Nandus nandus is an ambush predator from South Asia that masterfully mimics a dead leaf. A strictly carnivorous species for experienced fishkeepers.
Overview
Nandus nandus, known as the Gangetic Leaffish or simply Nandus, is one of the most unusual freshwater predators available in the aquarium hobby. This member of the family Nandidae (leaffishes) inhabits waters across India, Bangladesh, Nepal, Myanmar, and Thailand, primarily in the Ganges river basin and surrounding drainage systems. The fish occupies slow-moving rivers, ponds, flooded plains, and canals with dense vegetation and abundant leaf litter.
The most remarkable feature of Nandus nandus is its striking mimicry. The body shape, coloration, and behavior make it virtually indistinguishable from a dead leaf drifting in the water column. The fish can change its color to match its surroundings, ranging from light brown to dark marbled brown. Motionless among plant debris, the predator waits for prey, then strikes with lightning speed using its large protrusible mouth. This extendable mouth allows Nandus nandus to swallow prey nearly its own size.
Adults grow to 10–15 cm in length and live 5–8 years in captivity. While the overall care level is moderate, the species' specific dietary requirements and predatory nature make it a choice strictly for experienced aquarists.
Tank Requirements
Nandus nandus requires an aquarium of at least 100 liters. Optimal water parameters are: temperature 22–28°C, pH 6.5–8.0, and hardness GH 8–18. The species is fairly tolerant of a wide range of parameters, reflecting the diversity of biotopes across its natural range.
The aquarium should be set up to closely replicate the natural habitat of this ambush predator. Dense plant growth, driftwood, fallen leaves (oak or Indian almond), and subdued lighting are essential. Leaf litter on the bottom not only creates a natural atmosphere but also serves as camouflage, allowing the fish to exhibit its hunting behavior. Multiple hiding spots made from roots and stones will help reduce stress.
Water flow should be gentle or moderate, as these fish inhabit still or slow-moving waters in the wild. Good filtration is important for maintaining water quality, but the outflow should be diffused to avoid strong currents.
Feeding and Diet
Nandus nandus is a strict carnivore, and this is the key consideration before acquiring one. In the wild, it feeds on small fish, shrimp, insect larvae, and other invertebrates. In the aquarium, the diet should consist of live and frozen foods: bloodworms, glassworms, small shrimp, earthworms, and appropriately sized live fish.
It is important to understand that most specimens categorically refuse dry and pelleted foods. Some individuals may eventually accept frozen foods, but counting on a transition to prepared feeds is unrealistic. Before purchasing, make sure you are prepared to provide live and frozen food on a permanent basis.
Thanks to its protrusible (extendable) mouth, Nandus nandus can swallow surprisingly large prey — fish only slightly smaller than itself. This must be taken into account when selecting tank mates. Adult specimens should be fed 3–4 times per week, as predators in the wild do not eat daily.
Care and Maintenance
Keeping Nandus nandus requires attention to water quality and parameter stability. Weekly water changes of 25–30% are mandatory. Ammonia and nitrite levels must be maintained at zero, and nitrates should not exceed 20 mg/l. Despite the moderate care level, the fish is sensitive to sudden changes in water parameters.
The Gangetic Leaffish is primarily diurnal, though it is most active during twilight hours at dawn and dusk when it hunts. For most of the day, the fish remains motionless, camouflaged among the decor. This is perfectly normal behavior and should not cause concern.
It is essential to equip the aquarium with a secure lid, as Nandus nandus can jump out of the water. Regularly check the condition of hiding spots and plants to ensure the environment remains comfortable and as close to natural conditions as possible.
Compatibility
Nandus nandus is an aggressive predator (behavior level 4 out of 5), and selecting tank mates requires extreme caution. The cardinal rule: any fish that fits in its mouth will be eaten. Given its ability to swallow large prey, avoid keeping it with any small or medium-sized species.
Suitable tank mates include large peaceful or semi-aggressive species: large angelfish, large barbs, climbing perch, and medium-sized catfish. Keeping it with small tetras, livebearers, small barbs, or shrimp is strongly discouraged — all of these will become food for the predator.
A group of several Nandus nandus can be kept together provided the aquarium volume is sufficient and there are plenty of hiding spots. Territorial conflicts may occur if space is limited. The optimal setup for a species tank is a group of 3–5 individuals in a tank of at least 200 liters.
Breeding
Breeding Nandus nandus in captivity is a challenging task (difficulty level 4 out of 5) that only experienced aquarists tend to achieve. Sexual dimorphism is subtle: males are typically slightly larger and more vividly colored during the spawning period.
To stimulate spawning, gradually raise the water temperature to the upper end of the range (27–28°C), increase water change frequency, and provide generous feedings of live food. Spawning usually takes place on flat surfaces such as rocks, broad plant leaves, or driftwood. The female lays between 100 and 300 eggs.
The male assumes responsibility for guarding the clutch and becomes markedly aggressive toward any approaching fish, including the female. It is best to remove the female after egg laying. Incubation lasts 3–4 days, after which the larvae begin free-swimming within a few days. Starter food for fry includes brine shrimp nauplii and microworms. As the fry grow, they should be transitioned to larger live foods. Cannibalism among juveniles is possible, so regular size-sorting is necessary.