Monocirrhus polyacanthus – Amazon Leaffish
The Amazon Leaffish was first described by Heckel in 1840 after this species was discovered by Johan Natterer. Only in 1912 did the first living specimens come to Europe.
The name polycanthus means spiky and refers to the spines on the dorsal and anal fin.
Monocirrhus polyacanthus is definitely not a fish for beginners. They are difficult to keep healthy and have specific requirements for the aquarium. So read well before you proceed to purchase this species!
If you can find the Amazon Leaffish in a well-decorated biotope aquarium, you must know what to look for. This species is almost impossible to find among dead leaves. Not only the color matches their environment, but the shape is perfectly adapted to it. To keep a perfect camouflage in the different environments, they can adjust their color slightly to the background.
The shape of the fish looks like a dead leaf. The dorsal and anal fin have spines, just like the serrations of a leaf. Under their chin they even have a protrusion that looks like the stem of a leaf. The difference between males and females is very difficult to see. The female is a bit fatter when she is full of eggs. The females also usually grow a little taller to about 10 centimeters total length where the males reach a maximum of about 8 centimeters.
You can describe the character of the Amazon leaffish as shy and passive. They hang motionless in the water near the surface and try to imitate a leaf as much as possible. Even when they swim, they imitate a gently floating leaf and use the miniscule transparent fins for moving around.
Due to the calm nature of the Monocirrhus polyacanthus it is better not to keep them together with larger, fast fish. These fish will certainly suppress the leaf fish. Stressed leaf fish will not last long in an aquarium. If you still want to keep other larger fish, you could consider Discusfish or Angelfish, but a special aquarium is of course even better. The life expectancy of the Amazon Leaffish is around 8 to 9 years.
Monocirrhus polyacanthus occurs in the wild in the slow-flowing parts of the Amazon. They are located in places where they do not stand out with leaves hanging in the water or leaf litter. They are completely absorbed in their environment.
The water in this environment is acid with a pH around 5 and a low hardness. The temperature is somewhere around 23 to 26 degrees Celsius.
Monocirrhus polyacanthus is a true hunter. The adult animals really only eat live food. Because a leaf fish eats a lot a day, up to its own weight, it is necessary to keep a large breeding tank of feeder animals. These can be fishes, but also shrimps for a change. Young animals sometimes take live mosquito larvae, but adult animals usually ignore them. Do not use goldfish as feeders, the scales of the goldfish are relatively large and can cause problems with digestion.
To blend in completely with its surroundings, Monocirrhus polyacanthus adapts its color to the surroundings. With his head down, he seems to be slowly drifting towards his prey. With its head down and the bulge on its chin that looks like a leaf stalk, it is just like a leaf floating in the current. As soon as its prey comes within reach, the Amazon Leaffish protrudes its mouth with lightning speed. This creates a sucking effect through which the prey is sucked in. The movement is so fast that it is almost invisible.
Because Monocirrhus polyacanthus is a very slow swimmer, it can be kept in an aquarium from 80 centimeters in length. In that case, I recommend a special aquarium without other fish as other fish quickly become food. Larger fish can be kept in larger aquariums, as long as they are very calm and swim slowly. Think of Angelfish, Discusfish, Climbing bass and on the bottom large Corydoras species or species from the Loricariidae family.
Decorate the aquarium with preferably large-leaved plants and large pieces of wood. The Amazone leaffish swims quietly in between or lingers between them looking for food.
The light may be slightly dimmed. You can also achieve this by using floating plants. Darkening the aquarium can also be achieved by filtering through peat. This has the additional advantage that it lowers the pH. The water values of the aquarium may be between pH 5 and 6.5 and a low hardness up to a maximum of GH 4. So you will often have to work with osmosis or rain water and filter over peat. The peat also helps to keep the fish healthy. They are very susceptible to diseases if the water composition is not good or contains too much waste.
The natural environment of the Monocirrhus polyacanthus consists of fairly stagnant to very slowly flowing water. Too much current is therefore not appreciated.
Breeding Aquarium and Conditioning
The Amazone Leaffish can be properly reproduced in a special aquarium described above. Preferably keep them together as a couple without other fish. It is important that the pH of the water is lower than pH 6.0 because the eggs usually do not hatch in a pH above 6.0. Females are already sexually mature with a length of 4 centimeters. The miniscule laying tube becomes visible from this length, you will have to make an effort to see the laying tube with small fish.
As soon as Monocirrhus polyacanthus are ready to spawn, the colors of the male become more intense. The laying tube becomes visible with the female. The couple are swimming on the surface next to each other, where the male touches the females body. They can show this behavior for a long time (from an hour to a few hours). As soon as the female is ready, she deposits her eggs at the underside of a large leaf. The male immediately fertilizes the eggs. The eggs hang on a thread on the leaf. The female will deposit up to 300 eggs.
The females job is done now. It is best to remove her now. The male can turn against the female after depositing to protect the eggs.
Rearing Monocirrhus polyacanthus fry
The male guards the eggs and fans them with his fins. The Monocirrhus polyacanthus eggs hatch after about 3 to 4 days. This is the time to also remove the male. The fry do not yet resemble a leaf fish. They have a blunt snout and only a developed caudal fin. The first few days they still live on their egg yolk sac.
Once the egg yolk sack has been used up, you can start feeding them. The young Amazon Leaf fish only eat live swimming food. You can start with freshly hatched brine shrimp. As the fry grow, you can feed them with increasingly larger food such as young fish. After about two months the fins are fully developed and the head gets the characteristic point. Ensure a sufficient supply of suitable food. The young leaf fish eat an enormous amount for their size.
You will see that there is a difference in development as they grow. A number of fishes grow faster than the rest. The larger ones will consider their smaller brothers and sisters as food. If you want to keep the entire group you have to separate them into different aquariums.
The water must be extremely clean, especially with the growing young. If the water isn’t pristine you will lose a lot or all fry. Therefore frequently change small amounts of water and try to prevent fluctuations in water composition.
The Amazon Leaffish is only suitable for the advanced aquarist who is prepared to meet the needs of this beautiful fish species. They are a very special species that show an interesting behavior!
John de Lange
J. de Lange