Glass Catfish

Geographic Origin and Biotope: Endemic to Thailand (Mae Klong River and Malay Peninsula). Lives in slow-flowing streams and swampy blackwater rivers (peat swamps), densely covered by vegetation.

Taxonomy and Morphology: Glass Catfish (Kryptopterus vitreolus). Historically often confused with K. minor or K. bicirrhis. It has an exceptionally laterally compressed and totally scaleless body, with two long maxillary sensory barbels.

Social Behavior: Peculiar "mid-water" behavior. Unlike almost all siluriforms, it constantly swims in cohesive schools (mandatory minimum 6, ideal 10+) undulating obliquely against the current.

Coloration and Sexual Dimorphism: Totally Transparent. Only the tiny silver sac of the internal organs behind the head and the entire white spine/bone are visible. No obvious external sexual dimorphism.

Aquarium Setup: Absolutely requires plant cover. Widely planted tanks with shaded areas generated by floating plants or large ferns (Microsorum). In bare or brightly lit tanks they die of pure stress in a few days.

Diet and Feeding: Insectivore Micro-predator. Often rejects flakes. Requires very small live or frozen food that floats in the water (Daphnia, Moina, Artemia or Grindal). Does not go down to eat on the bottom.

Water Quality: Very sensitive to medications and ammonia accumulation. Being scale-less, it absorbs toxins very quickly. Always filtered, slightly acidic or neutral water with moderate current.

Compatibility and Tankmates: Extremely peaceful but very shy fish. Do not mix with frenetic or aggressive species (Barbs, large Cichlids, fast Danios). Excellent with Rasboras, small Anabantids (peaceful Colisa, Betta), and Pangio kuhlii.

Aquarium Reproduction: Extremely rare and not sufficiently documented at the amateur level. Probably linked to the simulation of the monsoon season with sudden changes of fresh water.

Risks and Diseases: Lethal clouding. When a Glass Catfish falls seriously ill or is dying, its body loses its transparency becoming "milky" (opaque and white). An opaque fish is hardly salvageable.