What Is the Tank Size for Oscar Fish

When you get a new Oscar fish, it is important to know what tank size you will need for your pet fish. We have put together a list of the tank sizes available today and the suggested number of Oscars in it.

Oscar fish (Astronotus ocellatus) swimming underwater

What Tank Size Do I Need for an Oscar Fish?

There is no minimum or maximum tank size in relation to the number of Oscar fish you will be keeping. We recommend a 55 gallon aquarium for every 1 Oscar fish, though some individuals may require more than this as our pets become larger and/or active.

The most important thing that you should consider when thinking about the size of the tank for your Oscar fish is the number of Oscars that you have. In general, Oscar fish can be kept in a pair or small groups no larger than 5. In larger groups, they may become territorial and start to attack one another. You do not want any aggressions going on or you will have damaged fish that need to be fixed. In addition, you do not want to have more than 10 Oscars in a tank. It is just too many fish for the size of the tank.

Below is the list of the most common tank sizes and the recommended number of Oscars that you can house in it:

  • 5-Gallon Tank: Considered as the smallest tank size in the list, you can utilize this for a small Oscar fish. This tank size is commonly used as an aquarium for 1 Oscar fish no older than a year that is new in captivity. The downside of this size is that as soon as your Oscar fish begins growing, you will need to find a bigger aquarium to supply its needs. In addition, the tank is small and the amount of water that you can add to it will be limited.
  • 10-Gallon Tank: This is the most common size for an Oscar fish in captivity. While it is possible to keep 2 or 3 small Oscars in a 10-gallon tank, some experienced Oscar owners may find them crowded for their needs. Some experts also recommend keeping only 1 Oscar per 10 gallons of water. The downside of this size is that it does not allow enough room for your pet fish to grow as large as they may want to become. The 10-gallon tank is not a perfect size for your pet fish to settle in as they grow. Hence, we suggest only putting 1 average-sized Oscar fish no longer than 5 inches in this tank size.
  • 20-Gallon Tank: One of the largest tanks that you can use for an Oscar (without having to resort to fake plants) and it allows room enough for at least 2 or 3 Oscars per living area if properly put together, with provision by making sure there are no edges or corners where food gets trapped inside which leads this fish ill . This tank size is a good one to start with and you will enjoy having your Oscar in it, which can grow up to around 8 inches long. However, just like other tank sizes, you will soon have to relocate your Oscars as soon as they grow or if a male and female had their offspring.
  • 30-Gallon Tank: The 30-gallon fish aquarium is the most common option for Oscars big enough to demand more than just 10 gallons space alone, particularly if they are not in breeding condition yet. A typical tank would house several fighters together unlike some of other options where only 1 or 2 Oscars could be kept. This tank size is again recommended for the breeders to raise their young and will also provide them with enough room to grow in.
  • 55-Gallon Tank: This tank size is the best for a fully-grown Oscar fish (11 inches to 12 inches). With this tank size, all the needs of your Oscar in terms of temperature, water hardness, oxygen and space will be well delivered.
  • 75-Gallon Tank: If you plan on getting a school of three or four Oscar fish, then we can recommend getting a 75-gallon tank instead. It is important to not overcrowd. In addition, you will need to add a filter for the 75-gallon tank, because Oscars have no way of swimming against the current.
  • 125-Gallon Tank: Five or more Oscars can also be kept in bigger tank sizes and can be combined with other cichlid species. It will be quite advantageous as you can keep many fishes at once which includes various kinds of fish species. Keeping these fellows together is cheaper than buying each in its own tank and keeping them solitary too (but they are much better companions if allowed to get their natural environment after all). The downsides here are that you will have to upgrade the tank as a whole, which may cost more. Again, depending on what size of Oscar fishes are meant for this space, choose one according to your budget and goals. Do not overcrowd by combining more than three species, and make sure the Oscars are kept together so they do not bully the others out of their places by territoriality. The best rule to keep any species of fish in the aquarium is not to mix them. However, you can combine Oscar Fish will many different types of fish such as tetras.
Oscar fish Astronotus ocellatus swimming underwater aquarium

Why Is it Important to Get the Correct Tank Size?

Many factors contribute towards good water quality and fish health but among these high-stress situations can be some of the most problematic. Providing a sufficient supply of oxygen, removing toxic substances from their environment, maintaining appropriate levels in their feed are all measures that require close monitoring. However there are also times when specific surface area requirements for certain types of fishes are critical.

Frequently Asked Questions (FAQs)

Q: What is the minimum tank size for 1 fully-grown Oscar?

A: The minimum tank size for this species is 55 gallons. This number falls in with the recommended range on most of the online forums and resources (but it should not be confused as a numbers only statistic).

Q: What size tank do I need for 2 Oscar fish?

A: You can house 1 Oscar fish in a 55-gallon tank, 2 Oscars need to be housed in a bigger tank (75-gallon aquarium).

Q: What are the best tank mates for Oscars?

A: Oscar fishes are usually very peaceful, so do not fear for their well-being when combined with other fish. You can house them with small community tank mates or larger ones as long as the biological and physical needs of all parties are at least taken care of before housing. This includes a filtration system tailored to accommodate each individual issue, proper temperature and general overall water quality monitoring systems that work on a regular basis.