Monday,26 July 2021, 5 : 43 PM

Astronotus crassipinnis

Astronotus crassipinnis
Image Credit: wikipedia


Astronotus crassipinnis is a close relative to the famous Oscar fish Astronotus ocellatus.
The name crassipinnis is derived from the Latin words crassus and pinna which means "fat" and "fish" respectively.


Crassipinnis are member of Genus Astronotus which is placed in subfamily Astronotinae.
Crassipinnis was scientifically described by Heckel in 1840 and given the name Acara crassipinnis, but is now considered a member of the genus Astronotus.


Astronotus crassipinnis reaches a standard length of 9" , compared to 18" for Astronotus ocellatus
Both species are known to exhibit a variable bar pattern, but Crassipinnis is overall darker than Oscar and its anterior most light vertical bar is located more anterior than on an Oscar.
The area where one would find the first light bar on an Oscar is instead decorated with two more or less well-separated dark vertical bars on a Crassipinnis.
In addition to this, Crassipinnis does not have the two eye-spots along the base of its dorsal fin that adorns the western Amazonian Oscar.

Distribution & Habitat

Astronotus crassipinnis is found are Rio Paraguay, Villa Maria and Caisara, Rio Guaporé close to Matogrosso, Rio Negro, and Rio Branco.
The species inhabits the Bolivian parts of the Amazon and the Rio Madre de Dios drainage in Peru, plus the Rio Paraná basin in the Rio Paraguay drainage in Paraguay and Brazil.

Sexual Dimorphism

Astronotus crassipinnis is monomorphic. i.e male and females are alike, just like its close cousin Astronotus ocellatus.


Astronotus crassipinnis is carnivorous by nature and may be fed prepared fish food designed for large carnivorous fish, crayfish, worms, and insects ( such as flies or grasshoppers).
Feeding live foods may increase the rate of growth but also may cause endoparasites.
Poultry and/or mammalian flesh, including beef heart, should not be fed long term as these fatty foods will contribute to fatty liver disease.
Live feeder fish can be given, but fish such as goldfish and rosy red feeder minnows should not be fed.
These contain an enzyme (thiaminase) within their flesh which binds vitamin B1, leading to deficiency.

Keeping in Aquarium

Tank Size:

Compared to the popular Oscar, very little is known about Astronotus crassipinnisand the information that does exist is often vague or conflicting.
It is still rare within the hobby and seldom exported from South America, and the regions in which it lives are far from thoroughly explored.

However , it is important to have or be prepared to eventually get a large aquarium.
It is true that the largest scientifically measured Crassipinnis was 24 cm / 9.4 in, but this doesn't mean that it must be impossible for this species to grow any larger there might be even larger specimens lurking in South America unknown to science.

Since we still know so little about Astronotus crassipinnis it is best to play it safe and assume that it might one day become as large as an Oscar.
Also keep in mind that the comfortable life in a well-kept aquarium can make some species grow much larger than they would in the wild.


Since Astronotus crassipinnis is quite a messy eater and produces a lot of waste, powerful mechanical and biological filtration is typically necessary even in large and under-stocked aquariums.
Even with powerful filtration, it is important to keep an eye on the water quality.

Substrate & Decor:

As the Astronotus crassipinnis lives in South America the layout of aquarium should mimic that environment.
Mangrove roots or similar is a good idea since roots will provide your fish with dark and sheltered spots for resting.
Live plants floating on the surface will also be highly appreciated and make your fish feel more at home.
Planted plants can also be used, but your Crassipinnis may uproot them so ideally go for robust species.

Water parameters:

Astronotus crassipinnis needs soft water and acidic water with a pH of 6.5-6.9.
The species live in tropical South American rivers and the recommended water temperature in the aquarium is 21-28C / 70-83F.
If you decide to keep the water in the upper part of the range, don't forget that warm water holds less oxygen than cooler water.
If your filtration system isn't enough to keep the oxygen level up you can get one or several air stone.


Astronotus crassipinnis has been observed, in times of danger, to store brood in its mouth, possibly for protection, in a manner reminiscent of mouth brooding Geophaginae cichlids.
This behavior, however, has not yet been observed in A. ocellatus.

Species Snapshot

Species Card

Particulars Details
Scientific Name Astronotus crassipinnis
Common Name
Genus Astronotus
Subfamily Astronotinae
Geographical Origin Near Rio Paraguay, Villa Maria and Caisara, Rio Guaporé close to Matogrosso, Rio Negro, and Rio Branco
Diet Carnivore
Gender Differences Mono morphic
Breeding Substrate Spawner
Temperament Aggressive
Con Specific Temperament Aggressive
Water hardness Soft, ph range: 6-7, dH range: 5-19
Difficulty Level in Aquariums

Morphometric Data

Particulars Details
Total Length(inches) 8.30
Standard Length(inches) 6.38

Measurements as % of Total Length

Particulars Details
Body Depth 44.70 %
Head length 32.70 %
Pre Dorsal length  %
Pre Pectoral length  %
Pre Anal length  %
Pre Pelvic length  %
Caudal Peduncle Depth 17.30 %
Caudal Peduncle Length 7.30 %
Fork length  %
Length of Last Dorsal Fin Spine 11.90 %
Pectoral Fin Length 33.70 %
Pelvic Fin Length 29.60 %

Measurements as % of Head Length

Particulars Details
Head Width 19.10 %
Snout length 6.90 %
Eye diameter 8.90 %
Pre Orbital Length  %
Inter Orbital Width 13.20 %
Pre Orbital Depth  %

How to use the Web site presents articles on various interests to aquarists. Following general articles are provided.

Articles related to technical aspect of Fish keeping :

Articles related to Fish Groups :

Articles related to Fish Sub Families :

Articles related to Fish Genus :

Articles related to Fish Species :

and many more