- Scientific name: Monocirrhus polyacanthus
- Synonyms: Monocirrhus mimophyllus
- Common name: Leaf Fish, Amazon Leaffish, South American Leaf Fish
- Group: Other fishes
- Habitat: South America; Brazil, Peru, Venezuela, Colombia and Bolivia.
- Size: 10 cm
- Biotope: Inhabits in slow-flowing, shallow waters among the fallen tree leaves.
- Social behavior: Males can be very aggressive and territorial, and they can even kill each other. It is best kept in a single species set-up, but can be kept in a communtity tank with bottom dwelling fish, like medium-sized loricariids and armored catfish.
- Diet: Carnivorous; will only accept live foods. Juveniles will eat shrimps and small earthworms, but it is recommended to feed the fish with live feeder fish, such as livebearer fry, as small fish are their natural food.
- Breeding: Hard
- Tank: Minimum 70 litres
- Population: 1 pair for 70 litres
- Decoration: Floating plants are recommended as they diffuse the light, and use lots of broad-leaved aquatic plants such as Echinodorus species. Decorate the tank with roots to provide hiding places.
- Temperature: 22-25 °C
- pH: 5-6.8
- Hardness: 1-10NK°
- Lifespan: 5-8 years
Description: Leaf fish as its name suggests is resemble to a dead leaf, both in body shape and pattern. Monocirrhus polyacanthus can also change its color to match the surrounding environment. Their base color is orange-yellow to brown with dark markings: a transverse line runs through the eye to the belly, a second from the eye to the dorsal fin, and a third runs on the side of the fish from the mouth to the caudal fin. The fish has large mouth and a pointed lower jaw that resembles to a leaf stalk. The South American Leaf Fish is often hover in a vertical position, as in its natural habitat it stalks its prey in this head-down stance, mimicing a dead leaf. It approaches the prey using it's transparent pectoral fins which makes the fish almost undetectable. When it strikes the entire mouth sticks out, forming a large tube and easily sucks the small prey up. This is so quick that is often difficult to see. It can swallow prey almost as big as itself. Amazon Leaffish isn’t for begginers, as it is very sensitive to water quality, and require live foods.
The females are rounder especially during spawning. Breeding is possible in a home aquarium, arrange a tank with broad-leaved plants and fill it up with soft (1-5 dH), acidic (pH 6-6,5), warm (at least 25 °C) water. Use a single pair, and condition them with lots of live foods. During spawning the body color of the male is intensifying. The female Leaf Fish lays up to 300 eggs to the underside of a large leaf or overhanging rock and the male fertilize them. After spawning the male looks after the eggs, fanning them with his fins. Female should be removed at this point from the tank. The eggs hatch in 3-4 days and the male can alos be removed. After their yolk sacs are absorbed they can be fed with brine shrimp nauplii. The fry are greedy eaters and will consume their body weight in food daily. Later they should be fed with livebearer fry and other feeder fish. The young grow at different rates and periodically must be sorted according to size to prevent cannibalism.