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ollowing on from our last Ompok factsheet which was 18 years ago in 2005 and featured the "Butter Catfish" Ompok bimaculatus, we again visit the Siluridae family for our September 2023 factsheet featuring Ompok siluroides from the Mekong and Chao Phraya River drainage's in Indochina, the Malay Peninsula, and the Barito River drainage in southern Borneo and Java.

 Ompok siluroides

The genus is recognised to be paraphyletic. The species of Ompok have been grouped into species groups, such as the Ompok bimaculatus group (O. bimaculatus, O. malabaricus, O. miostomus, O. siluroides), the O. eugeneiatus group (O. eugeneiatus, O. pinnatus), the O. hypophthalmus group (O. hypopthalmus, O. rhabdinurus, O. urbaini), and the  O. leiacanthus group (O. fumidus, O. jaynei, O. leiacanthus). On the other hand, the monophyly of these species groups is not strong enough to reassign species to other genera. The O. eugeneiatus group is likely to be more closely related to Kryptopterus than the other Ompok species.

This species was at one time a synonym for O. bimaculatus but this species has a silver body. There are two distinct forms of O. siluroides where the background pattern differs with the species from the Mekong with a pale brown colouration on one and the other form which has a mottled body pattern. With these two colour forms they are found syntopically.

  Ompok siluroides - xanthic specimen

Occurs in streams and rivers of all sizes with currents ranging from sluggish to moderate. It is known from river drainage's in mainland Southeast Asia (Mekong River drainage southwards to Singapore and eastwards to the Song Ba drainage in central Vietnam), Sumatra (Deli River drainage southwards to the Way Seputih drainage), Java (Ciujung drainage eastwards to the Kali Brantas drainage) and Borneo (Baram River drainage southwards to the Barito River drainage). Its Extent of Occurrence (EOO) is estimated at 3,533,730 km2 based on a minimum convex polygon calculated using data in Ng and Hadiaty (2009) and GBIF (2019), (IUCN 2019).

None

Phalacronotus siluroides, Wallago krattensis, Ompok krattensis.

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Asia: Mekong and Chao Phraya River drainages in Indochina, the Malay Peninsula, the Barito River drainage in southern Borneo and Java.

21.5cm. (8½ins)

20-26°C (67-79°F)

Dorsal soft rays (total): 4; Anal soft rays: 54 - 74. Two pairs of barbels; maxillary barbels reaching pelvic fins or anal fins; mandibulary barbels minute, about as long as diameter of eye. Eyes small, covered by skin. Dorsal and pelvic fins small; anal fin long; pectoral fins well developed vomerine teeth in 2 patches.

This is one of the smaller species in this genera so should be okay for a large aquarium with fish of the same size or larger. Will still be a predator of smaller fish in the aquarium. As of most catfish they will prefer hiding places such as pipes or driftwood.

Not recorded.

Males are slimmer and have serrations on the posterior edge of the pectoral spine, females lack these serrations.

Moves into freshly inundated habitats during the flood season and feeds on crustaceans and mollusks. In the aquarium they will take most aquarium fare such as tablet, pellet, live and frozen foods.

Anal fin: The median, unpaired, ventrally located fin that lies behind the anus, usually on the posterior half of the fish.
Caudal fin: The tail.
Dorsal fin: The primary rayed fin(s) on top of the body.
Mandibular barbels: Pertaining to the lower jaw. (mandibular barbels).
Maxillary barbels : Pertaining to the upper jaw. (maxillary barbels).
Monophyly: The term monophyly, or monophyletic, derives from the two Ancient Greek words µóvoç (mónos), meaning "alone, only, unique", (phûlon), meaning "genus, species", and refers to the fact that a monophyletic group includes organisms (e.g., genera, species) consisting of all the descendants of a unique common ancestor.
Paraphyletic: Of a group of organisms, descended from a common evolutionary ancestor or ancestral group, but not including all the descendant groups.
Pectoral fins: The paired fins just behind the head.
Pelvic fin: The paired fins, between the pectorals and the anal fins. (also referred to as ventrals).
Syntopically: Referring to a type of analysis in which different works are compared and contrasted.
Vomerine teeth: Thin and sharp, more or less protruding according to the species, the vomerine crest (Crista vomeris) is the caudal, or guttural part of the ventral part of the vomer bone.
Xanthic: Relating to, or tending towards a yellow colour.

Ompok: It has been suggested that the name is a bad reproduction of the Malay name 'limpok'. Or from the vernucular name, 'Ompok'.
siluroides: –oides, having the form of: Silurus, a related genus from Europe, but in this case perhaps referring to catfishes in general.

Photo Credits

© Johnny Jensen @  
Map: © By Kmusser - File: Chaophrayarivermap.png using Digital Chart of the World and GTOPO data., CC BY-SA 3.0.