''Colomesus asellus'', the Amazon puffer, asellus puffer, South American freshwater puffer or Peruvian puffer 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 ...

pufferfish Tetraodontidae is a family of primarily marine and estuarine fish of the order Tetraodontiformes. The family includes many familiar species variously called pufferfish, puffers, balloonfish, blowfish, blowies, bubblefish, globefish, swellfis ...

confined to the

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 ...

Essequibo Essequibo is the largest traditional region of Guyana but not an administrative region of Guyana today. It may also refer to: * Essequibo River, the largest river in Guyana * Essequibo (colony), a former Dutch colony in what is now Guyana; * Esseq ...

and

Orinoco The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers , with 76.3 percent of it in Venezuela and the remainder in Colombia. It is the fourth largest river in the wor ...

basins in tropical South America. It is a popular

aquarium An aquarium (plural: ''aquariums'' or ''aquaria'') is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aq ...

species. It has typically been recognized as the only true freshwater pufferfish of South America, but a study in 2013 recommended that the population in the

Tocantins River The Tocantins River ( pt, Rio Tocantins, link=no , , Parkatêjê dialect, Parkatêjê: ''Pyti'' ɨˈti is a river in Brazil, the central fluvial artery of the country. In the Tupi language, its name means "toucan's beak" (''Tukã'' for "toucan ...

basin (quite similar to ''C. asellus'' in appearance, but differs in genetics) should be considered as a separate species, ''C. tocantinensis''. This is followed by

Catalog of Fishes Catalog of Fishes is a comprehensive on-line database and reference work on the scientific names of fish species and genera. It is global in its scope and is hosted by the California Academy of Sciences. It has been compiled and is continuously up ...

, but not

FishBase FishBase is a global species database of fish species (specifically finfish). It is the largest and most extensively accessed online database on adult finfish on the web.

Description

The coloration of this fish is green above, white below, and patterned with black transverse bands across the dorsal surface. Compared with ''

Colomesus psittacus ''Colomesus psittacus'', the Banded puffer, parrot puffer or South American estuarine puffer, is a species of pufferfish found all along the Western Atlantic coastline of South America from the Gulf of Paria down to the mouth of the Amazon River ...

'', the black bands on the back are much thicker, and it also has a distinctive black band that rings the base of the

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

. This species grows to a length of SL. It is known to contain the toxin

saxitoxin Saxitoxin (STX) is a potent neurotoxin and the best-known paralytic shellfish toxin (PST). Ingestion of saxitoxin by humans, usually by consumption of shellfish contaminated by toxic algal blooms, is responsible for the illness known as paralytic ...

, and

gonyautoxin Gonyautoxins (GTX) are a few similar toxic molecules that are naturally produced by algae. They are part of the group of saxitoxins, a large group of neurotoxins along with a molecule that is also referred to as saxitoxin (STX), neosaxitoxin (NSTX ...

such as the GTX 2 and GTX 3.

Ecology

''Colomesus asellus'' is normally only found in freshwater environments although it will tolerate slightly

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

water. Wild ''Colomesus asellus'' are reported to consume benthic crustaceans, fish, planktonic invertebrates, and plants. Aquarium specimens consume various invertebrates including midge larvae and

Mysida Mysida is an order (biology), order of small, shrimp-like crustaceans in the malacostracan superorder Peracarida. Their common name opossum shrimps stems from the presence of a Brood pouch (Peracarida), brood pouch or "marsupium" in females. The ...

. Like other pufferfish, they have the ability to inflate themselves when threatened, making themselves much larger and therefore more difficult for predators to handle or swallow. ''Colomesus asellus'' is unusual among freshwater pufferfish for being migratory and non-territorial. ''Colomesus asellus'' is known to breed during the wet season, spawning in rivers, with the numerous small eggs being scattered on the substrate and the

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

e drifting downstream. ''Colomesus asellus'' is nearly impossible to breed in the aquarium because their eggs are very small and they go through a planktonic phase before growing into "real'' fish.

In the aquarium

''Colomesus asellus'' is fairly widely kept as an

fish. An aquarium tank with volume of at least 109 liters is required ( approx. 29 US gallons). Compared to other freshwater pufferfish, ''Colomesus asellus'' is unusual in being tolerant of

conspecific Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species. Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organ ...

s and tends to be nervous when kept singly. It is known to be a fin-nipper and could attack slow moving species such as

angelfish Angelfish may refer to: *Several groups of fish: **Freshwater angelfish, tropical cichlids of the genus ''Pterophyllum'' **Marine angelfish of the family Pomacanthidae **Atlantic pomfret (''Brama brama''), sold by fishmongers as "angelfish" in Sou ...

guppies The guppy (), also known as millionfish and rainbow fish, is one of the world's most widely distributed tropical fish and one of the most popular List of freshwater aquarium fish species, freshwater aquarium fish species. It is a member of the ...

, and ''

Corydoras ''Corydoras'' is a genus of freshwater catfish in the family Callichthyidae and subfamily Corydoradinae. The species usually have more restricted areas of endemism than other callichthyids, but the area of distribution of the entire genus almost ...

''. ''Colomesus asellus has some of the fastest growing teeth of the freshwater puffers so, feeding crunchy foods and possibly having to do dentistry are two important factors.''

References

{{Taxonbar, from=Q13583745 Tetraodontidae Fish described in 1849