Borneo Sucker
Gastromyzon ctenocephalus
Gastromyzontidae
About
The Borneo Sucker is a small, disc-flat hillstream loach from the fast, cool, oxygen-saturated streams of western Borneo. Almost all trade stock arrives labelled "Gastromyzon sp." or under the older trade name Gastromyzon punctulatus, but the fish actually exported is overwhelmingly Gastromyzon ctenocephalus — described by Roberts in 1982 and sold under the wrong name for decades afterwards. What finally sorted the trade out was Tan's 2006 revision of the Borneo torrent loaches, which lifted the genus from five recognised species to thirty-six: true G. punctulatus reaches the hobby very exceptionally if at all, and what shops sell as it is this fish or the near-identical G. scitulus, with intermediate forms common even within a single import. A shop tank labelled Gastromyzon is honestly best treated as the traded group rather than one confirmed species — the husbandry below holds across all of them. It is small even by hillstream standards: 35-40 mm standard length is the usual maximum and 4.5 cm the largest on record, so the 5 cm on most shop labels is a rounded-up total length rather than a fish you should plan around. The flattened underside and enlarged, fused pectoral and pelvic fins form a suction disc that lets the fish hold station on smooth rock in full current while it rasps algae and biofilm. This is not a decorative beginner fish: it needs strong flow, near-river oxygen levels and a mature tank whose stones already carry a grazing film.
Care
Tops out around 4.5 cm, so a 60x30 cm base is enough room for a group — but the flow is not negotiable: 10-15x turnover, cool well-oxygenated water at 20-24°C and smooth, algae-covered stones. Keep four or more and feed vegetable-based foods rather than protein.
Diet
Aufwuchs grazer that rasps algae and biofilm from rock; supplement with algae wafers, blanched vegetables and spirulina, and only occasional small amounts of frozen bloodworm — excess protein causes digestive problems.
Tankmate compatibility
Gets along with (31)
Possible with care (128)
Avoid (112)
Computed by the AquaSage engine for a spacious reference tank — always check the full verdict for your exact setup in the calculator.
Telling males from females
What works for this species, most reliable first.
- Adult sizeA hint only · only across animals of the same age
In many cichlids, catfish and loaches one sex simply grows larger — usually the male, though there are well-known reversals.
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Frequently asked questions
- What tank size does a Borneo Sucker need?
- A Borneo Sucker needs an aquarium of at least 60 litres (15.9 US gallons) with a footprint at least 60 cm (23.6 in) long — for this species, swimming length matters as much as raw volume.
- What water parameters does a Borneo Sucker need?
- Borneo Sucker does best at 20–24 °C (68–75.2 °F), pH 6–7.5 and a general hardness of 2–12 °dGH.
- What group size does a Borneo Sucker need?
- Borneo Sucker is a social species — keep a group of at least 4 so natural behaviour emerges and stress stays low.
- Is the Borneo Sucker suitable for beginners?
- Borneo Sucker is a demanding species best attempted with some experience — it needs stable, closely watched conditions to thrive.