South American lungfish (Lepidosiren paradoxa) - Tropical Fish for Sale UK

Overview

The South American lungfish is a genuine living fossil — an air-breathing giant whose lineage has drifted almost unchanged through more than 100 million years. Sinuous and eel-like, it hangs in the water like a length of living rope, rising every few minutes to gulp a fresh breath at the surface. This is not a community fish but a lifelong specimen for the dedicated keeper: it is enormous, remarkably long-lived and utterly unlike anything else in the hobby. Owning one is closer to keeping a small aquatic reptile than a typical tropical fish.

Appearance & Identification

The body is long, cylindrical and smooth, coated in a heavy protective mucus that gives it a slick, dark sheen ranging from slate-grey to olive-brown, sometimes flecked in juveniles. In place of ordinary pectoral and pelvic fins it carries slender, thread-like filaments that it uses to feel and “walk” delicately along the bottom. The eyes are small and the mouth wide. Mature adults are formidable, commonly reaching around one metre and occasionally 125 cm, so the fish you receive as a modest youngster will one day fill a very large system.

Aquarium Setup

Provide an oversized, long-footprint aquarium — 1,500 litres is a sensible minimum for an adult — with a soft sand bed, smooth rounded décor and no sharp edges. Filtration should be strong but gently returned, as this is a slow-water species. Keep the water warm at 24–30°C and soft to moderately hard at pH 6–7.5. Critically, the lungfish is an obligate air-breather: it must reach the surface to fill its paired lungs, so never seal the tank to the waterline, and always leave a clear, unobstructed air gap above the water.

Temperament & Tank Mates

Slow, deliberate and surprisingly placid toward anything too large to be seen as food, the South American lungfish is nonetheless a committed predator with a powerful bite. In practice it is best kept entirely alone. Tank mates small enough to swallow will simply disappear, and rival lungfish can be intolerant of one another. Its temperament is peaceful in the sense that it will not chase or harass — but everything it can fit in its mouth is treated as a meal.

Feeding

A carnivore through and through, the lungfish takes earthworms, prawn, mussel, cockle and other meaty items, along with sinking pellets formulated for large predators. It feeds slowly and deliberately, often mouthing food before committing, so allow plenty of time and remove anything uneaten. Two or three substantial meals a week suit an adult; juveniles can be fed a little more often. Vary the diet to keep it in strong condition.

Breeding

Breeding is essentially unheard of in home aquaria and demands conditions far beyond a normal tank. In the wild the male excavates a burrow and guards the eggs, developing richly blood-vesseled filaments on his pelvic fins that are thought to help oxygenate the developing young. It is a fascinating natural history but not a realistic aquarium project.

Delivery & Live Arrival Guarantee

Every South American Lungfish is hand-selected and quarantined before sale, then packed in oxygenated bags with insulation and heat packs when needed and sent by tracked, live-animal courier. Your order is covered by our Live Arrival Guarantee, so it reaches you safely anywhere in the UK.