Oscar fish are members of the family Cichlidae and one of the most popular large aquarium fish. They are native to several countries along the Amazon River basin in South America. As predators, they feed on smaller fish and invertebrates. Oscars are hardy, long-lived, and not difficult to care for. Many aquarists choose them as their first big fish.
Oscar fish recognize their owners and some allow themselves to be stroked underwater. They eat from your fingers and watch you while you work nearby. A trained oscar is as close to a dog as any fish gets.
- Common Names: Oscar Fish; Oscar Cichlid; Velvet Cichlid; Marble Cichlid; Tiger Oscar; Albino Oscar Fish
- Scientific Name: Astronotus ocellatus
- Origin: Amazon River basin, South America
- Length: 15 inches
- Aquarium Size: 65+ gallons
- Temperament: Semi-aggressive
- Ease of Care: Easy
Oscar Fish Appearance
Oscar cichlids are variable in appearance. The same fish will shift colors to match sudden changes in lighting or background darkness. Oscars use their color changes as camouflage and to signal to other oscar fish their mood.
All oscars have a black dot ringed with red; the mark is called an ocellus or eye mimic (described in the latin name A. ocellatus). The ocellus is thought to confuse piranhas and Amazonian scale eating fish that like to attack their prey from behind. Since the oscar appears to be looking in both directions the attacker gets confused.
The true eyes of oscars stick out. Beginners mistake this for popeye and other bacterial fish diseases. Oscars can catch popeye but a healthy fish will still have protruding eyes. They are chunky cichlids, with short fins and a large mouth. As ambush predators, oscars are built for short bursts of speed to surprise smaller fish.
Red Oscar Cichlid
Captive breeding results have created several types of oscar fish. The red oscar is the most popular breed. Wild oscars have a few red scales; red oscars are covered in them. Unlike a tiger oscar, there are no stripes.
Tiger Oscar Fish
Tiger oscars are the next most popular oscar breed. They have bands of bright orange to red scales, with large black patches on their backs, head, and sides.
Albino Oscar Fish
Albino oscars come in both tiger and red morphs. As true albinos their eyes are pink, with creamy white scales replacing the black patches.
Lemon Oscar Cichlid
Lemon oscar fish resemble an albino oscar at first except they have dark eyes and may show black in their fins. As a newer variety, expect to pay more for a lemon oscar.
Black Oscar Fish
Black oscars are closest to wild oscar colors. They have muddy brown to deep black tones with a few red scales along their sides and tail. Black oscar fish are the least common since aquarists prefer fish with bright colors. Many black oscars are wild caught fish and are of interest to fish breeders looking for new genetics.
How to Tell if an Oscar is Male or Female?
Sexing oscar fish is difficult even for expert breeders. These fish don’t show visual differences. Males and females are the same size and similar in color pattern. Males don’t have dorsal fin extensions or nuchal humps like other cichlids. Oscars tell each others’ sex through hormonal release and subtle behavior cues.
One visual clue that mature oscars offer is to examine their sexual organs. The organ is a white protrusion .5 to 1 cm in front of the anus. In a male oscar the organ has a pointed shape. Female oscars have a rounded tube for egg laying. The organ is most visible when the fish are ready to spawn or have eaten a large meal.
Oscar Fish Tank Size
Oscar fish are heavy bodied fish that create a lot of waste. A spacious aquarium ensures that ammonia levels don’t become dangerous. As cichlids, oscars are also territorial and aggressive. Oscar fish tank mates need space to avoid them.
A 65-75 gallon aquarium is the minimum for a full grown oscar fish or a mated pair. A 40 breeder or 55 gallon aquarium is suitable for the first year of life. Oscars grow about an inch per month and slow down when they reach sexual maturity at 6 inches. An 8 to 10 inch oscar will need a larger tank since 55 gallon tanks aren’t wide enough.
Oscar Fish Tank Aquascaping
Decorations for oscar aquariums should be chosen with care. Large cichlids are avid diggers. They move piles of gravel around to look for food and prepare sites for spawning. Even a lone oscar with no mate will dig.
Digging behavior will destabilize rocks and driftwood that isn’t secured. A rock collapse can break a heater or injure your oscar fish. Rocks need to be buried halfway without touching the bare aquarium glass to prevent cracks or breaking. Driftwood is soft and won’t break tank glass. The base of each piece should be placed deep in the substrate.
Live plants that have roots in the gravel will be uprooted and killed. Stick to plants that attach to hard surfaces (epiphytes). Good aquarium epiphytic plants include:
Floating plants are also good additions. Floating plants grow fast, require little maintenance, and create shade that prevents algae growth. The natural oscar fish habitat is murky water full of driftwood and plant life. Lowering incoming light with floating plants makes oscars more comfortable.
Water Conditions for Oscar Fish Care
The Amazon River basin creates year-round tropical conditions and oscar fish require the same in terms of water temperature. 75-80℉ is their preferred range, with a pH of 6.0-7.0.
Oscar cichlids have been aquarium raised for many generations and don’t require soft, acidic conditions for a long lifespan. Alkaline water up to pH 7.6 is suitable. If you want to breed oscars then you will need to lower the pH. Adding driftwood and Indian almond leaves slow release plant tannins that darken the water and add natural acids.
Nitrogenous waste products should be monitored biweekly through water testing. Low levels of ammonia or nitrite aren’t dangerous as oscars are not as sensitive as other fish. They still cause them stress so be sure to do a water change ASAP. A well maintained power or canister filter keeps nitrogenous waste in check through biological filtration.
Oscar Fish and Hole in the Head Disease
Oscar fish are prone to developing hole in the head (HITH) disease. The symptoms are holes and pits that form around the head and lateral line. Hence the alternative name: head and lateral line erosion.
HITH disease has mysterious origins. The two most likely causes are a combination of parasitic infection and a nutritional imbalance. Hexamita are flagellate parasites that infect the internal organs of oscar fish. As the disease worsens, holes appear in the skin and scales. The holes open routes for bacteria and fungi to infect the oscar, weakening it further.
HITH disease is also found in saltwater tang fish and is known to be caused by dietary deficiencies. An oscar that eats the same poor quality pellet diet for years will show pits in their face and lateral line.
Poor water conditions, including constant high ammonia levels, increase the chance of an oscar cichlid developing HITH. To reverse it, start treatment using Metronidazole based medications like Seachem MetroPlex.
Assuming the disease is not caused by Hexamita parasites, add fresh and frozen foods to their diet. That, coupled with excellent water quality, will halt the spread of HITH. The pits may leave permanent scars. Healing is based on how fast you treat the disorder.
What to Feed an Oscar Fish
Oscar fish are omnivores that eat smaller animals with a small amount of plant material. Fish are their preferred prey, followed by shrimp, worms, insects, frogs, and other aquatic life.
Wild oscars are ambush hunters that strike from the shadows. They also play dead by lying on their sides. When smaller fish come to investigate the oscar opens its mouth wide, sucking them inside.
In the rainy season oscars will eat fruit and seeds washed into the river. Animal protein remains is their primary source of food. Tank raised oscars are used to eating pellets. Cichlid pellets with whole animal ingredients and color enhancers are the best food for oscar fish.
Mix in fresh treats like insects, earthworms, and seafood to prevent HITH disease. Don’t feed oscar fish chicken or beef heart. These items are too high in fat and harder to digest. Fresh food will cause cloudy aquarium water if fed too often.
Young oscars grow fast and need to eat three times per day. A full grown oscar fish should eat once or twice per day.
Oscar Tank Mates
Oscars are not as aggressive as other large cichlids. Any fish they cannot eat is a suitable tank mate. You have to be careful when adding oscar fish to mixed cichlid communities. They are prone to being bullied by flowerhorns, red devils, and other aggressive species. Keep oscars with semi-aggressive cichlid species.
Large, peaceful fish are good additions. Predators like arowanas will eat the same food as your oscar yet won’t bully them. Large schooling fish like silver dollars add activity and color contrast as well.
- Jack Dempsey
- Electric Blue Acara
- Green Terrors
- Banded Leporinus
- Arowanas
- Severum Cichlid
- Pacu
- Silver Dollars
- Large Barbs
- Plecostomus
- Freshwater Stingrays
Oscar Fish Breeding
Breeding oscar fish is more challenging than keeping them healthy. Soft, acidic water conditions increase your chances. Offering plenty of fresh food does as well. The hardest part is finding a compatible pair because the fish offer few clues to their sex.
The best way to get a mated pair is to raise 4 to 6 young oscars together. They reach sexual maturity at 5 to 6 inches.
At least one pair will form and start to bully the other oscars, who need to be rehomed. Oscars are aggressive parents that provide excellent care for their eggs and fry. Any tank mates will be stressed to death from constant attacks so keep breeding oscars alone.
Perform frequent water changes with soft water, feed more fresh foods, and raise the temperature to 82-86℉. Oscar fish will lay up to 3,000 eggs at a time.
The female cares for the eggs, fanning them to provide a current of oxygen-rich water. Meanwhile the male patrols the tank looking for intruders. He will try to attack you, your fingers, or aquarium cleaning tools if they get too close to the eggs.
Oscar fry hatch after 2 to 3 days of development. The fry won’t eat at first; they have a nutrient-rich yolk sack to sustain them. 2 to 3 days after hatching, offer them live brine shrimp nauplii until they are large enough for daphnia and crushed flake food.
Powdered egg yolk is a good alternative if you don’t have time to raise brine shrimp. It fouls water quality fast. Perform more water changes to keep ammonia undetectable as oscar fry are very sensitive to it.
FAQs
Oscar cichlids are omnivores that eat smaller fish, aquatic invertebrates, and fruit that fall into the Amazon river during the rainy season. Captive raised fish eat flakes when young and pellet formulas. Include fresh foods like chopped seafood, earthworms, and insects for extra nutrition to prevent hole in the head disease.
Oscars are not very aggressive. Any fish they can’t eat is a suitable tank mate. Other large cichlid tank mates should not be too aggressive or they may stress the oscar fish. Plecostomus, stingrays, large barbs, and arowanas are good tank mate choices.
The average oscar fish lifespan is 10 to 15 years. The oldest known oscar reached 20 years of age.
Keeping multiple oscar fish requires a large tank. 65 to 75 gallons is good for a single oscar or one mated pair. For each additional adult oscar, add 20 to 30 gallons of space. A group of 4 to 6 six-inch oscars require 55 gallons of space. Once a male and female pair off, the other fish will need new homes.
Hi I have albino Oscar I’m planning to put up a black background do you think by any chance it’s gonna affect my Oscar..!?