A pair of 15 cm Hard-lipped Barb in a shallow forest stream, Singapore.  Note the black marking at the base of the tail fin, and the pale margin of the pelvic and anal fins.
 

Family : CYPRINIDAE
Species : Osteochilus hasselti
Maximum Length : 30 cm

References : F1

The Hard-lipped Barb is a laterally-compressed, rhomboidal-shaped fish. It is mainly silvery in colour, but its   dorsal surface is sometimes greenish. The fins are deep red, and the margins of the pelvic and anal fins are pale. The tail fin is deeply forked, and the barbels small. At the base of the tail fin is a single black marking.

The species is mainly herbivorous, feeding on algae and phytoplankton.

This is a common species occurring in a number of Southeast Asian countries including Peninsular Malaysia and parts of Indonesia. Recently found in Singapore, it is suspected of having been introduced. In the Mekong River Basin of Thailand, Laos and Cambodia it is abundant and there a maximum length of 30cm has been recorded.