Petitella

This is one of three species commonly sold under the name "rummy-nose tetra". The commonest of these is the firehead tetra, Hemigrammus bleheri, whilst the "true" rummy-nose is Hemigrammus rhodostomus. All three are very similar in appearance, but can be distinguished by several factors. The first is by the extent to which the red colouration on the head of the fish extends into the body. H. bleheri is the only one of the 3 in which the red extends beyond the gill covers. ...