ASIAN SWAMP EEL (Monopterus albus)

The Swamp Eel has a widespread distribution, from India eastwards to Japan, and south to Indonesia and Australia. Here, it is found in a variety of different tropical and subtropical habitats, from canals, ditches, estuaries, lowland wetlands, ponds, rivers, streams, and swamps. These waters range from flowing to stagnant, and, this resilient fish - which is capable of air breathing - can survive dry periods by burying deep into moist soil, or, if necessary, it can even travel short distances across land to find more suitable surroundings. This is a nocturnal species that preys on crustaceans, insects, small fishes, worms, and other small aquatic animals overnight, and has even been known to take turtle eggs. The aquarium should be voluminous with a soft sandy substrate and a tight fitting, heavy hood, with no gaps left where equipment feeds into the tank (holes can be blocked tightly with oversized chunks of filter sponge). The tank should be at least long enough for the fish to stretch out fully if it chooses to, and for it to make turns with ease. It is important to ensure the aquarium is escape-proof as these fish are proficient escape artists and could potentially travel quite some distance. Provide an abundance of shady hiding places amongst driftwood, smooth rocky crevices, robust planting, and wide PVC pipes. Due to the large adult size, predatory feeding habits, and somewhat cantankerous nature, this is a fish that is best kept alone. Monopterus albus is not actually a true eel in the strictest sense. It is a Synbranchid, characterised by only having one gill opening (which facilitates oxygen exchange from the water), located on the bottom of the throat, and an absence of swim bladder and ribs. It also has no covering of scales and lacks pectoral and pelvic fins. The anal, caudal, and dorsal fins are rudimentary, reduced to skin folds. Unlike most air-breathing fish, M. albus lacks a distinct air-breathing organ, and relies on extra-branchial gas exchange using a highly vascularised epithelium (tissues that line the outer surface of blood vessels) in the buccopharyngeal cavity, as well as a vascularised oesophagus and integument (skin). The buccal cavity expands during air-breathing, remaining initially inflated during submergence, with exhalation occurring either under water or at the surface prior to the next inhalation. To sum up: this is an unusual, specialist fish for the large oddball connoisseur, but please make sure all its long-term care requirements can be met prior to purchase.

Feeding

Juveniles can be offered bloodworm, vitamin-enriched brineshrimp, Mysis shrimp, and chopped krill. Adults should be offered larger foodstuffs such as cockles, earthworms, mussels, prawns, silversides, whitebait etc.

Breeding

This species has not been bred in the home aquarium. In the wild, the male constructs a floating bubble nest amongst surface vegetation close to the shore. As the eggs are laid/fertilised, the male picks them up and places them into the safety of the floating nest. Eggs may number several hundred, and it is the male who guards them. All fry are female initially, with a certain percentage of mature fish changing sex to male. In the event of a shortage of females, male fish can revert to female once again.