After 12 hours it was noted that the skeleton was only supported by hyaline cartilage. Within just 6 hours after hatching, skeletal striated muscular tissue was observed along with the digestive tract containing visceral or smooth muscle tissue. These newly-hatched oscars had non-pigmented eyes, a closed mouth and anus, and a large liver. Hatching of the eggs occurred 46-58 hours after initial collection, with larve measuring about 3.25mm in length and about 1.55mm in height. Fifteen hours after the initial collection, the forebrain, cerebellum, notochord, and eyes of the embryo were formed, along with 2 pairs of adhesive glands in the upper sections of the head. The eggs from the initial collection were in the gastrula stage, the forming of a top (epiblast) and a bottom (hypoblast) layer due to migration movement. A selection of oscars in secondary maturation, with rounded abdomens and visible urogenital organs, were induced with two different hormones for artificial reproduction: extract of carp pituitary and synthetic human chorionic gonadotropin. (2015) described the early development histology of the oscar by induced reproduction. Range length 30 to 40 cm 11.81 to 15.75 inĪlthough little is known about the development of Astronotus ocellatus, there have been two studies focusing on embryonic and larvae development for this species.Variations of Astronotus ocellatus include longer fins, black coloration, red coloration in the markings, and a white body with orange markings throughout. The author found that the fish displayed different color patterns based on how the oscars responded. Color pattern changes occur based on different behaviors and developmental stages, as reported by Beeching (1992), using dummy fish. The eyes are dark with a thin red outline and the lips are thick and fleshy.Ĭharacteristic of cichlids, oscars have a single nostril on each side of the snout, and have pharyngeal jaws. The fan-like fins are dark with light edging. They have characteristic ocelli at the base of the dorsal fin, which are black with an orange and red outline along with a lighter-colored vertical mark at the base of the anal fin. Although there are many varieties of this species, the wild-types are a dark green/brown color with varied markings of orange, red, and yellow on the sides. The average length of an oscar is between 30-40cm (35cm average), and average mass is 1.58kg by adulthood. Because they are mostly bottom-dwellers and feeders, they live in areas that have muddy or sandy substrates. The water they inhabit has a fairly neutral pH (6-8), with moderate hardness, and tropical temperatures of 22-25 degrees Celsius. Oscar habitats are found within shallow, calm, freshwater rivers or basins. Oscars have been used in Florida as game fish and are common aquarium fish. There are many varieties of this species that have been bred and introduced to southern Asia, North and Central America, and Africa. Oscars are also found in parts of Surinam and French Guiana. These river basins are a complex of waterways that include Argentina, Brazil, Colombia, Paraguay, Peru, Uruguay, and Venezuela. Oscars are native to South America, throughout the Amazon and Orinoco Rivers and tributaries. Oscars, Astronotus ocellatus, are freshwater fish found in areas with warm water temperatures.

Oscar fish size