Chameleon fish

Geographic Origin and Biotope: Widely distributed in India, Bangladesh and Nepal (Ganges and Brahmaputra basin). Inhabits shallow and slow streams, ponds and ditches rich in marsh vegetation and dense algal carpets.

Taxonomy and Morphology: Blue Badis / Chameleon Fish (Badis badis). Belongs to the singular Badidae family (relatives of the Nandids). Has the morphology of a small ambush predator: stocky body, short snout but protrusible mouth, and a majestic continuous dorsal fin.

Social Behavior: Peculiar, shy but extremely territorial and possessive (especially males). Glides awkwardly on the bottom using its pectoral fins in jerks, maniacally inspecting caves. Not an active swimmer in the water column.

Coloration and Sexual Dimorphism: "Chameleon Fish" for good reason: males dramatically change color based on mood, going from pale mud to almost total blue/black, with reddish flanks and bright dots. Females remain perennially drab, pinkish-gray and with a more curved abdomen.

Aquarium Setup: Minimum 60 cm (24 inches) aquarium. Requires dense furnishing: a total tangle of woods, broken coconuts (excellent dens) and a lot of dense and shading vegetation. Dark sandy bottom. If the tank is bare, the fish will turn pale refusing to be seen.

Diet and Feeding: True scourge of beginners: categorically REFUSES dry food (flakes and granules). Feeds exclusively on live and frozen foods (bloodworms, tubifex, brine shrimp, daphnia). Furthermore, it is a voracious hunter of pest snails.

Water Quality: Sub-tropical fish. Prefers relatively cool waters (18-25°C / 64-77°F) and moderate hardness. Does not tolerate "discus" temperatures (>28°C / 82°F), in which it drastically shortens its life and suffers bacterial diseases.

Compatibility and Tankmates: Males clash harshly; better to keep a pair or one male with multiple females in medium tanks. Ignores surface fish (Rasboras), but relentlessly preys on Neocaridina zoeae (will devour any shrimp that fits in its mouth).

Aquarium Reproduction: Similar to "cave-spawner" cichlids. The male vigorously (and sometimes violently) courts the female, pushing her into the cave, where she lays the eggs "embraced" by him. Only the male guards the nest, brutally chasing everyone away.

Risks and Diseases: Starvation. The most frequent problem in the aquarium is death by starvation caused by the stubborn offer of dry feeds or by ruthless food competition (fast fish that steal the frozen food before the Badis reaches it on the bottom).