Peacock Eel / Spot-finned Spiny Eel

Geographic Origin and Biotope: Southeast Asia (Thailand, Mekong Basin, Malaysia). Lives in silty bottoms, rice paddies, swamps and canals with slow waters and a dense tangle of roots and rotting foliage.

Taxonomy and Morphology: Peacock Eel (Macrognathus siamensis). Medium-sized Mastacembelid. Possesses a serpentine anguilloid body ending in a pointed snout prolonged in a rostrum (fleshy proboscis) useful for probing the sand.

Social Behavior: Extremely fossorial and nocturnal. Spends much of the day entirely buried in the sand: only the rostrum (which acts as a snorkel) and the eyes emerge from the substrate, scanning the environment.

Coloration and Sexual Dimorphism: Brown/olive body topped by a golden line along the spine. The dorsal fin, joined to the caudal, presents from 3 to 6 yellow-ringed black ocelli (fake peacock eyes) to disorient predators.

Aquarium Setup: Minimum 120 cm (48 inches) aquarium. MANDATORY REQUIREMENT: thick layer (7-10 cm / 3-4 inches) of fine and absolutely non-sharp sand. Omit heavy furnishings resting on the sand, as its digging activities would cause them to collapse.

Diet and Feeding: Macro-invertebrate carnivore. Ignores flake feeds and struggles to accept dry pellets. Must be fed in the evening (in the dark) with frozen bloodworms, earthworms (chopped) and mysis. Uses the rostrum to flush out buried prey.

Water Quality: Requires clean water but without excessive current. Can tolerate slight additions of salt (very weak brackish water) but thrives in fresh water. The tank lid MUST be totally sealed.

Compatibility and Tankmates: Peaceful with fish too large to be swallowed (Gourami, Loaches, medium-sized Barbs). Infallible predator of any fry, caridina (shrimp) or small spindle-shaped fish (e.g. Neons) during the night.

Aquarium Reproduction: Very rare in captivity without hormonal stimuli. Males chase females until they intertwine among floating vegetation, where they lay adhesive eggs. No parental care.

Risks and Diseases: Skin infections and Escape. If housed in tanks with coarse gravel or sharp quartz, it will flay its belly and proboscis, developing lethal fungal infections. Honorable mention: will escape from any lid hole wider than 1 cm (0.4 inches).