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South American Leaffish Fish Breed Profile

Thomas R. Reich PhD

The unique South American Leaffish is a very interesting fish for the classroom or for the collector with many aquariums that wants a conversation piece. It is, however, a challenging pet to own—and it can be expensive as well. If you commit to owning one of these remarkable and rare fish, understand the commitment you are making and fully embrace the challenge of a truly unusual fish.

Characteristics

Scientific Name Monocrrhus polyacathus heckel
Synonym Monocirrhus mimophyllus
Common Name

South American Leaffish

Family Nandidae
Origin Amazon and Reo Negro Basins; British Guiana.
Adult Size 3 inches
Social Aggressive
Lifespan 5-8 years
Tank Level All
Minimum Tank Size 20-25 gallons
Diet Carnivore
Breeding Egg layer
Care Moderate to difficult
pH 6.0-6.5
Hardness 2-4 dH
Temperature 77-82°F (25-28°C)

 

Origin and Distribution

The South American Leaffish hails from the Amazon River basin in the countries of Peru, Brazil, Bolivia, Columbia, and Venezuela. It lives in shallow water where it hides in the vegetation in the riverbed, facing downward. Hidden from its prey by its surroundings, its camouflaged body, and its transparent fins, these fish are nearly undetectable until it attacks.

Colors and Markings

The South American Leaffish looks extraordinarily like a dead leaf, floating among the vegetation toward the bottom of a tank. Like a leaf, it is small, oval-shaped, and flat. It has a huge mouth relative to its size; its lower jaw features a pointed extension. Both its anal and dorsal fins are made up of spines. Under most circumstances, this fish is orange-yellow or brown with random markings as well as three lines running from the eye to the belly, from the mouth to the caudal fin, and from the eye to the dorsal fin.

The most impressive and interesting aspect of the South American Leaffish is its uncanny ability to camouflage itself while lying in wait for prey. Its colors may change in order to fit in more perfectly with its background, whether in the wild or in captivity.

Tankmates

The South American Leaffish gets its name because it looks remarkably like an actual dead leaf.

  It looks this way because it is an ambush predator, lying in wait of any prey it can fit in its very large mouth. This fish can eat its weight in live fish every day.  Even though it is only about 3 inches full grown, it can clean out your community aquarium in a week.   In order for this fish to be kept alive, each fish must be fed at least 3 grown guppies per day, or they will quickly weaken and die. Bottom line: It is best to keep this species on its own. If you do want to include other fish in the tank, choose larger, more robust and aggressive species such as the Armored Catfish or medium-sized loricariids.

South American Leaffish Habitat and Care

To thrive, the South American Leaffish needs soft water and dim light. Floating plants can also help to recreate the fish’s natural habitat and keep harsh light from filtering down. Because this fish hunts in ambush and is easily frightened, it also needs plenty of large-leafed plants, driftwood, and other hiding places. Water in the tank should be as still as possible.

South American Leaffish Diet

Leaf Fish do well in an aquarium, but they prefer to eat live fish as their main diet.  Guppies are eagerly eaten, but this can be costly food.

  In some places, like the southern states, there is an abundance of small native fish that can be caught and fed to the Leaf Fish.

Sexual Differences

There are few differences between males and females, though females will appear plumper during spawning season. The male also has slightly larger fins.

Breeding of the South American Leaffish

This species is not particularly difficult to breed; the challenge is not so much providing special conditions, as it is the luck of finding a pair that happens to be ready to breed. If they are ready to breed and there is a broadleaf plant such as an Amazon sword plant, they will lay eggs on the underside of the leaf.  The eggs will be tended to closely by both parents and hatch in 3-5 days.

Leaf Fish are good parents.  Eggs are usually deposited on the underside of a living leaf or on a stone, After the fish give much affectionate attention to each other, the female carefully deposits her eggs and the male fertilizes them.

  Each egg is attached to the leaf or stone by a short thread.  Hence, the large glassy eggs are all raised slightly off the spawning site.

The male leaf fish stays close to the eggs, carefully fanning water over the eggs.  They hatch in about two or three days, but the babies remain attached to the spawning site by the egg thread for another week.  Once they are free-swimming, baby leaf fish act much like their parents, remaining still most of the time.  At first, young leaf fish eat small aquatic animals, but by the time they have grown to a half inch, they are able to eat small fish the size of baby guppies.

The fry (baby fish) are transparent for about 2 weeks and will graze on infusoria that exists on mature plants and rocks in the aquarium.  After 2 weeks the fry should be removed and separated since they grow at different speeds, and larger fry will eat smaller fry as soon as they can fit the smaller fry in their mouths.

The fry must be fed plenty of daphnias, mosquito larva, and if available, guppy fry for fastest growth.  The fry are covered with white specks up until about 2 months of age, it looks like they have Ich, but this is just natural coloring for fry of this age.  After 2-3 months the fry will color up and be ready to eat larger fish, at this point they must be separated further.

Camouflage and the Amazon Leaf Fish

The Leaf Fish is a superb camouflage artist.  With colors varying from dark brown to gray, it drifts aimlessly through the water looking remarkably like one of a million real leaves in the stream.  So good is its camouflage that even in a net with assorted dead leaves and twigs, it is likely to be returned to the water unseen—unless it moves.

Dark coloring is only one in a whole bagful of camouflage tricks of the leaf fish.  The body, with its margin of jagged fins, is a perfect leaf outline.  From the eye radiate several dark lines resembling the veins of the leaf.  Many leaf fish have a quarter-inch-long flap of skin protruding from their lower lip that looks much like the stem of a leaf.

To complete the deception, the only fins that normally move, the pectorals and the rear tips of the dorsal and anal fins, are transparent, nearly invisible when in motion.

Further, leaf fish frequently swim at an unfishlike head-down angle.

While this clever camouflage gives the three-inch leaf fish wonderful protection from larger predatory fish, the main value of the camouflage is as an aid in capturing smaller fish.  The leaf fish may drift with the current until an unsuspecting smaller fish swims near, or it may sidle ever so slowly up to a fish until its mouth is almost touching.

Then, in a lightning-fast motion, the lower jaw swings down, and an unbelievably huge tube-like mouth unfolds and swings out, creating a suction that draws the unsuspecting victim in.  With a gulp, the hapless fish is gone.  Fully extended, the mouth is as long as the fish’s head.  Occasionally, the Leaf Fish extends its cavernous mouth for no apparent reason, as if it were yawning out of boredom.

More Pet Fish Breeds and Further Research

If you’re interested in similar breeds, check out:

  • Pirhana Fish Breed Profile
  • Neon Tetra Fish Breed Profile

Otherwise, check out all of our other freshwater pet fish breed profiles.

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