Helogenes marmoratus  Günther, 1863   

A little bit of history on this species and three others in the Helogenes genera, H. castaneus (from the Rio Meta basin, Colombia) H. gouldingi, (from the Rio Madeira basin, Brazil) and H. uruyensis from southern Venezuela. They were all in the previously named Helogenidae family but were incorporated into the Cetopsidae family in 1995 and consequently in the sub-family Helogeninae. H. marmoratus although scarce in the hobby seems to be the only one out of the four species that is sometimes exported from the trade.

When Günther described H. marmoratus in 1863 he placed it in the Hypophthalmidae and it was not until 45 years later that Eigenmann on its second collection that he removed Helegenes from Hypophthalmidae and described a new family for it, the Helogeneidae. The species remained monotypic for a further nearly 80 years until Delsman described a second species, H. amazonae based on a single species caught in the vicinity of Manaus, Brazil, this turned out later to be a synonym of H. marmoratus. Another species was named by Dahl in 1960 and naming it Leyvaichthys castaneus. This later was renamed Helegens castaneus and the main discription was the lack of an adipose fin, hence the new genus name. This variability within the Helogenidae concerning the adipose fin which ranged from the Peruvian populations from relatively small, through very small, to being totally absent and this absence of the fin had been used to distinguish, wholly or in part, the genus Leyvaichthys from Helegenes.

The possession of nine principal fin rays in the lower lobe of the caudal fin of Helogenes marmoratus distinguishes it from H. gouldingi and H. castaneus, which have eight principal rays on the lower lobe of that fin. The 39-48 anal-fin rays of H. marmoratus separates that species from H. uruyensis, which has 32-37 anal-fin rays.

H. marmoratus is a typical inhabitant of black or clear waters, and is usually found in forest streams with a moderate to swift current flow over firm sand or gravel bottoms. Lives hidden under plants, litter or plant debris. Can easily be mistaken as a piece of dead wood when it rests on its side, and lies motionless on the bottom. Often swims on one side in undulating movements.

This is a catfish that likes the upper levels of the aquarium. It likes to hide in plants/vegetation at the surface so either floating plants or long strands of Valisineria plants would work better as they will be unhappy in a bare unplanted tank. This trait can be seen in the upper image.

Helogenes: Helos = marsh; genus = born.
marmoratus: Marbled; mottled.

Dorsal: The primary rayed fin(s) on top of the body

Caudal fin: The tail.

Anal fin: The median, unpaired, ventrally located fin that lies behind the anus, usually on the posterior half of the fish.
Pectoral fin: The paired fins just behind the head.

Ventral Fin: The paired fins, between the pectorals and the anal fins.
Adipose fin: Fleshy finlike projection without rays, behind the rayed dorsal fin.
Maxillary barbels: Pertaining to the upper jaw. (maxillary barbels)