Swamp Eel

Ophisternon bengalense belongs to the Synbranchidae, the swamp eels, an order of truly eel-like fish that have lost all fins except for tiny vestigial remnants in some species. Found across South Asia in slow rivers, swamps, and flooded rice paddies, it breathes air through a bimodal respiratory system and can survive extended periods in moist soil.

In the aquarium it requires a very soft sandy or muddy substrate into which it can completely bury itself. The tank must have an absolutely secure lid as this species is capable of squeezing through very small gaps. It should be fed exclusively on meaty items: live and frozen bloodworm, earthworms, and small prawns are all consumed avidly.

This is a solitary and somewhat territorial species best kept individually or in large aquariums where individuals can establish separate burrow territories. Its fascinating biological adaptations and snake-like appearance make it a rewarding species for advanced oddball keepers.

Water: Soft, pH 6.0–7.8, temperature 22–28°C, GH 2–12, KH 1–6. Tank: Minimum 150 L, deep soft substrate, completely sealed lid, minimal decoration. Feeding: Carnivore; bloodworm, earthworms, tubifex, small prawns. Breeding: Not achieved in captivity; air-gulping courtship behaviours observed. Compatibility: Solitary; avoid all small fish and invertebrates.