cm, measured without caudal fin) and are therefore a real enrichment of the aquarium, even if they are not very conspicuous in colour.
For our customers: the animals have code 268653 on our stocklist. Please note that we only supply the wholesale trade.
Text & photos: Frank Schäfer
Literature:
Géry, J.(1965): Notes on characoid fishes collected in Surinam by Mr. HP Pijpers, with descriptions of new forms. Bijdragen tot de Dierkunde 35 (1): 101–126.
Méndez-López, A. & A. Urbano-Bonilla (2019): Moenkhausia hemigrammoides Géry, 1965 (Characidae, Stethaprioninae) in Colombia: new records and comments on morphology. Check List 15 (5): 867-874
