Edit Akysis vespertinus

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Name

Scientific name

Akysis vespertinus

Described by

Authority Ng, Year 2008

Family

Akysidae

Common names

Western Stream Catfish

Photograph credits

All 1 credited

Summary

The western stream catfish, Akysis vespertinus, is an akysid catfish known only from the Ann Chaung river system in Rakhine State, western …

Size and aquarium

Maximum size

35mm, standard length

Aquarium size

Minimum length 45 cm, Minimum depth 30 cm, Water movement High: fast-flowing river or riffle

Water

Water conditions

Temperature 16.5–24°C, pH 6–7.5

Hardness

2–12dGH

Conductivity

Not recorded

Behaviour

Temperament

Peaceful

Community suitability

Community-safe

Where it lives

Countries, regions, rivers and lakes

Myanmar, Ann Chaung

Writing

Etymology

Akysis: from the Greek á- (Gr. ἀ), meaning 'not, without' and kýstis (Gr. κύστις), meaning 'bladder', in reference to genus members lacking a swim bladder. ves…

Distribution

Known only from headwaters of the Ann Chaung river system which drains the western face of the Rakhine Yoma/Arakan mountains in Rakhine state, western Myanmar.…

Habitat

Members of this genus are near-exclusive inhabitants of swiftly-flowing streams and rivers with substrates generally consisting of any combination of sand, gra…

Aquarium size

A tank with base dimensions of 45 ∗ 30 cm is more than sufficient, even for a group.

Maintenance

Not difficult to keep but should really be provided with a soft, sandy substrate since some of its time is spent completely buried, or with only eyes protrudin…

Water conditions

Not written yet

Diet

Akysis species are primarily nocturnal micropredators feeding on small aquatic crustaceans, worms, insect larvae and other zooplankton. They can be a little pi…

Behaviour and compatibility

Not especially competitive and should not be kept with much larger or more aggressive fishes. Miniature schooling cyprinids such as Boraras, Microdevario or sm…

Sexual dimorphism

Unreported, but sexual dimorphism has been reported in A. alfredi (Ng and Kottelat, 1998)[8], A. fuscus (Ng, 1996)[2] and A. microps (Ng and Tan, 1999)[3]. In …

Reproduction

Unreported, though a short report was published in the description of A. vespa (Ng and Kottelat, 2004)[9], in which a successful spawning event in that species…

Notes

This species is exceptionally rare in the aquarium trade and can be distinguished from congeners by the following combination of characters: snout narrow with …

This species is exceptionally rare in the aquarium trade and can be distinguished from congeners by the following combination of characters: snout narrow with head appearing triangular as a result; pectoral spine measuring 17.1-22.2 % of standard length (SL); base of adipose fin measuring 18.8-21.1 % SL; body depth at anus 135-16.0 % SL; caudal peduncle depth 7.4-9.2 % SL; caudal peduncle length 19.0-22.8 % SL; head length 27.1-30.2 % SL; interorbital distance 24.5-28.8 % ofn head length (HL); nasal barbel measuring 37.8-48.3 % HL; maxillary barbel measuring 84.9-96.6 % HL; no serrations on posterior margin of pectoral fin spine; caudal fin forked; possession of two lightly-coloured, saddle-shaped markings on upper surface of the postdorsal region (area between dorsal and caudal fins); abdomen without brown pigmentation.

Members of the family Akysidae are often referred to collectively as 'Asian stream catfishes' since the majority are exclusive inhabitants of such environments. All have four pairs of barbels, and within this larger grouping Akysis species are diagnosable by possession of tuberculate skin and cryptic colour patterning typically comprising yellowish bands or blotches on a brownish background.

Based on various morphological aspects Ng and Kottelat (1998)[8] split the genus as originally accepted into the A. variegatus and A. pseudobagarius species groups, but all those of the latter group were reassigned to the genus Pseudobagarius by Ferraris (2007) on the basis of the following shared characters: tip of snout extends anterior to margin of lower jaw; mouth subterminal; narial openings (anterior and posterior nostrils) relatively large and closely-set; caudal fin deeply forked.

Pseudobagarius spp. also tend to have a relatively extended body shape compared with Akysis, while in the latter the snout tip extends only slightly beyond the margin of the lower jaw, mouth orientation terminal to slightly subterminal, narial openings relatively small and widely-spaced and caudal fin truncate or emarginate.

In recent phylogenetic analyses the family Akysidae has been grouped into an assemblage informally referred to as 'Big Asia' where it occupies a basal position and is most closely related to the families Amblycipitidae, Sisoridae and Erethistidae, these apparently forming a monophyletic group alongside the Bagridae and Horabagridae.

The South American family Aspredinidae has often been affiliated with Akysidae in earlier studies, but is now considered more closely associated with the Doradidae and Auchenipteridae.

All akysids possess venom apparatus at the base of the dorsal and pectoral spines and though not dangerous to a healthy human can inflict a painful sting, so should be handled with care when being removed from the water for any reason or during aquarium maintenance.

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References

13 on this profile

Name

Scientific name

Described by

Family

Common names

Photograph credits

Summary

Size and aquarium

Maximum size

Aquarium size

Water

Water conditions

Hardness

Conductivity

Behaviour

Temperament

Social needs

Community suitability

Where it lives

Countries, regions, rivers and lakes

Writing

Etymology

Distribution

Habitat

Aquarium size

Maintenance

Water conditions

Diet

Behaviour and compatibility

Sexual dimorphism

Reproduction

Notes

References

References