Oscars are a popular species of freshwater aquarium fish known for their large size and dog-like personalities. These fish can be a joy to keep in the home aquarium but it is essential that you provide them with the proper tank setup to ensure that they thrive. Because Oscars grow fairly large, they will not thrive in a small tank and they generally do not get along well with other cichlids. The key to ensuring that your Oscars live a full and healthy life is to create a tank environment that mimics their natural environment. Before you can do that, however, you must learn some basics about these beautiful fish.
Known by the scientific name Astronotus ocellatus
, Oscars belong to the cichlid family
of fishes which contains over 2,000 separate species. Other names for this species include velvet cichlid, tiger Oscar and marble cichlid. The natural habitat of these fish is South America where they can be found throughout the Amazon River basin in slow-moving waters, typically hiding amongst submerged branches and aquatic vegetation. Because this species does not tolerate cool water temperatures, its distribution is fairly limited – temperatures below 55°F can actually be lethal for Oscars.
Oscars have been known to grow up to 18 inches long, weighing more than 3 pounds at maturity. In captivity, this species generally grows to a maximum of 12 inches, but larger specimens have been reported. In the wild, Oscars often exhibit dark-colored bodies with yellow-ringed spots called ocelli located on the dorsal fin and caudal peduncle. It is thought that these spots serve to deter fin-nipping by fish like piranhas which share the Oscar’s natural habitat. Oscars also have the unique ability to change their coloration, particularly when they are feeling territorial or combative. Juveniles of the species exhibit different coloration from adults – they are typically striped with orange and white bands, having spots on their heads.
Tank Size and Requirements
Because Oscars typically grow about 10 inches long in captivity, the minimum tank size recommended for a single Oscar is about 55 gallons. Ideally, however, a 75-gallon tank is best for one adult Oscar and, if you plan to keep more than one, you will need a tank at least 100 gallons in capacity. In addition to supplying your Oscars with the right size tank, you also need to cultivate the right tank conditions. The ideal temperature range for this species is between 77° and 80°F and a pH level between 6 and 7.5. Decorations in the tank should be sparse or large enough that the fish cannot easily move them because Oscars have a habit of rearranging their tanks.
Recommended Tank Mates
Because Oscars are such a large species, you need to be careful about keeping them with other fish – none of your fish are likely to do well if they do not have adequate tank space. Before you go out and buy tank mates for your Oscar, you need to realize that it isn’t actually necessary for you to do so. Oscars can do quite well on their own and they are unlikely to get “lonely” if kept in a solitary tank. If you want to keep your Oscar with other fish, however, there are a few things you need to keep in mind as you look:
- Do not buy any fish that is small enough to fit into your Oscar’s mouth (nothing smaller than 5 inches is ideal)
- Look for fish that will not be overly timid – they must be able to compete for food in the tank
- Avoid fish that are very timid or shy – the Oscar may chase them around the tank, causing them stress
- Consider bottom-dwelling fish that will stay out of your Oscar’s way (Oscars prefer the top to mid-level areas)
It may seem like a lot of extra work to do the research necessary to find the ideal tank mate for your Oscar, but it is definitely worth it. The last thing you want to do is introduce a new fish into your tank only to have your Oscar bully it around (or worse, eat it). Given the requirements listed above, some of the best species for Oscar tank mates include catfish, Silver Dollar fish, Firemouth cichlids, Convict cichlids and blue acara. Avoid larger cichlids like Texas cichlid and terrors because these fish are likely to cause aggression problems in the tank.
Equipment and Lighting
While many cichlid species can be considered “messy,” the Oscar is particularly known for this trait. Due to their size, Oscars produce a significant amount of waste which can contribute to high levels of ammonia and nitrate in the tank if you are not careful. For this reason, it is essential that you equip your tank with a high-quality filtration system
and that you perform regular water changes to maintain high water quality. While mechanical filtration is important for removing solid wastes from the tank water, chemical filtration is essential for removing toxins like ammonia and nitrite. Many Oscar enthusiasts recommend canister filters for Oscar tanks because they are easy to use and they provide very efficient filtration -- you can also customize them by choosing your own filter media
depending on the needs of your tank.
In addition to filtration, heating is also very important in an Oscar tank. Because these fish come from a tropical habitat, they require warm water, generally within the 77° to 80°F range. To achieve this, you will need to equip your tank with a quality aquarium heater. Ideally, you should place a submersible heater near the return valve of your filter or use an in-line heater that can be connected to your canister filter so the water is heated as soon as it is returned to the tank. If you use a submersible or hang-on heater, be sure to purchase one that is shatterproof because Oscars can be destructive in the home aquarium. In terms of aquarium lighting
, Oscars do not have any specific requirements but, if you plan to keep live plants in the tank, you will need some kind of lighting. The natural environment of wild Oscars, however, tends to be dim and murky so your Oscars may also enjoy this type of environment.
Other Tips and Info
Oscars are a carnivorous species by nature so they should be fed commercial foods that are primarily meat-based. Live foods
such as insects, worms, crayfish, feeder fish and aquatic invertebrates are a good food source for this species though, in the wild, they feed primarily on small fish and insects. Some Oscars will also accept frozen foods as long as they have been thawed first. When feeding your Oscar feeder fish like goldfish, it is best to raise the feeder fish yourself so you can ensure that they are healthy – if you feed your Oscar feeder fish that have been exposed to disease, they could pass it on to your Oscar.
If you are looking for a fun and interesting fish to cultivate, Oscars are an excellent choice. Just be sure you provide your Oscars with a healthy tank environment and you will be rewarded by a happy and healthy fish.