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Ompok bimaculatus (Bloch, 1794)           

On to the month of August 2005 we welcome back author Chris Ralph who is the catfish expert to the U.K. fishkeeping magazine 'Tropical Fish'. Chris concentrates on his favourite cats 'The biggies' with a look at the Asian catfish, Ompok bimaculatus.


his particular species can be found widespread throughout Asia in the rivers of Afghanistan to China, Thailand and Borneo. This particular catfish has endangered status in the Western Ghats in India and is documented as being found in both freshwater and brackish environments. Ompok bimaculatus naturally occurs in streams and rivers which range in size and flow with currents that can best be described as sluggish to moderate. The rivers are usually quite shallow ranging from 0.5 to 1.5m in depth, and are often muddy and murky. These large catfish are also found in canals and inundated fields into which they move during the flood season. These catfish can attain a length of 450mm or 18” standard length.

Ompok bimaculatus

 

The ideal water parameters for these catfish are pH in the range of 6-8, hardness in the range of 4-28°dGH and temperature in the range of 20-26°C. This is one of the larger species of catfish, and due to the size that it can attain I would not recommend that you keep this catfish in with small fish as they are most likely going to form part of its diet. Also this particular species requires a larger size aquarium and I would suggest a minimum of 72” x 24” x 24” for it. You are most unlikely to see this catfish amongst importations due to the fact that it is a food fish in the countries in which it naturally occurs. Where offered for sale as a food fish you might encounter Ompok bimaculatus being sold fresh or smoked on skewers!


 

 

Update: Ompok siluriodes was at one time a synomyn for O. bimaculatus but O. siluriodes has a marbled body pattern against the silver of O. bimaculatus.



Characteristics
The body is elongated? The dorsal fin is described as being small and has a total of 4 soft rays, whilst the anal fin which is described as being long has a total of 54-74 soft rays. The pelvic fins are described as being small with 7-8 soft rays. The pectoral fins have 12-14 soft rays. The caudal fin is forked. Ompok bimaculatus has two pairs of barbels; one pair of maxillary barbels which reach the reaching anal fin; and one pair of mandibular barbels which are described as being small in length. The eyes are small and are covered by skin. Ompok bimaculatus is described as having vomerine teeth in 2 patches.

Colour
The base colour of the body is silver, with a conspicuous round black blotch above and behind the pectoral fin base. The second of the two spots is at the base of the caudal peduncle hence the species name bimaculatus.

Compatibility
Ompok bimaculatus is described as being peaceful but, has quite a large mouth, and it is for this reason that I would suggest that you keep this catfish as part of a shoal of its own kind or with other large species of fish.

Sexual differences
The males tend to be more slender than the females and are described as having serrations on the posterior edge of the pectoral fin spines, whilst the female’s pectoral fins lack these serrations.

Breeding
There are no known documented spawnings of this catfish in aquaria, which is most likely due to the fact that this catfish is rarely imported and also due to the size of aquarium required. Whilst there are no documented aquarium spawnings it is documented that these catfish are bred in India using hormone injections.

Feeding
The natural diet of this catfish includes vegetable matter, fish, crustaceans and molluscs. In captivity these catfish readily accept catfish pellets, prawns and frozen foods.

Etymology
Ompok: It has been suggested that the name is a bad reproduction of the Malay name 'limpok'. Or from the vernucular name, 'Ompok'
bimaculatus : With two spots


Glossary of Terms
Mandibular - in relation to the mandible or lower jaw.
Maxillary
- in relation to the maxilla, the bone of the upper jaw.
Vomerine - teeth present on the vomer.
Vomer - the anterior bone in the mid-line of the roof of the mouth.


References
Froese, R. and D. Pauly. Editors. 2005. FishBase.World Wide Web electronic publication. www.fishbase.org, version (07/2005).
www.planetcatfish.com


Photo Credits
© Beta Mahatvaraj @ Indianaquariumhobbyist.com
Factsheet 110
Synonyms:
Silurus bimaculatus, Callichrous bimaculatus, Pseudosilurus bimaculatus, Phalacronotus siluroides, Ompok siluroides, Ompok canio, Silurus canio, Schilbe pabo, Silurus chechra, Silurus duda, Callichrus affinis, Callichrus immaculatus, Callichrus nebulosus, Wallago microcephalus, Silurus mysoricus, Silurus indicus, Callichrous gangeticus, Callichrous macrophthalmus, Callichrous sindensis, Wallago miostoma, Ompok sindensis.
Common Name:
Two-spot Glass Catfish, Glass Catfish, Butter Catfish 
Family:
Siluridae or Sheathfishes
Subfamily:
Silurinae
Distribution:
Indian subcontinent and Myanmar.
Aquarium size:
72” x 24” x 24” (180 x 60 x 60mm)
Size: 
450mm s.l. (standard length is the measurement from the tip of the snout to the base of the caudal peduncle).
Temp:
20-26°C (67-79°F)
pH.:
6.0 - 8.0
Hardness:
4-28°dGH
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                                                                                                                                               Factsheet 110 = updated January 16, 2015 , © ScotCat 1997-2015 Go to Top