Ompok bimaculatus

Butter Catfish

Classification

Siluridae

Distribution

A widespread species having been recorded in Afghanistan, India, Pakistan, Nepal, Bangladesh, Sri Lanka, China, Myanmar, Thailand, Cambodia, Laos, Vietnam and Indonesia.

Habitat

In what would seem a direct correlation with its ample distribution, this fish is found in a variety of biotopes, from slow-moving, turbid streams, to canals and flowing rivers. The fish tend to migrate to flooded areas during the wet season.

Maximum Standard Length

18″ (45cm), though usually smaller in aquaria.

Aquarium SizeTop ↑

72″ X 24″ X 24″ (180cm x 60cm x 60cm) – 680 litres.

Maintenance

This species requires a lot of open swimming space, along with some suitably-sized hiding places. Lengths of thick plastic piping should be adequate for this, as it is doubtful that any aquatic plants could withstand the movements of a fish this size. Filtration should be powerful and efficient, as this fish is a messy eater and produces a lot of waste. It is also sensitive to deteriorating water conditions and regular water changes must be strictly observed. Some degree of current is also preferred.

Water Conditions

Temperature: 68-79°F (20-26°C)

pH: 6.0-8.0

Hardness: 4-28°H

Diet

Relatively unfussy and will take most live, frozen and dried foods. Offer larger specimens earthworms, pieces of prawn and mussel and dried pellets.

Behaviour and CompatibilityTop ↑

Fairly peaceful and shy for its size, although it will eat any smaller fish it can fit in its mouth. It has a mouth full of razor sharp teeth to reinforce this point. Good tankmates include medium to large sized cyprinids, characins, similarly-sized Asian or South American catfish and larger cichlids.

Sexual Dimorphism

Males have a serrated edge to the pectoral spine, which females lack. Mature females are thicker-bodied than males.

Reproduction

Thus far only achieved through the use of hormone injections in captivity.

NotesTop ↑

This infrequently seen (in the trade) species is also known as the two spot glass catfish, for fairly obvious reasons. It is more than likely that a number of separate species are currently considered within this one, as there are clear morphological differences between populations. Pending a taxonomic revision, these currently all remain classified as O.bimaculatus. This would also seem to explain the apparent toleration of the fish to wildly different water chemistry. Xanthic and albino forms are also occasionally available in the hobby, although these seem to be confined to the Southeast Asian ‘species‘. Taxonomy aside, it’s considered a fine food fish in many of its native countries in both fresh and smoked forms.