Borneo Sucker

Geographic Origin and Biotope: Endemic to Borneo (Malaysia and Indonesia). Populates only very fast mountain and hill streams ("hillstream"), rich in waterfalls and smooth boulders strongly illuminated by the sun, in cold and oxygen-saturated waters.

Taxonomy and Morphology: Borneo Sucker or Hillstream Loach (Balitoridae). Flat sucker fish. Hydrodynamic body, pectoral and pelvic fins fused together to form a suction disk capable of adhering to rocks in flooded rivers without being swept away. Measures barely 4 cm (1.5 inches).

Social Behavior: Peaceful, busy and territorial only for the best "grazing" stones. Spends its existence browsing the algal biofilm (aufwuchs) from the stones. Males engage in "fights" covering each other, but they never get hurt.

Coloration and Sexual Dimorphism: Camouflaged on the rocky bottom: dark or opaque black body with magnificent dense golden-yellow or white stippling. The fins are striped with intense blue/light blue on the edges. Females seen from above have a wider shape (guitar-shaped), males are more angular.

Aquarium Setup: Specifically requires a "Hillstream manifold aquarium": very strong unidirectional water pushed by wavemakers (flow 15-20 times the volume of the tank). Smooth gravel bottom and mountains of large bare river pebbles for algal development.

Diet and Feeding: Feeding is the critical point. They do not survive on dry flakes. Must have unlimited access to stones covered with slimy green algae and diatoms (to be cultivated separately). Supplement with frozen bloodworms, spirulina tablets or vegetable and fishmeal-based gel.

Water Quality: Very strict thermal tolerance: 20-24°C (68-75°F), strictly not over. Warm water reduces dissolved oxygen leading to suffocation. Neutral or acidic pH (6.0-7.5). Huge weekly water changes and impeccable filter maintenance (No3 < 10ppm).

Compatibility and Tankmates: Ideal companion for White Cloud Mountain Minnows (Tanichthys), Danios (Zebra, Pearl), other Balitorids (Sewellia, Beaufortia) and Stiphodon. Not recommended for all Amazonian or Asian slow warm-water fish, which would hate the violence of the flow and the cold.

Aquarium Reproduction: Difficult but possible in a dedicated setup with coarse gravel and gaps between the pebbles (where the eggs fall safe from the adults). Males dig nests in the sand near the stones and the tiny fry feed on microorganisms sheltered in the gravel.

Risks and Diseases: Wild-caught fish: they arrive chronically undernourished and parasitized. The use of medicines containing copper or malachite is deadly as they are scaleless fish. They die suddenly if placed in normal warm and oxygen-poor tanks (summer hypoxia).