Desmopuntius gemellus (KOTTELAT, 1996)

SynonymsTop ↑

Puntius gemellus Kottelat, 1996

Etymology

Desmopuntius: from the Ancient Greek δεσμψτης (desmotes), meaning ‘prisoner’, and the generic name Puntius, in reference to the barred colour pattern in member species.

gemellus: from the Latin gemellus, meaning ‘twin’, in allusion to this species’ similarity to ‘P.‘ johorensis.

Classification

Order: Cypriniformes Family: Cyprinidae

Distribution

The type series was purchased from a market in Jambi province, eastern Sumatra, Indonesia and this species is also known from neighbouring Riau province plus the island province of Bangka.

On Sumatra it may be restricted to the Indragiri and Batang Hari river systems.

Habitat

Inhabits peat swamp forests and associated black water streams in which the water is typically stained brown with humic acids and other chemicals released by decaying organic material.

The dissolved mineral content is generally negligible and the pH can be as low as 3.0 or 4.0, and the substrate is usually littered with fallen leaves, branches and submerged tree roots.

Maximum Standard Length

80 – 100 mm.

Aquarium SizeTop ↑

Base dimensions of at least 120 ∗ 45 cm or equivalent are required.

Maintenance

Will thrive in a heavily-planted or forest stream-type set-up, the latter comprising a soft substrate, dim lighting, roots, branches and leaf litter.

You could also add aquatic plants that can survive under such conditions such as Microsorum, Taxiphyllum, or Cryptocoryne spp.

Water Conditions

Temperature: 22 – 25 °C

pH: 4.0 – 7.0

Hardness: 18 – 179 ppm

Diet

Wild fish are probably foragers feeding on diatoms, algae, organic detritus, small insects, worms, crustaceans, and other zooplankton.

In the aquarium it’s easily-fed but the best condition and colours offer regular meals of small live and frozen foods such as bloodworm, Daphnia, and Artemia, alongside good quality dried flakes and granules, at least some of which should include additional plant or algal content.

Behaviour and CompatibilityTop ↑

An ideal addition to a peaceful community of Southeast Asian fishes with comparably-sized, open water-dwelling cyprinids and small loaches perhaps constituting the best choices.

Some of the more commonly exported species native to Sumatra include Striuntius lineatus, Brevibora dorsiocellata, Rasbora einthovenii, Trigonopoma pauciperforatum, T. gracile, Trigonostigma hengelii, and various Pangio spp.

It’s a schooling species by nature, and really should be kept in a group of at least 8-10 specimens.

Maintaining it in decent numbers will not only make the fish less skittish but result in a more effective, natural-looking display, and males will also display their best colours as they compete with one other for female attention.

Sexual Dimorphism

Adult males are likely to be slightly smaller, are noticeably slimmer and exhibit more intense colouration than females.

Reproduction

Unrecorded.

NotesTop ↑

This rarely-traded species is one of three similar-looking members of the genus alongside D. johorensis and D. trifasciatus, while it may also be confused with Striuntius lineatus.

Juveniles of all except S. lineatus exhibit a vertically-barred rather than laterally-striped colour pattern, the metamorphosis to adult patterning beginning at around 20 mm SL and normally being complete by 30-40 mm.

D. gemellus can be told apart from the other three species by the following combination of characters: interaxial streak present on scale row +1 below dorsal-fin base; specimens larger than 20 mm SL with 5-6 dark lateral stripes on body; stripes thin, typically less than half a scale row deep; 2 pairs of barbels, posterior pair usually reaching beyond posterior margin of eye; 1/24/1/3 in transverse row between dorsal-fin origin and anal-fin origin; 7-11 gill rakers on anterior gill arch; mouth terminal; lower lip thin and post-labial groove interrupted medially; specimens smaller than 18 mm with 4-5 irregular dark fkank markings.

It was formerly included in the genus Puntius which was for a number of years viewed as a polyphyletic catch-all containing over 100 species of small to mid-sized cyprinid until Pethiyagoda et al. (2012) published a partial review covering South Asian members.

The majority of sub-Himalayan Puntius species were reclassified and new genera Dawkinsia, Dravidia (subsequently amended to Haludaria), and Pethia erected to accommodate some of them, with the remainder either retained in Puntius or moved to the existing Systomus assemblage, though the definition of the latter was altered meaning some Southeast Asian species formerly placed there could no longer be considered members.

Kottelat (2013) published a comprehensive nomenclatural update for Southeast Asian fishes in which the genus Desmopuntius was raised and diagnosed as follows: unique colour pattern made of 4–6 bars at least in juveniles, anterior bar across eye, 2nd bar behind gill opening, 3rd bar at dorsal-fin origin, 4th bar at anal-fin origin, 5th bar at middle of caudal peduncle, and 6th at caudal-fin base; often a black spot at posterior extremity of dorsal-fin base. In D. gemellus, D. johorensis and D. trifasciatus the barred  pattern is present only in juveniles and with increasing size transforms into a striped pattern.

In addition, the following characters are useful in identification of Desmopuntius spp.: last simple dorsal-fin ray serrated posteriorly; rostral and maxillary barbels present; lips smooth and thin, postlabial groove interrupted medially; lateral line complete, with 25–27 pored scales on body; ½4/1/4½ scale rows between dorsal-fin origin and ventral midline in front of pelvic-fin base; 12 circumpeduncular scale rows; 7–11 gill rakers on first gill arch.

References

1. Kottelat, M., 1996 - Raffles Bulletin of Zoology 44(1): 301-316
   The identity of Puntius eugrammus and diagnoses of two new species of striped barbs (Teleostei: Cyprinidae) from southeast Asia.
2. Kottelat, M., 1992 - Raffles Bulletin of Zoology 40(2): 187-192
   The identity of Barbus johorensis Duncker, 1904 (Teleostei: Cyprinidae).
3. Kottelat, M., 2013 - The Raffles Bulletin of Zoology Supplement 27: 1-663
   The fishes of the inland waters of southeast Asia: a catalogue and core bibiography of the fishes known to occur in freshwaters, mangroves and estuaries.
4. Kottelat, M. and H-H. Tan, 2011 - Ichthyological Exploration of Freshwaters 22(3): 209-214
   Systomus xouthos, a new cyprinid fish from Borneo, and revalidation of Puntius pulcher (Teleostei: Cyprinidae).
5. Pethiyagoda, R., 2013 - Zootaxa 3646(2): 199
   Haludaria, a replacement generic name for Dravidia (Teleostei: Cyprinidae).
6. Pethiyagoda, R., M. Meegaskumbura, and K. Maduwage, 2012 - Ichthyological Exploration of Freshwaters 23(1): 69-95
   A synopsis of the South Asian fishes referred to Puntius (Pisces: Cyprinidae).
7. Tan, H-H. and M. Kottelat, 2009 - Ichthyological Exploration of Freshwaters 20(1): 13-69
   The fishes of the Batang Hari drainage, Sumatra, with description of six new species.