Fish, Tanks and Ponds

Fish, Tanks and Ponds
A comprehensive guide to fish

Monocirrhus polyacanthus

Leaf fish

Leaf fish, Monocirrhus polyacanthusLeaf fish, Monocirrhus polyacanthus
Photos by Michelle Stuart


Greek, monos = one.
Latin, cirrus = curl

Refers to the single barbel.

General Notes:

Monocirrhus polyacanthus are very sensitive to poor water quality. Because they produce a lot of ammonia due to their protein rich diet it is important that their aquarium is equipped with excellent filtration and that a good maintenance regime is adhered to.
Very soft acidic water is mandatory for this sensitive species which presents a few problems of its own because very soft water is always at risk from a sudden drop in pH unless the dGH is carefully monitored daily.
Monocirrhus polyacanthus is a very nervous species so careful consideration should be taken when siting the aquarium.
Monocirrhus polyacanthus should be kept in a well planted aquarium with bogwood providing some hiding places and creating some shady places where the fish feels more comfortable, dense planting will also help to filter out some of the light.


Carnivore, most individuals will only accept live food. Juvenile fish will accept live aquatic inverts but older specimens may only accept live fish. In the UK it is illegal to use live vertebrates as food.
It is sometimes possible to train the fish to accept dead prey but this can be time consuming and success is not guaranteed.


Predatory but peaceful with fish which are too big to swallow whole. Does best when kept in a species tank.


Very difficult, females appear more rounded when coming in to breeding condition.


Aquarium breeding has been accomplished, a rise in both temperature and pH will help to trigger spawning in a well conditioned and compatible pair. As many as 300 eggs could make up a single brood. The adhesive eggs are normally laid on the underside of a large leaf. After spawning the male assumes the dominant role in caring for the brood and the female should be removed from the breeding tank.
The fry will begin free swimming after about 60 hours (temperature dependent). Once all the fry are free swimming the male too can be removed from the breeding tank.
The fry will take freshly hatched brine shrimps immediately and they will consume a surprising amount. The fry will grow quickly but the growth rate may be uneven and unless graded and separated the larger fry will prey on their smaller siblings. Don't try to raise to many fry to adulthood. Monocirrhus polyacanthus are very specialised fish with limited appeal to the majority of fish keeping hobbyists which means that you may end up being stuck with the fry for quite some time.

Wild status

Monocirrhus polyacanthus has not been evaluated by the IUCN Redlist of endangered sspecies.

Additional information

Acidic water inhibits the growth of pathogenic bacteria, in harder more alkaline conditions these bacteria flourish and Monocirrhus polyacanthus is not equipped to deal with this. Unless the fish is kept in very soft acidic conditions it is likely to fall victim to various opportunistic infections which will eventually lead to its early demise.

Information at a glance

pH: 5 - 6
dGH: 2 - 6
Temperature: 22 - 25°C (72 - 76°F)
Diet: Carnivore
Size: 8cm (3.25in)
Min tank size: 100 litres
Difficulty level: Very difficult
Aquarium type: Species
Swimming level: All levels

Distribution and habitat

distribution map for Leaf fish, Monocirrhus polyacanthus

Origin: South America: Amazon River basin

Habitat: Shallow static water among leaf litter.


Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Polycentridae
Genus: Monocirrhus
Species: M. polyacanthus, Heckel, 1840

Other common names:
Barbeled leaf fish

Monocirrhus mimophyllus