Edit Sewellia sp. 'SEW02'

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Name

Scientific name

Sewellia sp. 'SEW02'

Described by

Not recorded

Family

Gastromyzontidae

Common names

Not recorded

Photograph credits

All 5 credited

Summary

Sewellia sp. 'SEW02' is an undescribed hillstream loach whose trade specimens are thought to originate in Hue province, central Vietnam. It…

Size and aquarium

Maximum size

65mm, standard length

Aquarium size

Minimum length 75 cm, Minimum depth 30 cm, Water movement Very high: hillstream or torrent

Water

Water conditions

Temperature 18–24°C, pH 6–7.5

Hardness

1–10dGH

Conductivity

Not recorded

Behaviour

Temperament

Not recorded

Community suitability

Community-safe

Where it lives

Countries, regions, rivers and lakes

Vietnam

Writing

Etymology

Not written yet

Distribution

Unconfirmed but the fish collected for the aquarium trade are thought to originate in Hue province, central Vietnam.

Habitat

Sewellia spp. are mostly restricted to shallow, fast-flowing, highly-oxygenated headwaters and tributaries characterised by stretches of riffles and runs broke…

Aquarium size

Minimum base dimensions of 75 ∗ 30 cm are recommended for general care. Smaller tanks can be used for breeding.

Maintenance

The water must be clean, well-oxygenated, and ideally turn over 15-20 times per hour so we suggest the use of an over-sized filter as a minimum requirement plu…

Water conditions

Temperature: Can tolerate higher temperatures provided its oxygen requirements are maintained but for general aquarium care a value of 18 – 24 °C is recommende…

Diet

Much of the natural diet is composed of benthic algae plus associated micro-organisms although insect larvae are probably taken on an opportunistic basis. Home…

Behaviour and compatibility

In terms of behaviour Sewellia spp. are perhaps the most dominant of the 'sucker belly' group of loaches though they're not generally aggressive towards dissim…

Sexual dimorphism

The most obvious external characteristics are the shape of the head and body when viewed from above, with females having a comparatively broad body and a snout…

Reproduction

Sewellia spp. are arguably the easiest of all loach species to breed in aquaria and success has been achieved with several species. Initial reports mostly desc…

Notes

This species first became available in early 2009 and was initially identified as S. breviventralis (Freyhof and Serov, 2000)[3] because there is a clear space…

This species first became available in early 2009 and was initially identified as S. breviventralis (Freyhof and Serov, 2000)[3] because there is a clear space between the pelvic and anal fins plus body patterning is vaguely similar to that species, and it's also quite similar to S. elongata (Roberts, 1998)[8] and S. sp. 'SEW03'

It does not fully match the descriptions of either species, however, and therefore remains in need of identification.

It's sometimes referred to as 'butterfly loach', a generic vernacular name used for several balitorids, most notably Beaufortia kweichowensis.

Prior to the mid-1990s S. lineolata was the only species in the genus but an upturn in surveys of freshwater fauna in Vietnam and Laos has resulted in the discovery of various new taxa, several of which remain undescribed.

The first addition was S. marmorata (Serov, 1996)[10] and this was followed by the description of a further four species in Roberts' 1998 revision.

He considered the larger-growing representatives with relatively short pelvic fins (S. elongata and S. diardi) to belong to his new subgenus Diardichthys.

Freyhof and Serov (2000) found S. marmorata and S. patella to exhibit a combination of characters applicable to both subgenera, however, thus Diardichthys is currently considered a synonym of Sewellia.

The genus is diagnosed by the following combination of characters as per Freyhof and Serov (2000): depressed head and body and compressed tail; greatest body depth at dorsal-fin origin; greatest body width at end of pectoral-fin base; entire ventral surface of paired fins, head and body forming an adhesive disc extending to end of pelvic fin; one simple and 19-26 branched pectoral-fin rays, one simple and 18-21 branched pelvic-fin rays; pectoral fin extending beyond pelvic-fin origin; last two pelvic-fin rays not exposed ventrally, but reflexed dorsally and adpressed to side of body, forming a pelvic valve together with a thick fleshy flap on posterior part of pelvic-fin base (where pelvic fin attaches to side of body); gill opening smaller than eye diameter, covered by a vertically oblique, biconvex membranous flap; gill opening entirely above pectoral-fin base; mouth very small, strongly curved; rostral cap continuous with upper lip; upper jaw overhanging lower jaw; two pairs of short rostral barbels and one pair of maxillary barbels; rostral barbels with medially expanded papilliferous bases, partly adjacent or overlying to cavities of ventral surface of head; these cavities not connected to each other; bases of two anterior barbels fused; rostral barbels connected laterally with a small skin-fold to head; maxillary barbel short and filamentous, with a few small papillae.

Sewellia spp. have specialised morphology adapted to life in fast-flowing water; the paired fins are orientated horizontally, head and body flattened and the last two pelvic-fin rays combine with a fleshy flap on the base of the fin to form a 'pelvic valve'.

These features form a powerful sucking cup which allows the fish to cling tightly to solid surfaces.

The ability to swim in open water is greatly reduced and they instead 'crawl' their way over and under rocks.

The family Gastromyzontidae is currently considered valid as per Kottelat (2012).

It contains a number of genera which had formerly been included in several families and subfamilies, most recently Balitoridae, of which the most well-known in the aquarium hobby include Beaufortia, Formosania, Gastromyzon, Pseudogastromyzon, Hypergastromyzon, Liniparhomaloptera, Sewellia, and Vanmanenia.

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References

11 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