Oscar Fish Care Guide: Tank Set Up, Temperature Needs, & More

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Expert advice for caring for, feeding, & breeding Oscar fish
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Oscar fish are a popular type of tropical cichlid that are super fun to keep as pets thanks to their playful and inquisitive natures. They're known to watch their owners intently, and some are even docile enough that you can pet or hand-feed them! Even better, they're relatively easy to care for. In this article, we spoke with aquarium specialists to learn how to set up an Oscar tank, what kind of requirements they need, what they like to eat, and how to breed them. Read on to learn more!

Caring for an Oscar Fish

Keep your Oscar fish in a tank that’s at least 75 gal (280 L). Oscars are tropical, warm water fish and sensitive to temperature fluctuations, so keep the water between 74-81°F (23-27°C). Add a water filter and feed your fish a varied diet of cichlid pellets, bloodworms, feeder shrimp, and krill.

Section 1 of 5:

Setting up the Tank

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  1. Provide your Oscar with at least a 75 US gal (280 L) tank . Although your Oscar may be very small when you first get it, it can actually grow to be 10–11 in (25–28 cm) in length, and sometimes even larger! To ensure your Oscar is comfortable, choose a tank that holds at least 75 US gal (280 L) of water. [1]
    • You can keep an Oscar fish in a tank that’s at least 55 US gal (210 L), but they prefer to be kept in larger tanks.
    • Size up your tank by about 55 US gal (210 L) for each additional Oscar you plan to keep. For instance, if you plan on keeping 2 Oscars in the same tank, get a tank that’s at least 130 US gal (490 L).
    • Aquarium expert Cyriac St.Vil says to always sanitize the tank before adding water and decorations. He recommends wiping it down with a solution of “one part bleach and five parts water.”

    Did You Know? Oscars can grow up to 1 inch (2.5 cm) a month, and they can live for 8-10 years!

  2. 2
    Keep the water between 74–81 °F (23–27 °C) with a heater and thermometer . Oscars, like most fish, are very sensitive to changes in water temperature. These tropical fish are happiest when the water is around 77–79 °F (25–26 °C), but they'll tolerate a range of 74–81 °F (23–27 °C). [2] Simply attach and run a 200W-500W heater, adjusting the settings as needed to keep the water temperature steady and warm. Then, aquarium specialist Craig Morton says to clip an external thermometer to the outside of the tank and check the temperature about once a day to ensure it stays within the acceptable range.
    • If the water is too cold, it can suppress your Oscar's immune system, leaving them vulnerable to illness. If it's too warm, it can deprive the fish of oxygen, which can lead to nerve and heart damage. [3]
    • Temperatures lower than 55° F (13° C) can be lethal to Oscars. In the wild, they can be found swimming in rivers up to 93° (34° C). So, don’t let their water temperature get past these limits. [4]
    • Oscars often destroy thermometers placed inside of their tank, which is why most aquarium specialists recommend using an external thermometer.
    • Check the manufacturer's information to ensure you choose the right heater for your size of tank.
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  3. 3
    Place a high-capacity water filter in the tank. Oscars are known for being really messy fish. They produce more waste than most fish species, and they like to rearrange their tanks, so they constantly stir up debris. While cleaning the tank is the only way to keep the water fresh, Morton says a high-quality water filter will go a long way toward reducing how often you need to clean.
    • A water filter also helps prevent the buildup of ammonia in the tank. Too much ammonia can stress your fish, causing them to lose their appetites and their color to fade. [5]

    Helpful tip: Choose a filter that is rated higher than the capacity of your tank. For instance, if you have a 75 US gal (280,000 mL) tank, you'd want at least a 100 US gal (380,000 mL) filter.

  4. 4
    Use gravel or coarse sand as a substrate. The choice of substrate is largely a matter of aesthetics. However, since Oscars are larger fish and produce a lot of waste, it's best to have a substrate that filters well. Morton says both gravel and sand allow water to sift through them, which washes out the waste so the filter can clean it up.
    • If you opt to use sand, make sure you choose coarse sand. This helps ensure that it won’t get sucked into the filter.
    • You don't have to use a substrate at all if you don’t want to. Just clean the bottom of the tank occasionally, as any debris that settles will be visible.

    Warning : Do not use a sharp or rough substrate. Oscars like to dig in the substrate, so anything sharp can injure the fish.

  5. 5
    Give the fish a few decorations to hide behind. Although Oscars aren't particularly shy fish, they'll be most comfortable if they have a place they can go to feel safe. Morton says driftwood , plants, rocks , and other decor are popular options for an Oscar tank. Oscars like to move around objects and rearrange their environments, so don't worry about placing them in the tank perfectly—they’ll likely get moved anyways! [6]
    • Your Oscar needs plenty of space to swim around, so don’t overfill the tank with too many decorations. 3 to 5 items is usually enough.
    • Choose heavy decorations and bury them in the substrate if you don't want your Oscar to move them around.
    • Note : Disinfect any decorations before you put them in the tank. St.Vil recommends submerging decorations in a mixture of 1 part water and 3 parts white vinegar for 1 hour. Then, “flush them with water,” “let [them] dry out,” and “flush them with water again.”

    Warning : Do not add sharp or rough decorations to the tank, as they can injure your Oscar if they push them around or get startled and dart into them.

  6. Slowly and carefully pour room-temperature tap water into the tank to prevent the substrate and decorations from moving around. Then, add conditioner to the water to remove chlorine and other chemicals—follow the directions on the bottle to add the right amount for your tank size. Simply cycle your tank for several weeks to allow beneficial bacteria to grow before you add your Oscar.
    • Cycling your tank involves adding ammonia to the tank and checking its levels until they decrease to 0.
  7. Adding your Oscar fish directly to the tank from the bag you brought them home in can stress them out or shock them, which is harmful to their health. So, Morton advises that you allow your fish to acclimate to the tank water by placing the bag they are in inside the tank for “15 to 30 minutes.” Then, use a fish scoop to remove your fish from the bag and place them in the tank.
    • According to Morton, “Do not ever put [the] bag water into your aquarium.” The water in the bag can potentially alter the ammonia levels and pH of the water or introduce harmful bacteria.
  8. Oscars like to jump, and sometimes they’ll even jump right out of the tank! In fact, a medium-sized Oscar can lift the lid right off of the tank if it isn't secure enough. So, Morton recommends choosing a lid that fits tightly onto the top of your aquarium to ensure that doesn't happen.
    • If your aquarium didn't come with a lid, write down the exact width and height measurements for the top. Then, visit your local aquarium supply store or pet shop.
  9. 9
    Introduce tank mates from a young age or move them to a new tank. Typically, Oscars do best when they're kept alone. However, if you want your Oscar to have a companion, try to introduce them as young as possible to increase the odds that they'll get along.
    • If your Oscar is already mature, try moving the fish to a new tank when you introduce them. That way, neither one becomes territorial.
    • You can provide 1 tank mate, or you can keep Oscars in groups of 4 or 5. However, avoid having 3 Oscars in a tank since 2 might bond with each other and leave the other one isolated. [7]
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Section 2 of 5:

Feeding Your Oscars

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  1. 1
    Feed your Oscar cichlid pellets once per day. About 80% of your Oscar's diet should come from high-quality cichlid pellets that contain whole fish, krill, or shrimp in the ingredients list. Oscars primarily feed on small insects and crustaceans in the wild, so they need food that's mostly made of meat. [8] To prevent overfeeding your fish, only feed them once each day. Aquarium specialist Marshall Stephens says adding no more than what “they can eat in about 30 seconds is a good starting point” for how much food to give them.
    • Ultimately, Stephens says how much food you give your fish is a “trial and error process.” He says a good indicator that you’re giving them too much is if the food “just goes right in the filter instead of to your fish.”
    • If you're not sure how much your fish will eat, drop in a few pellets and wait for the fish to eat them. Then, drop in a few more. Continue this for about 3 minutes. Once you get a good idea of how much your Oscar eats at each meal, you can drop it all in at once.
    • To ensure your Oscar gets all of the vitamins it needs, choose a pellet that also contains algae or green plant material. This can lessen the risk of your fish getting “hole in the head disease,” which is usually caused by nutritional deficiency. This disease causes abscesses to form on the fish's head and body.
    EXPERT TIP

    Cyriac St.Vil

    Aquarium Expert
    Cyriac St.Vil is an Aquarium Expert and the Director of Learning Through Nature based in Brooklyn, New York. With over 26 years of experience working with aquariums, Cyriac and the Learning Through Nature team have created aquariums in classrooms, lobbies, and dining halls for viewing and educational purposes. He has extensive knowledge of aquarium maintenance and care, making science fun, and building living habitats.
    Cyriac St.Vil
    Aquarium Expert

    Overfeeding your fish can lead to a dirtier fish tank. Instead of feeding your fish a whole bunch of food, add fish food to the tank as they eat it. This helps you to ensure that most of the food doesn't fall to the bottom of the tank.

  2. 2
    Supplement your Oscar's diet with seafood and insects. About 20% of your Oscar’s diet should be made up of fresh, frozen, or freeze-dried insects, seafood, and worms. Some of their favorite foods are bloodworms, feeder shrimp, krill, crickets, and mealworms. You can find these at a well-stocked fish supply store, or you can even use food that's packaged for humans! [9]
    • Oscar fish are technically omnivores, and in the wild, they eat algae, plants, and fruits. However, they much prefer meat. [10]

    Did You Know? Oscars aren't picky eaters—they'll eat almost anything you give them! However, you should pay close attention to their food to ensure they get a balanced diet.

  3. 3
    Don't give your Oscar feeder fish. Oscars will eat live prey, but that doesn't mean that giving them live fish is good for them. Feeder fish aren't nutritionally healthy for your fish, and they can sometimes spread intestinal parasites that will make your Oscar very sick. [11]
    • Not only do feeder fish lack the nutrition your Oscar needs, but they can also create additional problems. For instance, feeder goldfish contain high levels of an enzyme that will destroy the vitamin B1 in your Oscar's system.
  4. 4
    Avoid feeding animal meat to your Oscar. Although Oscars are carnivorous, they shouldn't eat meat from land animals. Animal meat is very high in saturated fat, which fish can't process well. While small amounts probably won't do a lot of harm, there are much better options for food to give your Oscar.
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Section 3 of 5:

Maintaining the Tank

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  1. 1
    Change 10-15% of the water in your tank every week. Since Oscars are so messy, regularly cleaning their tank is essential. Morton says the best way to keep the aquarium fresh is to take out about 10-15% of the water once a week. Then, replace that with fresh, conditioned water.
    • For example, if you have a 100 US gal (380 L) tank, you would change 10–15 US gal (38–57 L) each week.
    • This is a gentle way to clean since it maintains the environment that the fish are used to.
  2. 2
    Use a water testing kit to keep the pH between 6 and 8. Most fish prefer a relatively neutral environment, and Oscars are no different. [12] About once a week, use a test kit or pH test strips to measure the acidity of the water. If the pH is too high or too low, you'll need to remove the fish and adjust the pH . [13]
    • If the pH is too low, or the water is too acidic, add 1 tsp (7 g) of baking soda for every 5 US gal (19,000 mL) of water. [14]
    • If the pH is too high, or the water is too basic, place a clump of peat moss in a mesh bag and place it inside of the water filter. You can buy clumps of peat moss at an aquarium supply store. [15]
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Section 4 of 5:

Breeding Oscars

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  1. 1
    Purchase a breeding pair of Oscars or raise juveniles together. It can be really hard to sex Oscar fish, so the best way to get a breeding pair is to either purchase a pair that has already successfully bred or to raise a group of Oscars together so they can pair up naturally. [16] If you plan to raise your own breeding pair, be aware that it can take them 1 to 2 years to fully mature. [17]
    • Females have a cone-shaped tube near their anal fin, known as the egg tube. However, this stays retracted most of the time. Males have a thin spike, which they use to fertilize the eggs.
  2. 2
    Change 20-30% of the water when you're ready for the fish to breed. In the wild, Oscars breed during the rainy season. However, they sometimes need help when they live in captivity. By changing more water than normal, you can help signal to the Oscars that breeding season is coming up. [18]
    • Morton recommends doing this at the same time as your normal weekly cleaning to avoid changing too much of the water at once since you don't want to stress the fish.
  3. 3
    Lower the temperature in the tank by 3-4°F (2°C). The rainy season in the wild typically corresponds with cooler temperatures. To replicate this effect, lower the temperature on your heater slightly. [19]
    • Don't drop the temperature any more than this, or you could shock your fish.
  4. 4
    Sprinkle water on top of the tank for 5-10 minutes a day. If you really want to encourage your fish to breed, spend a few minutes a day recreating rainfall on top of the fish tank. You can either use a watering can to create rain by hand, or you can install a spray bar just above the water and let it run for a few minutes once a day. [20]
    • Make sure to condition the water and remove any chlorine before you add it to the tank.
    • You can find spray bars wherever aquarium equipment is sold.
  5. 5
    Watch the fish for breeding rituals. Sometimes, Oscar breeding can look aggressive. Your fish may slap tails, chase each other around the tank, or lock mouths with each other. However, these are actually signs that your fish are breeding, and you're likely to see eggs soon. Once the female is ready to lay eggs, you might even notice her cleaning off a flat surface on the bottom of the tank or a rock. [21]
    • Female Oscar fish usually lay their eggs directly on the substrate or another flat surface. Then, the male will come over to fertilize them.
    • Once the eggs are fertilized, you might notice both the male and female guarding the eggs.
  6. 6
    Set up a fry nursery once you see eggs. A female Oscar can lay up to 1,000 eggs at a time, although this number is often much lower than that. [22] Once you see the eggs, start preparing a separate tank because the eggs only take about 3 days to hatch. Use water from the parent tank so you don't shock the fry when you move them.
    • Don't be alarmed if you see the pair eating some of the eggs. They do this to remove deformed or unhealthy eggs from the batch.
    • Right before the eggs hatch, you may see them shaking slightly as the fry tries to break free.
  7. 7
    Move the newly hatched fry to their own tank. Once the fry are hatched, the parents will sometimes eat them. To avoid this, gently scoop the fry up with a net and move them to their separate tank as soon as possible after they hatch. [23]
    • It usually takes 3 days for the fry to hatch from the eggs.

    Caution: The parents may try to protect their eggs, so watch your fingers!

  8. 8
    Feed the fry baby brine shrimp after they're 4 days old. The fry will still have a yolk sac hanging from them when they hatch. This typically stays for about 4 days, and it will feed them during this time. After the yolk sacs disappear, give the fry baby brine shrimp about 3 times a day. Give them a small pinch of the shrimp, and if they eat all the food within 2 minutes, you can give them a little more. Continue this until the fry reach 1–2 in (2.5–5.1 cm) long. [24]
    • Remove any uneaten food from the nursery before you feed the fry again.
    • Once the fish reach about 1–2 in (2.5–5.1 cm) long, they're ready to find a new home!
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Section 5 of 5:

Frequently Asked Questions

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  1. No, Oscar fish can not survive in cold temperatures. Temperatures at and below 55° F (13° C) can harm them and lead to death. [25]
    • In temperatures below their normal range (74–81 °F (23–27 °C), Oscars can grow lethargic and get sick.
  2. Oscar fish thrive in warm waters. So, their ideal water temperature is between 77–79 °F (25–26 °C). In the wild, they often swim in waters between 73-93° F (23-34° C). [26]
  3. Oscar fish usually prefer to be solitary or live in pairs. However, they do get along with medium-sized tropical fish. Some good companions include plecos, Jack Dempseys, silver dollars, and other South American cichlids. [27]
  4. How many Oscars you can keep in a tank depends on the size of your tank. Generally, each additional fish you add to your tank needs 55 US gal (210 L) of water. [28]
    • Oscars can get aggressive if they’re kept with too many fish. If you notice any bullying behavior, give the fish their own tank.
  5. Oscar fish are known for having expressive and intelligent personalities. These fish often recognize and greet their owners. They can learn tricks and even sometimes wag their tails. They can also get moody and sulk or destroy their cages. [29]
    • In fact, Oscars are often referred to as water puppies! Like puppies, they have playful and unique personalities.
  6. Oscar fish are native to South America (Venezuela, Peru, Colombia, Bolivia, Ecuador, Brazil, Guyana, Argentina, and Paraguay). They mostly live in warm rivers and basins, such as the Amazon River. [30]
    • Oscar fish have also been introduced to Australia and the United States, so you may find them in the wild if you live in these countries.
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  • Question
    Is it okay to feed frozen shrimp to my oscar?
    Community Answer
    Shrimp may be fed as an occasional treat. You can soak the shrimp in fresh water to help thaw, it as well as leech out some of the salt.
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  • Question
    Can I feed my Oscar fish frozen shrimp that contain salt and E451?
    Community Answer
    Shrimp is okay for your Oscar as an occasional treat. You can soak the shrimp in fresh water to help it thaw and eliminate some of the salt.
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  • Question
    Does an Oscar eat hatched Oscar fry?
    Community Answer
    Yes, it is very likely that a male will eat the fry. Therefore, you should keep them in separate tanks.
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      Expert Interview

      Thanks for reading our article! If you’d like to learn more about caring for fish, check out our in-depth interview with Craig Morton .

      References

      1. ↑ https://advancedaquariumconcepts.com/oscar-fish-care-guide/
      2. ↑ https://modestfish.com/oscar-fish-care/
      3. ↑ https://fishkeepingadvice.com/oscar-fish-care-guide/#
      4. ↑ https://dergipark.org.tr/en/download/article-file/417889
      5. ↑ https://fishkeepingadvice.com/oscar-fish-care-guide/#
      6. ↑ https://fishkeepingadvice.com/oscar-fish-care-guide/#
      7. ↑ https://fishkeepingadvice.com/oscar-fish-care-guide/#
      8. ↑ https://modestfish.com/oscar-fish-care/
      9. ↑ https://modestfish.com/oscar-fish-care/
      1. ↑ https://dergipark.org.tr/en/download/article-file/417889
      2. ↑ https://modestfish.com/oscar-fish-care/
      3. ↑ https://dergipark.org.tr/en/download/article-file/417889
      4. ↑ https://fishkeepingadvice.com/oscar-fish-care-guide/#
      5. ↑ https://modestfish.com/how-to-raise-ph-in-aquarium/
      6. ↑ https://www.theaquariumguide.com/articles/lower-ph-aquarium
      7. ↑ https://fishkeepingadvice.com/oscar-fish-care-guide/#
      8. ↑ https://dergipark.org.tr/en/download/article-file/417889
      9. ↑ https://fishkeepingadvice.com/oscar-fish-care-guide/#
      10. ↑ https://modestfish.com/oscar-fish-care/
      11. ↑ https://fishkeepingadvice.com/oscar-fish-care-guide/#
      12. ↑ https://dergipark.org.tr/en/download/article-file/417889
      13. ↑ https://dergipark.org.tr/en/download/article-file/417889
      14. ↑ https://youtu.be/iMGeND3zETk?feature=shared&t=813
      15. ↑ https://youtu.be/iMGeND3zETk?feature=shared&t=839
      16. ↑ https://dergipark.org.tr/en/download/article-file/417889
      17. ↑ https://dergipark.org.tr/en/download/article-file/417889
      18. ↑ https://fishkeepingadvice.com/oscar-fish-care-guide/#
      19. ↑ https://modestfish.com/oscar-fish-care/
      20. ↑ https://modestfish.com/oscar-fish-care/
      21. ↑ https://dergipark.org.tr/en/download/article-file/417889

      About This Article

      Article Summary X

      To care for an Oscar, keep it in a tank that's at least 55 gallons since they can grow a lot. If you want to keep more than 1 Oscar, introduce them at a young age or in separate tanks so they're less likely to be territorial. To feed your Oscar, give it mostly commercial cichlid pellets, and supplement its diet with fresh or freeze-dried insects, seafood, and worms. You should feed your Oscar once a day, and only feed it as much as it can eat in 2-3 minutes. To learn how to breed Oscars, scroll down!

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