Phalacronotus apogon (BLEEKER, 1851)

SynonymsTop ↑

Silurus apogon Bleeker, 1851; Kryptopterus apogon (Bleeker, 1851); Micronema apogon (Bleeker, 1851); Silurus leptonema Bleeker, 1852; Silurus micropogon Bleeker, 1855

Etymology

apogon: from the Greek prefix a-, meaning ‘without’, and pogon, meaning ‘beard’, in reference to this species’ short barbels.

Classification

Order: Siluriformes Family: Siluridae

Distribution

This species is currently understood to occur throughout much of Southeast Asia including major river systems in Thailand, Laos, Cambodia, Vietnam and Peninsular Malaysia plus the Greater Sunda Islands of Sumatra, Borneo and Java.

Type locality is ‘Bandjarmasin, southern Kalimantan, Borneo, Indonesia’ which corresponds to a town located on the Barito River and now more commonly referred to as ‘Banjarmasin’ in South Kalimantan (Kalimantan Selatan) province, Indonesia (Borneo).

It’s possible that the mainland and Sundaic populations may represent separate species but this remains to be confirmed, and the species also exists in both mottled and laterally-striped colour forms.

Habitat

Pelagic and inhabits main river channels and large streams which are often murky due to suspended sediment, and moves into temporarily-flooded zones during the wet season.

Maximum Standard Length

600 – 700 mm.

Aquarium SizeTop ↑

Suitable only for public installations or the very largest private aquaria.

Maintenance

Décor is relatively unimportant although this species prefers weakly-lit conditions.

Do not add introduce it to a biologically immature aquarium as it can be susceptible to swings in water chemistry.

Water Conditions

Temperature: 20 – 27 °C

pH: 6.0 – 7.5

Hardness: 36 – 268 ppm

Diet

An obligate but generalised piscivore which hunts pelagic fishes in the middle-and-upper water column in nature.

Newly-imported specimens often refuse to accept anything but live fishes but most can be weaned onto dead alternatives once recognised as edible.

Like the vast majority of predatory fishes this species should not be fed mammalian or avian meat like beef heart or chicken, and similarly there is no benefit in the long-term use of ‘feeder’ fish such as livebearers or small goldfish which carry with them the risk of parasite or disease introduction and at any rate tend not have a high nutritional value unless properly conditioned beforehand.

Behaviour and CompatibilityTop ↑

Best kept alone or with similarly-sized, non-aggressive fishes since it’s actually quite peaceful with species too large to be considered food and can apparently be maintained in a group in a suitably-sized aquarium.

Sexual Dimorphism

Adult males are noticeably slimmer than females and the posterior edge of the pectoral-fin spine is serrated (vs. smooth in females).

Reproduction

Unrecorded in aquaria but in nature spawning coincides with the onset of the wet season and associated seasonal floods.

NotesTop ↑

Arguably should not be considered a home aquarium subject at all given its eventual size and natural behaviour, and we know of only a handful of private aquarists with the facilities required to house it long-term.

Unfortunately, juveniles are sometimes seen for sale under names such as ‘blue neon sheatfish’ or ‘metallic cheatfish’, and most often without adequate information regarding long-term care.

P. apogon has formerly been placed within the genera Kryptopterus, Micronema (Rainboth, 1996) and more recently Phalacronotus (Ferraris, 2007) and is an important food fish across much of its native range.

It’s very similar to P. micronema but can be told apart by its longer head (HL fits 4.6± 5.3 times in SL vs 5.3± 5.7).

The genus currently contains four species which are separated from other silurids by a combination of the following characters: absence of dorsal-fin; 9-10 pelvic-fin rays; maxillary barbels  short (not extending beyond the opercle).

References

1. Ferraris, C. J., Jr., 2007 - Zootaxa 1418: 1-628
   Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types.
2. Kottelat, M. and E. Widjanarti, 2005 - The Raffles Bulletin of Zoology Supplement 13: 139-173
   The fishes of Danau Sentarum National Park and the Kapuas Lakes area, Kalimantan Barat, Indonesia.
3. Ng, H. H., S. Wirjoatmodjo and R. K. Hadiaty, 2004 - Ichthyological Exploration of Freshwaters 15(1): 91-95
   Kryptopterus piperatus, a new species of silurid catfish (Teleostei: Siluridae) from northern Sumatra.
4. Parenti, L. R. and K. K. P. Lim, 2005 - The Raffles Bulletin of Zoology Supplement 13: 175-208
   Fishes of the Rajang Basin, Sarawak, Malaysia.
5. Roberts, T. R., 1989 - Memoirs of the California Academy of Sciences No. 14: i-xii + 1-210
   The freshwater fishes of western Borneo (Kalimantan Barat, Indonesia).
6. Tan, H. H. and H. H. Ng, 2000 - Journal of Natural History 34(2): 267-303
   The catfishes (Teleostei: Siluriformes) of central Sumatra.
7. van Oijen, M. J. P., G. M. P. Loots and F. J. G. Limburg , 2009 - Zoologische Mededelingen (Leiden) No. 83: iii-xi + 1-317
   English translation of: P. Bleeker, A Precursor of the Fishes of the Indian Archipelago. Part 1 -- Siluri.