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his month (March 2022) we report on what is basically a marine or brackish water species found along the coasts from the Ariidae family, the Soldier catfish, Osteogeneiosus militaris and a fish although it reaches a manageable standard length of 35.0cm (14ins), is probably not suitable for the home aquarium due to its meanderings from marine and brackish conditions and sometimes entering fresh waters in exceptional circumstances.

Osteogeneiosus militaris - Vietnam

There are specimens from this monotypic (only one genus and species) that sport yellow in the fins. These individuals are usually found in the Northern Gulf of Thailand and still have the black or dark blue to the adipose and caudal fin tips. Osteogeneiosus militaris is found in the Indian and western Pacific Oceans from Pakistan to the Malay Archipelago.

Osteogeneiosus militaris - Pakistan, Karachi Fish Harbour

What is unusual about Osteogeneiosus militaris is that it differs from all other ariid species in having only one pair of semi-osseous maxilary barbels and no mental barbels. These maxillary barbels are stiff (semi-osseous) and not flexable like most members of the Ariidae family. The type species is Arius militaris Valenciennes, 1840 (= Silurus militaris Linnaeus, 1758). Type by subsequent designation by Bleeker (1862: 8; 1863: 93). Gender: Masculine.

Remarks: At present, there is only one recognised valid species in Osteogeneiosus.

Soldier catfish

Silurus militaris

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Indo-West Pacific: Distributed along the Indo-Pacific region from the west coast of India to Bangladesh, Myanmar, Singapore, Malacca, Indonesia, Brunii, Darussalam, Malaysia and Pakistan. Type Locality: Asia. No types known.

35.0cm (14ins)

n/a

n/a

Dorsal profile of head rising as a gentle slope to first dorsal fin base; only one pair of stiff, semiosseous maxillary barbels, mental barbells absent; head shield smooth without granulations or rugose striations; supraoccipatal process narrow, more than twice longer than broad, its hind end narrowly curved; median longitudinal groove broad, not reaching to base of supraoccipital process; predorsal plate crescent shaped; premaxillarv band of teeth in upper jaw 5 times as long as broad, mandibulary band of teeth narrow, medially interrupted; palate teeth conical, in 2 widely separated but posteriorly converging semioval patches on each side. First dorsal and pectoral fins each with a strong spine; total anal fin rays 19 to 22. All other species of Ariidae: have 1 or 2 pairs of mental barbels (absent in O. militaris); maxillary barbels slender (not stiff or semiosseous). Differs from all other ariid species in having only a pair of semi-osseous maxilary barbels.

Top of head and back intense dark blue. belly with lighter shades sparingly dotted with black spots; greyish white, minutely spotted with black, tips of first dorsal and adipose fins dark blue.

Not suitable for the aquarium hobby.

This species is a mouth brooder and incubates the eggs in their mouths, and for a time the young fish too, fasting in all for a period of 6 weeks. Gestating males were found starving. The occurrence of mature females and gestating male parents indicate that they spawn during August-April. The maximum number of incubated eggs recorded from oro – buccal cavity of O. militaris was 56 eggs.

Not reported, but in this family the females pelvic fins are modified in shape by having on the inner side a thick flap which is believed to be used to hold the eggs temporarily before they are transferred to the males mouth.

Feeds mainly on invertebrates and small fishes.

Adipose fin: Fleshy finlike projection without rays, behind the rayed dorsal fin.
Caudal fin: The tail.
Dorsal: The primary rayed fin(s) on top of the body.
Maxillary Barbels: Pertaining to the upper jaw. (maxillary barbels).
Mental Barbels: Pertaining to the chin, on the lower jaw. (mental barbels).
Pectoral fins: The paired fins just behind the head.
Pelvic fins: The paired fins, between the pectorals and the anal fins (also referred to as ventrals).
Premaxillary: In relation to the premaxilla (an upper jaw bone) e.g. premaxillary tooth band.
Supraoccipatal: Unpaired bone at the back of the skull, usually with a crest.

Osteogeneiosus: Greek, osteon = bone + Greek, gene, genes = birth, race.

FAO Species Identification Sheets. Family: Ariidae 1983.
Ferraris, C.J. Jr., 2007. Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types. Zootaxa 1418:1-628.
Froese, R. and D. Pauly. Editors. 2022. FishBase. World Wide Web electronic publication. www.fishbase.org, version (02/2022).
Hossain, Mohammad & Sivasubbu, Sridhar & Scaria, Vinod & JK, Jena & Ponniah, A.G. & Orbán, László. (2014). Barcoding of Asian seabass across its geographic range provides evidence for its bifurcation into two distinct species. Frontiers in Marine Science.
Jayaram, K.C., 1984. Ariidae. In W. Fischer and G. Bianchi (eds.) FAO species identification sheets for fishery purposes. Western Indian Ocean fishing area 51. Vol. 1. FAO, Rome. pag. var.
Jayaram. K.C. 2006, Catfishes of India. Narendera Publishing House. 383p.
Vij, Shubha & Kathiresan, Purushothaman & Gopikrishna, Gopalapillay & Lau, Doreen & Saju, Jolly & Vellarikkal, Shamsudheen & Katneni, Vinaya Kumar & Basheer, V S & Gopalakrishnan, Dr &
Wheeler, Alwyne. Fishes of the World. An illustrated Dictionary. Ferndale Editions London. 1975. 366 P.
Wikipedia.org
WoRMS Editorial Board (2022). World Register of Marine Species.

Photo Credits

First image: © Fishes of Mainland Southeast Asia
Second image: © H. B. Osmany
Map: Vij, Shubha & Kathiresan et al.