Peacock Eel / Spot-finned Spiny Eel

Geographic Origin and Biotope: Widely distributed in Southeast Asia (Mekong, Chao Phraya basins). Inhabits slow-moving rivers, canals, and flooded forests with muddy or sandy substrates and dense vegetation.

Taxonomy and Morphology: Mastacembelidae (spiny eels). Not a true eel. Reaches 25-30 cm. Possesses free erectile dorsal spines. Long, fleshy, sensitive snout with tubular nostrils used to probe the substrate for food in the dark.

Social Behavior: Peaceful, shy, strictly nocturnal. Spends the entire day completely buried in soft substrate, leaving only the tip of its snout and eyes exposed. Emerges at dusk to hunt. Can become tame and hand-feed.

Coloration and Sexual Dimorphism: Light olive-brown body with a thin yellowish lateral band. Unmistakable feature: 3-6 striking black, yellow-rimmed ocelli (false eyes) along the dorsal fin base ('peacock' spots) to confuse predators. Mature females are noticeably plumper.

Tank Setup: 150+ liters (100+ cm length). TIGHT-FITTING LID: a master escape artist that slithers through heater cable holes at night. SUBSTRATE IS VITAL: deep, ultra-fine sand (no sharp quartz or gravel) is required for burying without scratching its delicate skin. PVC tubes, dim lighting.

Feeding: Benthic micro-predator. Feed at dusk/night: live earthworms (absolute favorite), frozen bloodworms, mysis, chopped shrimp. Categorically refuses dry flakes or pellets. Live earthworms are often the key to getting new arrivals to eat.

Water Quality: Clean freshwater, adaptable: pH 6.5-7.5, GH 5-15, 24-28°C. Slight salt additions are sometimes used to prevent fungal skin infections, but it is not a true brackish fish. Zero ammonia tolerance.

Compatibility: Excellent community fish for medium-sized companions (Gouramis, large Rasboras, peaceful Barbs). Avoid tiny fish (under 3 cm) which might be eaten at night, and aggressive bottom feeders that outcompete it.

Reproduction: Very rare in captivity without hormones. Sticky eggs scattered in floating plant roots during surface chases.

Risks: Escape and drying out on the floor is risk #1. Bacterial skin infections from sharp gravel scratches is risk #2 (fatal without sand). 'Scaleless' fish, highly sensitive to aquarium medications (copper, malachite green) — use half doses cautiously.