Hampala bimaculata

Hampala: from a Javanese vernacular name for this genus.

bimaculata: from the Latin bis, meaning 'two', and maculato, meaning 'spotted', in reference to this species' distinctive colour pattern comprising two vertical blotches on the flanks, one under the dorsal-fin and another on the caudal peduncle.

Endemic to Borneo with records from the Malaysian states of Sarawak and Sabah, Indonesian province of East Kalimantan (Kalimantan Timur), and Brunei Darussalam.

Type locality is 'Indonesia: Borneo: Kalimantan Timur: Howong [about 0°15'N 115°30'E], Bo and Kajan Rivers'.

Predominantly a riverine fish preferring clear, well-oxygenated, running waters with substrates of sand, gravel, rock or mud, typically flowing through tropical forest.

In the habitat seen in our images sympatric fish species included Barbonymus balleroides, B. collingwoodi, Cyclocheilichthys repasson, C. apogon, Diplocheilichthys pleurotaenia, Garra borneensis, Leptobarbus hosii, and an unidentified Gastromyzon sp.

This species is poorly known in the ornamental trade and its adult size more-or-less precludes its suitability as an aquarium fish.

The genus Hampala currently contains seven species of which H. macrolepidota and, to a lesser extent, H. dispar are the only ones seen with any regularity in the aquarium trade. As well as being the more widely-distributed in nature, H. macrolepidota is also the largest of the group. All representatives can appear superficially similar at first glance, the exception being H. lopezi which is endemic to a single island in The Philippines and displays a unique lateral band-like marking on the flanks.

H. macrolepidota is easy to identify by colour pattern, which comprises a dark vertical band originating anterior to the dorsal-fin and extending below the lateral line, plus the presence of black marginal stripes in both lobes of the caudal-fin. H. dispar possesses only a single dark blotch-like marking on the body and has less well-defined marginal stripes on the caudal lobes.

Juveniles of the two species can appear very similar as the body blotch is extended vertically in young H. dispar, plus both display a broadish dark band across the caudal peduncle, a second, thinner band across the base of the caudal-fin, and a small blotch above the anal-fin. All of these markings are less intense in H. dispar while in H. macrolepidota there is additional dark patterning above and below the eye and running downwards from the nape to the pelvic fins.

H. sabana also has a single body marking but a higher count of circumpeduncular scales (30-32) and relatively few lateral line scales (12-15) compared to its congeners. H. ampalong, H. bimaculata and H. salweenensis can be trickier to separate since they all have two body blotches. H. ampalong possesses more lateral line scales than H. salweenensis (28-31 vs. 26-27) whereas in H. bimaculata the body markings are saddle-shaped and the anterior blotch is positioned underneath the posterior half of the dorsal-fin (below the dorsal-fin origin in the other two).

It is worth noting that the body markings tend to fade in very large specimens of all Hampala spp., and it's possible that additional species will be described in the future as a phylogenetic study published in 2006 concluded that the form of H. bimaculata from central and southern parts of the Malaysian state of Sarawak, Borneo ought to be considered distinct, for example.