The Amazon leaffish (''Monocirrhus polyacanthus''), or South American leaffish, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of fish belonging to the family

Polycentridae Leaffishes are small fishes of the family Polycentridae. According to FishBase, it only includes the genera '' Monocirrhus'' and '' Polycentrus'' from fresh and brackish water in tropical South America. Although included in the Asian leaffish fam ...

. It is found in the

Amazon basin The Amazon basin is the part of South America drained by the Amazon River and its tributaries. The Amazon drainage basin covers an area of about , or about 35.5 percent of the South American continent. It is located in the countries of Bolivi ...

Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

and

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...

, where it inhabits edges of rivers and lakes, and streams. It is generally a low-density species that lives in slow-moving or essentially stagnant waters in areas with plant debris. Amazon leaffish are sometimes kept in aquariums, but they require acidic water, low light and live prey.

Appearance

The Amazon leaffish reaches a maximum

standard length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish m ...

of , and a total length of . As suggested by its common name, it closely resembles a dead leaf. The flattened body and filament at the tip of the lower jaw (resembling a stalk) further enhances its similarity to a leaf. It is gray-brown, but can change its color to some extent. There is no

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...

and its large mouth can be protracted to as much as 60% of the head length.

Behavior

The Amazon leaffish is highly predatory, feeding on small invertebrates (aquatic insects like

mayfly Mayflies (also known as shadflies or fishflies in Canada and the upper Midwestern United States, as Canadian soldiers in the American Great Lakes region, and as up-winged flies in the United Kingdom) are aquatic insects belonging to the ord ...

nymphs A nymph ( grc, νύμφη, nýmphē, el, script=Latn, nímfi, label=Modern Greek; , ) in ancient Greek folklore is a minor female nature deity. Different from Greek goddesses, nymphs are generally regarded as personifications of nature, are typ ...

and crustaceans like shrimp) and fish (especially Characids and Lebiasinids). Small

Amazon Amazon most often refers to: * Amazons, a tribe of female warriors in Greek mythology * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon River, in South America * Amazon (company), an American multinational technology c ...

leaffish mostly feed on

invertebrates Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

, while larger individuals mainly feed on

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

. The prey fish are swallowed whole and they are often quite large compared to the size of the leaffish. The prey fish length is typically about of the length of the leaffish, but can be up to around the length. The

camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the ...

allows the Amazon leaffish to both escape the attention of larger predators and ambush smaller prey. It swims very slowly in a head-down position, resembling a dead leaf floating in the current, to approach its prey. When near, it protracts its mouth to form a tube. The prey is rapidly sucked in, usually head-first. Prey in its stomach is often folded, allowing the leaffish to fit relatively large items. Before breeding, the pair swims next to each other. The female lays up to 300 eggs on the underside of a rock or plant leaf, which are then fertilized by the male. The male takes care of the eggs, which hatch after 3–4 days. They are predators from the start of their lives, first feeding on tiny animals like

brine shrimp ''Artemia'' is a genus of aquatic crustaceans also known as brine shrimp. It is the only genus in the family Artemiidae. The first historical record of the existence of ''Artemia'' dates back to the first half of the 10th century AD from Urmia La ...

and

water flea The Diplostraca or Cladocera, commonly known as water fleas, are a superorder of small crustaceans that feed on microscopic chunks of organic matter (excluding some predatory forms). Over 1000 species have been recognised so far, with many more ...

References

{{Taxonbar, from=Q882185 Polycentridae Fish described in 1840 Fish of Bolivia Freshwater fish of Brazil Freshwater fish of Colombia Freshwater fish of Peru Fish of Venezuela