Oscar | Astronotus ocellatus
Cichlids / South America / Oscar
Profile: Oscar, Velvet Cichlid
Astronotus ocellatus Synonyms: Acara ocellatus, Cychla rubroocellata, Hydrogonus ocellatus, Lobotes ocellatus
Physical description: The body is moderately compressed and oval shaped. The caudal fin is rounded, while the anal and dorsal fins are often pointed. Several different color variations are available, although the common form is fairly uniform. Juvenile fish are gray to black in color with a pink marbled-ring pattern on the body. Adult fish have a olive back with black and orange lower parts. An obvious tail-spot can be seen near the caudal peduncle.
Size/Length: To 14" (35 cm)
Similar species: Astronotus crasspinnis of Peru.
Habitat: South America; wide distribution from the Orinoco River Basin to the Rio Paraguay.
S: bottom, middle
Aquarium: A tank measuring 30" (76 cm) with a capacity of 20-25 (75-98 L) gallons is sufficient for small individuals under 5" (13 cm) in length. Adult fish require a tank measuring at least 72" (183 cm) with a capacity of 100 gallons (378 L). The tank should have a deep substrate with some large rocks. Plants must be potted and robust with their stems and root protected with rocks. Arrange heaters so that they will not become unattached from the tank glass. The tank must have powerful filtration.
Water chemistry: pH 6-8 (6.9), 4-20 dH (10), 72-79°F (22-26°C)
Social behavior: A peaceful cichlid despite its large size. Many make the mistake of placing the Oscar in tanks with fish that are too aggressive. The Oscar should be combined in a large community aquarium with other similarly-sized companions. Pairs become aggressive while spawning and participating in brood care. Oscars will burrow in the substrate.
Suggested companions: Catfish (Loricarids, Pimelodids, Doradids), characins (Silver Dollars, Leporinus, Anostomus ), cichlids (Severum, some Cichlasomines), Arawana, Knifefish.
FOOD: Live; fish, earthworms, Tubifex, large insects, aquatic insects, large crustaceans; chopped meat; pellets; tablets; spinach. The Oscar is a greedy and messy eater.
SEX: Sexes are only distinguishable at spawning times when the female has a more obvious, rounded genital papilla.
Breeding techniques: Breeding usually only takes place in a very large tank (i.e. 150 gallon-568 L). The water must be kept clean and at a warm temperature of 79-86°F (26-30°C). Once a pair bonds, it may remain together for over ten years, spawning on a regular basis. As many as 2000 opaque, white eggs are laid on previously cleaned rocks. The eggs look like they have fungus, although the clear up after 24 hours. If the eggs do not clear up in this time, they probably do have fungus. Both parents participate in brood care. The eggs hatch after three to four days, and the larvae are moved to shallow pits. There the young remain until they are free-swimming six to seven days later. Sometimes the young may affix themselves to the flanks of the parents. Start feeding with roftiers, Artemia nauplii, and Cyclops nauplii. The young grow quickly and are large enough for sale at 1" (2.5 cm).
Breeding potential: 7. Breeding is moderately difficult partly because of the large tank required. The eggs are susceptible to fungus. Once a pair spawns successfully, regular spawnings can be expected.
Remarks: Oscars are available in several colors do to selective breeding. Common pattern morphs available are the Tiger, Red, Albino, Jewel, and Veil-tail varieties. The Oscar has a wide distribution which has lead to the debate over different populations. Some of these populations are thought to be different species of Oscar, other than A. ocellatus . The Oscar creates large amounts of waste in the tank, thus it is important to perform frequent water changes. If the water is not maintained, the Oscars may become susceptible to hole-in-the-head disease. Occasionally wild-caught fish are imported, although these lack the colors of selectively-bred Oscars, and are more delicate. Oscars are well-known for their fondness of their keeper. After a few months, the Oscar can recognize its owner and without concern, take food right from the keeper's hand. A food fish in its native lands.
Difficulty of care: 7. Care is moderately difficult because this carnivore reaches a large size and requires a good-sized tank. Do not buy this fish with intentions of keeping it in your 10-, even 20-gallon, tank.