FishFreshwaterIntermediate
©AI Generated·Proprietary
Amazon leaf fish
Monocirrhus polyacanthus
One of the most extraordinary ambush predators in fishkeeping: the compressed body, brown livery with veining, and small chin barbel perfectly imitate a dead leaf. Swims slowly at an oblique head-down angle, drifting with the current toward prey, which it inhales with a lightning-fast accordion-like mouth expansion — capable of swallowing prey up to 2/3 of its own length. For experienced aquarists only: requires live food (nearly impossible to adapt to frozen), acidic, pristine water, species-only tank. A pure observation species.
Water Temperature
25 - 28 °C
pH Value
5.5 - 6.5
Water type
Freshwater
Tank level
Middle
Adult size
8 cm
Minimum tank volume
>= 75 L
Minimum group
>= 1
GH
1 - 5 dGH
KH
1 - 2 dKH
TDS
25 - 95 ppm
Conductivity
39 - 148 uS/cm
Species description
Geographical Origin and Habitat: Amazon and Orinoco River Basin (Peru, Brazil, Venezuela). Exclusive to very slow swamps and "Blackwater" rivers saturated with dead lianas, fallen trees and decaying plant debris.
Taxonomy and Morphology: South American Leaf Fish (Monocirrhus polyacanthus). Mimetic evolution par excellence. The body is flat, perfectly leaf-shaped; it even has a rigid barbel on the chin that simulates the "stalk" of a dead leaf.
Social Behavior: Immobile ambush predator. Spends entire weeks floating upside down (obliquely) imitating a dead leaf moved by the current, waiting for a small unaware fish to approach.
Coloration and Sexual Dimorphism: Perfect camouflage: dry leaf brown or ochraceous yellow, with black mottling mimicking plant necrosis. Can lighten or darken to blend in with the decor. Sexes are indistinguishable.
Care, breeding and tankmates
Aquarium Setup: Extreme leaf biotope (Species Tank 80 cm / 32 inches). Lighting reduced to zero, peat in the filter, dark tea-colored water. Bottom covered with catappa/oak leaves and intricate twigs in mid-water.
Diet and Feeding: Obligate piscivore (Lethal starvation 1). Will ALWAYS refuse any dry or dead feed (even if waved with tweezers). MUST be fed daily with live feeder fish (Guppies, Neons) or live ghost shrimp (Caridina) that fit entirely into its extensible tube mouth.
Water Quality: Very delicate (Lethal starvation 2). Requires very pure water while tolerating organic nitrates (but zero ammonia). The marked acidity (Ph 5.5-6.0) protects its skin lacking resistant scales from deadly fungal infections.
Compatibility and Cohabitation: It is not a community fish. Must be alone or with other Leaf fish. Any fish under 4 cm (1.5 inches) will be inhaled. Any aggressive fish (or sucking pleco) will annoy it to death.
Aquarium Breeding: The male and female mate depositing transparent eggs (up to 300) under a broad leaf of Nymphaea. The male fiercely guards the eggs by fanning them.
Risks and Diseases: The ethical/economic nightmare. This fish is the despair of unprepared aquarists: it literally starves to death if you do not provide it with a constant and expensive supply of LIVE small bait fish every single day.
Geographic Origin and Distribution
Amazon and Orinoco River Basin (Peru, Brazil, Venezuela). Exclusive to very slow swamps and "Blackwater" rivers saturated with dead lianas, fallen trees and decaying plant debris.
Origin
Amazon, Orinoco, and Guianas
Fish profile
- Temperament
- Peaceful
- They have a lethargic, highly secretive, and perfectly methodical temperament. They are the ultimate ambush predators, relying entirely on their masterful camouflage to wait for prey to drift too close. They are fascinating to observe but require a highly dedicated aquarist willing to cater to their strict dietary and environmental needs.
- Diet
- Carnivore
- They are obligate piscivores that will almost exclusively only accept live fish as food. Weaning them onto frozen meaty foods like bloodworms is extremely difficult and often unsuccessful. A steady, safe, and disease-free supply of live feeder fish or live ghost shrimp is absolutely mandatory for their long-term survival.
- Life expectancy
- 5-8 years
- In captivity, *Monocirrhus polyacanthus* has a typical lifespan of 5 to 8 years when housed in a dedicated aquarium with pristine water quality. Their survival is heavily dependent on their highly specialized dietary needs, as they will refuse prepared foods and can starve if live feeder fish are not constantly available. Minimizing stress from water parameter changes and keeping them in a quiet environment are essential to help them reach their maximum age.
- Adult size
- 8 cm
- The catalog's scalar value is 8 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 8 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Monocirrhus polyacanthus (v25.04); male or unsexed record. These figures are not interchangeable: the first is the profile's editorial reference, whereas the second is a published maximum under a specific measurement convention; differences among sources can reflect sex, population, life stage and measuring method.
- Sex ratio
- Pair
- Visual sexing is virtually impossible outside of the breeding season when the female may appear slightly rounder. They are generally peaceful towards their own kind and can be kept in small groups if the tank is large enough. A group of three to five individuals increases the chances of a pair forming naturally.
- Feeding frequency
- Twice daily
- Due to their slow metabolism and inactive lifestyle, they do not need to be fed every day. Feeding them a suitably sized live prey item every two to three days is generally sufficient to keep them healthy. Overfeeding can lead to digestive issues and foul the pristine water conditions they require.
- Bioload
- Low to Medium
- The Amazon Leaffish produces a low bioload as it is small, inactive, and feeds infrequently. However, they demand exceptionally pristine water quality with zero ammonia or nitrites to survive. Strong biological filtration is necessary, but the physical flow must remain extremely low to accommodate their needs.
- Flow
- Stagnant
- They require almost completely stagnant water to mimic the quiet, leaf-littered pools of the Amazon basin. Even moderate currents will exhaust them and disrupt their delicate camouflage behavior. Gentle air-driven sponge filters are the ideal filtration method for this sensitive species.
- Jump risk
- No
- Reproduction
- Substrate spawner
- Breeding the Amazon Leaffish is a rare and highly prized accomplishment in the aquarium hobby. They are substrate spawners, typically laying their eggs on the underside of broad plant leaves. The male will fiercely guard the eggs and fan them with his fins until they hatch.
- Compatibility & tankmates
- Highly aggressive
- They are highly specialized ambush predators that will swallow any fish that fits into their surprisingly large, protrusible mouths. They must be kept in a species-only setup or with peaceful, heavily armored bottom dwellers like small Plecos. They should never be kept with aggressive fish that will outcompete them or stress them out.
- Tank level
- Middle
- They utilize all levels of the aquarium, orienting themselves vertically or at odd angles to perfectly mimic a dead, drifting leaf. They require dense vegetation, floating plants, and abundant leaf litter on the substrate to feel secure. Without these elements, their camouflage fails, and they will suffer from extreme stress.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 4.2 ± 0.73 se
- Phylogenetic uniqueness (PD50)
- 1.0312
- Bayesian Length-Weight
- a = 0.02042, b = 3.02
- VulnerabilityLow vulnerability (10 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
Related species
Recommendations grouped by close relatives, companion choices, and similar care.
