The oscar fish’s intelligent personality and attractive, marbled-orange coloring makes it an appealing aquarium fish. However, because of the oscar fish’s aggressive temperament, the fish is difficult to house in a community tank and unsuitable for beginners.
TABLE OF CONTENTS
Oscar Fish Facts & Overview
|Scientific name:||Astronotus ocellatus|
|Common names||Oscar fish, oscar cichlid, tiger oscar, velvet cichlid, marble cichlid|
|Distribution:||South America (Argentina, Brazil, Colombia, Paraguay, Peru, Uruguay, and Venezuela)|
|Life expectancy:||15–20 years|
|Color:||Orange and black/brown marbled colors|
|Minimum tank size:||55 gallons|
The oscar fish is found in parts of South America, including Argentina, Brazil, Colombia, Paraguay, Peru, Uruguay, and Venezuela. The fish swim throughout the freshwater Amazon and Orinoco Rivers and tributaries, enjoying the warm water temperatures and moderate-to-fast currents of these biodiverse environments.
Varieties of oscar fish have been bred in and introduced to other parts of the world, including Africa, Southern Asia, and North America. Oscar fish are also found in parts of French Guiana and Suriname.
Wild populations of oscar fish are common, and the fish are classed as non-extinct.
Adult Size & Lifespan
Full-grown oscar fish reach up to 12 inches in length. In the wild, oscar fish grow even longer, reaching lengths of up to 14 inches.
Oscar fish are monomorphic, which means there are no obvious differences between males and females in size or physical appearance.
In captivity, oscar fish live between eight and 15 years. In the wild, the fish live up to 20 years. Males and females have the same average lifespans.
Oscar fish are easy to find for sale in pet stores and online. The typical cost of an oscar fish is $12–$15 per fish.
These fish prefer to be housed in at least a pair. The upfront cost of two oscar fish is around $30.
- You can buy oscar fish (called “tiger oscar”) and albino oscar fish at liveaquaria.
- Aquaticarts is another reputable online store that sells standard and albino variations of oscar fish
Appearance & Behavior
Oscar fish are known as “tiger oscars” and “marble cichlids” because of their black/brown and orange markings.
The oscar fish species is considered one of the most intelligent aquarium species, but oscar fish have an aggressive, territorial side that makes the fish challenging to manage.
Colors, Patterns, Fins, and Sex Differences
Oscar fish have brown/black bodies with red or orange marbling. Some oscar fish variations have green or olive bodies. There are albino variations of oscar fish, which have white bodies with red patterning.
With large, oval-shaped bodies, oscar fish are a stocky aquarium fish species. The fish have large heads, large mouths, and large eyes. They have fan-shaped fins that extend the length of the fish’s body.
Male and female oscar fish are identical in shape and color.
When oscar fish are born, the fish’s colors are dull, and their dark markings are deep black. The colors of the fish become brighter and the black markings turn gray as the fish grow. A stressed or sick oscar fish will look duller than usual.
The most common type of oscar fish is the tiger oscar fish, but there are other subspecies of oscar fish that have their own unique appearances.
Red oscars have fiery-red coloring, while albino oscars are white and red.
Crossbred versions of the oscar fish include:
- blue oscars – typical oscar fish but with blue patterning
- black oscars – black fish with white bands running around their bodies
- white oscars – pale, pink fish
- green oscars – typical oscars with green and yellow coloring
Oscar fish are intelligent fish that swim with purpose around the tank. The fish recognize their owners and can be hand-fed, giving them the nickname “river dogs.” The oscar fish’s intelligence is an appealing quality for aquarists.
However, oscar fish are territorial and have aggressive tendencies. You should carefully choose which fish to house with oscar fish in a community aquarium to prevent fighting and stress amongst the fish.
If oscar fish feel that their territory is being invaded, the oscar fish will attack their tank mates, push other fish around, and chase the other fish. Oscar fish fight with fish of their own species, especially during breeding season.
Oscar fish are quick swimmers and prefer to frequent the middle section of the tank. They require plenty of open space. Oscar fish occasionally swim to the bottom of the tank to search for food in the substrate.
Although the oscar fish is a social species, it enjoys the privacy of caves and plants to hide in.
In an aquarium setting, oscar fish are active during the day and rest during the night. The fish prefer frequent small meals throughout the day.
Oscar Fish Care & Tank Requirements
Oscar fish have moderate care needs. Replicating the oscar fish’s freshwater tropical habitat and varied omnivorous diet is easy. However, because of the oscar fish’s aggressive tendencies, the fish requires extra care when housing with other fish species.
A large tank, consistent water parameters, and a strong water flow are the three most important tank requirements for oscar fish. You should feed oscar fish a healthy, varied diet of live foods, pellet foods, and plant matter.
Habitat and Tank Requirements
In the wild, oscar fish are found in the freshwater Amazon and Orinoco Rivers and tributaries. The oscar fish’s natural habitat is one of the most biodiverse environments on the planet, and you should aim to replicate this habitat in the aquarium, with warm, tropical waters and varied plant species.
To recreate the oscar fish’s natural habitat, fill a large, freshwater tank and introduce a soft, sandy substrate with debris, vegetation, and rocks scattered on top.
Oscar fish enjoy digging in the substrate and rearranging the tank, so plants should be hardy and firmly rooted, and tank decorations should be firmly fixed in place.
The desired tank conditions for oscar fish are listed below:
|Water type:||Medium-hard, freshwater|
|Tank size:||Minimum 25 gallons|
|Substrate:||Sand, rocks, and vegetation|
|Tank setup:||Plants, caves, and decorations|
|Water hardness:||5–20 dkH|
|Filter:||Yes, to create a strong current and clean the water|
|Bubbler:||Not essential, but can be used to help with oxidation of the water|
|Lighting:||Yes, to establish day times and night times for the fish|
Oscar fish can’t survive in temperatures below 55ºF, so make sure water temperature is consistent.
pH consistency is also important — oscar fish need a neutral pH, and aren’t used to acidic or alkaline waters.
Aside from water parameters, providing enough space for oscar fish to swim in and claim their own territories will benefit the fish’s long-term happiness and health.
There are several diseases that commonly affect oscar fish: hole in the head, Ich, and fin rot.
Hole in the Head
Hole in the head is a common freshwater disease caused by a parasite called hexamita. The disease is so-called because it leads to head lesions. It can also cause lesions on the fish’s torso, a loss of appetite, and color fading.
Prevent hole in the head by maintaining consistent water parameters. Reverse the disease by improving water quality and making sure the fish gets plenty of vitamin and mineral supplementation.
Ich is caused by a protozoan parasite called Ichthyophthirius multifiliis. This disease is commonly brought into an aquarium when new plants, live foods, and new fish are introduced. Symptoms of Ich include reddening of the fins, white spots on the gills and fins, and flashing (when fish rub their bodies against rough objects).
Treat Ich by adding one tablespoon of salt for every two gallons of water and increasing the temperature of the tank by a couple of degrees to speed up the lifecycle of the parasite.
Caused by a bacterial infection, fin rot occurs when oscar fish are stressed by poor water quality, overcrowding, or low oxygen levels. Fin rot is characterized by tattered or blackened fins with a milky appearance, lethargy, and loss of appetite.
Prevent fin rot by eliminating environmental stressors. Treat oscar fish with fin rot with antibiotics prescribed by your veterinarian.
Due to their aggressive, territorial personalities, oscar fish shouldn’t be housed with the majority of fish species.
Although oscar fish are used to being surrounded by other fish species in the wild, tensions can rise in a tank with limited space, causing fights, bullying, and fin-nipping. Housing these fish alone is best.
However, if you wish to establish a community tank, choose large, passive fish that won’t get in the way of oscar fish.
Great tank mates for oscar fish include:
- Firemouth cichlids
- Silver dollars
- Jaguar cichlids
- Green terrors
- Sailfin plecos
- Convict cichlids
- Severum cichlids
If you plan to house oscar fish together, make sure there’s enough room in the tank. Use a 55-gallon tank for one oscar fish, and add an extra 30 gallons for each additional fish.
Don’t add small fish or invertebrates, like shrimp and crabs, to the tank because oscar fish eat any fish that are smaller than their own size.
Diet and Feeding
In the wild, oscar fish eat a varied diet of larvae, small fish, and plant matter. As omnivorous, opportunistic fish, oscar fish eat anything they can find, and you should replicate this varied diet in captivity.
Feed oscar fish a combination of store-bought pellets or flakes, live/frozen food like daphnia and brine shrimp, and plant-based foods like algae wafers or green vegetables. Oscar fish have natural hunting instincts and enjoy catching and eating live food.
Split feeding into two or three sessions per day. In each session, only feed the oscar fish as much food as they can eat within two minutes.
Breeding oscar fish in captivity is difficult and often requires a lot of fish. Oscar fish are picky about their mates, and putting a male and female in the same tank in the right conditions doesn’t guarantee breeding success.
However, if you’re adamant about breeding oscar fish, here’s what you should do:
- Select a mature male and a mature female oscar fish (the fish typically mature after reaching one or two years old).
- Place the male and female in a separate breeding tank decorated similarly to the home tank. Lower the temperature of the water by a couple of degrees to mimic the rainy season of their natural habitat, which encourages breeding in the wild.
- Change the water every couple of days and sprinkle water on the surface to aerate the tank. Feed the fish a varied diet of live and frozen foods.
- If the pair are interested in one another, both fish will flare their gills and waggle or vibrate their tails. If the pair show no interest in one another or begin to fight, separate the fish and try with another pair, or try a new female with the same male.
- After successful breeding, the female will lay up to 3,000 eggs on a clean rock surface.
- The parents will guard the eggs for up to three days until the eggs hatch.
- Remove the male and female after the eggs have hatched to prevent the parents from eating the babies.
- Raise the fry in the tank with an added sponge filter and feed the fry specialized food for young fish, four times per day.
Should You Get an Oscar Fish for Your Aquarium?
If you’re planning to set up a new tank, preferably dedicated to a single fish species, oscar fish are a good choice to consider.
However, if you’re a beginner aquarist, or your tank already houses fish that oscar fish could bully or eat, oscar fish aren’t suitable for you. Oscar fish aren’t high maintenance, but the fish are known to fight and show signs of aggressiveness.
In the right environment, oscar fish are beautiful, colorful fish that exhibit intelligent, unique social behaviors.