How to Care for Oscar Fish: Keeping Oscar Fish Healthy

Do you have an Oscar fish and are wondering how to care for it? This guide will walk you through the process of keeping your Oscar fish healthy and happy.

Factors to Consider to Keep Oscar Fish Healthy

Astronotus ocellatus is a popular aquarium fish in the cichlid family.

Tank Size & Structure

A tank that is big enough for an Oscar fish should hold at least 55 gallons of water and should have a tight-fitting cover. The tank should also have live plants and a hiding place for the Oscar fish. They also require plenty of hiding places and plants to keep them stimulated. Oscar fish need a tank that is durable and is easy to fill and empty. It should have a solid bottom and as mentioned, they are fond of hiding places, so it is important to provide them with plenty of rocks, caves, and other hiding spots.

Water Parameters

Oscar fish require a water temperature of 77-80 degrees Fahrenheit (25-26 degrees Celsius) and pH levels of 6.8 to 7.2. They should also have a good amount of dissolved oxygen in their water and be kept clean. Oscar fish also need fresh water to survive. Make sure your Oscar’s water is clear and free of debris. Change your Oscar’s water every two days, and add a small amount of fresh water every time you change the main tank. Adding convict cichlid, Jack Dempsey, or other compatible Oscar fish will make the tank feel safer for them as they can form strong bonds with others in their group. You can test your water for chlorine, ammonia, and nitrate levels to ensure that Oscar fish are getting the ideal water conditions.

Diet and Nutrition

Oscar food must be high in quality protein such as white flake pellets or brine shrimp, you can mix them with other types of foods but they should always have some type of shellfish since they love it so much. Oscar fish are omnivorous and will eat a variety of foods, but they are especially fond of live and frozen plankton. They also enjoy small pieces of meat, such as fish flakes or cubes, as well as vegetables. Some people feed their Oscars a variety of live and frozen foods, but others simply feed them a diet of flakes or cubes.

Aquarium Maintenance

Their tank also requires maintenance because Oscars hate living without balance which is why they need not only food but also aquarium maintenance. Oscar fish are demanding when it comes to water changes. They need large amounts of clean, high-quality water which is kept at a temperature between 77° – 80° F (25° – 26°C) and are also constantly fed daily for them to stay healthy. Make sure the Oscars do not have any problems with their fins or skin before you first introduce them into the tank as some physical conditions such as fin rot or skin problems can be caused for them and require treatment in addition to regular tank maintenance.


Oscar fish can reproduce when they are the size of around 6 to 10 inches. The female Oscar carries its eggs in a brood pouch before releasing them into open water where they will take care of themselves until maturity occurs. After this happens, both parents tend to guard and protect their offspring throughout hatchling stages as a result of being solitary animals; once hatched, juvenile Oscars also spend most of their time alone which makes breeding easier for smaller groups but more challenging for larger groups.

Predatory fish close-up of the species Astronotus Okellatus, inhabitant of the southern tributaries of the Amazon

Tank Mates

While there are other freshwater fish that will do well with Oscars, their inclusion in a community tank should be done after learning about some of the bigger fish and making sure they would not eat them. Although wary to strangers, Oscar fish usually tend to form small groups so it’s best for your more aggressive water-dwelling friend to be introduced when a part of an established colony; also look into what type of compatible plants or substrate you can use as this will work better due to some of them not being safe with Oscars.


While the Oscars might prefer to swim free, they do like swimming by plants when not too tired and with a deeper substrate being beneficial; make sure that your type of water is spongy enough for them to sit on, allowing easy access as well as hiding an escape route in case it does need assistance. Some examples of suitable substrates are Java moss (Taxiphyllum barbieri), which comes from Asia and grows very easily, also known for providing a bright green color, and Vallisneria spiralis or the common name of eelweed is also usable for varying types of Oscars.

General Care Tips

Oscar fish are a popular aquarium fish and can be kept in a variety of setups. However, like all fish, they require some basic maintenance to keep them healthy and happy. Here are some more tips to help you keep your Oscar fish healthy:

  • Provide a well-maintained aquarium with plenty of room to swim and hide.
  • Feed your Oscar fish a varied diet that includes fresh vegetables and fruits, and quality pellets.
  • Monitor water conditions and change water as needed.
  • Use a quality filter to keep your Oscar fish clean and healthy.
  • Sanitize the outside tanks with a mild bleach solution when needed.
  • Include live plants to give your Oscar fish some extra hiding places and natural cover.