Glass catfish

The glass catfish (Kryptopterus vitreolus) is one of the most remarkable freshwater aquarium species — its body is almost entirely transparent in life, revealing the spine and internal organs through a translucent musculature and skin. Endemic to coastal river basins of Peninsular Thailand and the Cardamom Mountains in southeastern Thailand, this species was only formally described in 2013 after decades of misidentification as Kryptopterus bicirrhis or K. minor. It reaches a modest 5.5–6.5 cm in standard length and is distinguished by its nearly invisible body, forked caudal fin, and two long sensory barbels extending forward from the snout.

Glass catfish are highly gregarious and must be maintained in groups of six or more to thrive; solitary individuals become stressed, lose condition, and typically perish prematurely. They are peaceful but somewhat timid, making them unsuitable tankmates for boisterous or aggressive species. Ideal companions include small, peaceful Southeast Asian species such as Trigonostigma harlequin rasboras, Boraras micro-rasboras, and various small loaches. In nature they are micropredators feeding on small invertebrates and zooplankton, and in the aquarium they should be offered daily meals of small live or frozen foods such as Artemia nauplii, Moina, and microworm, though they will also accept high-quality dried foods of a suitable size.

A biologically mature aquarium with base dimensions of at least 90 × 30 cm (roughly 80 liters) is the minimum for a small school. They prefer subdued lighting with surface vegetation or floating plants, and the addition of dried leaf litter and alder cones is beneficial for mimicking the blackwater conditions of their natural habitat. Recommended water parameters include a temperature of 20–26°C, pH 4.0–7.0, and hardness of 18–179 ppm. They are sensitive to swings in water chemistry and should never be added to an immature or unstable aquarium. This species has never been bred on a commercial basis, and all specimens in the trade are wild-caught from its relatively restricted Thai range.