How to Care for Your Oscar Fish

Oscar Fish (Astronotus ocellatus) are a freshwater cichlid from South America and are also known as Peacock Cichlid, Walnut Cichlid or Velvet Cichlid. Oscars are a relatively large fish that grow up to sixteen inches long and can live for up to eight to twelve years if proper care is given. Read on to learn the steps for ideal Oscar fish care.

Setting up a Freshwater Tank

This is an important step, as this will be your Oscar’s home. The first step is to gather all the equipment you will need:

  • Freshwater testing kits
  • Cichlid Food and other cichlid care products (Water conditioners, buffers, substrates, trace element supplements)
  • Aquarium vacuum or siphon
  • Tank of proper size for your Oscar fish
  • Aquarium gravel (there are gravel blends especially for cichlids)
  • Aquarium heater
  • Filter
  • Fish net
  • Bucket for water changes
  • Ornaments or plants(either real or fake) for hiding places
  • Thermometer

Choosing an aquarium size

Oscar fish need at least 30 gallons of space each. The minimum tank size for a single Oscar fish should be 40 gallons.

Washing the aquarium

Everything must be washed. Hose out the inside of the aquarium thoroughly and then dry it with paper towels. Make sure to remove any soap residue. Rinse all equipment and ornaments you plan to submerge in tap water.

Place the gravel in a bucket and rinse it with water. Fill the bucket with enough water to submerge the gravel and stir until all of the loose sediment and debris comes off. Rinse and repeat this step until the water remains clear.

Finding a place for your aquarium

Oscar fish are sensitive to temperature fluctuations, noise and light, so keep the tank in a place where there will be minimal external influences on the environment. Place the tank away from doors, windows and vents and out of high traffic areas. Also, be sure to keep the tank out of direct sunlight as this promotes algae growth and temperature fluctuations.

Be sure to situate the tank on a sturdy piece of furniture or a special aquarium stand as a tank can weigh well over a hundred pounds when filled. To protect the floor and carpet, you can place a piece of corkboard beneath the stand or furniture as well as underneath the tank itself to keep the tank secure and even.

Filling your tank

If you’re using one, place your under-gravel filter on the bottom of your aquarium. (More on filters later.) Next, add about three to four inches of cichlid gravel. The amount of gravel is not pivotal, but there should be enough to support all decorations and plants.

Next, begin conditioning your water. Tap water should be left standing for 24 hours or use a water conditioner or stress reliever to remove contaminants and make your water suitable for fish. You can also use special products for cichlids that recreate the mineral content of their natural environment for optimal health. These elements will be important in your cichlid’s healthy transition to your aquarium.

Once your water is prepared, you can begin filling the tank. Pour the water in gently so as not to disrupt the gravel. You can also place a saucer in the bottom of the tank and pour the water directly into the saucer to avoid stirring up the gravel. Fill it up about halfway.
Once the aquarium is about half-full, add plants, ornaments, and rocks. Fill it up the rest of the way after these items are secure.

Bringing your Oscar Fish Home

The most jarring experience of your Oscar’s captive life will be the ride from the pet store to your home. Follow these tips to reduce the amount of trauma on your new Oscar.

  • If it is cold, prepare an insulated box to keep your Oscar in on the ride home.
  • Wrap the bag in newspaper or place it in a brown paper bag to reduce the amount it is exposed to. The transition from indoor light to outdoor light can be particularly shocking for an Oscar fish, as cichlids don’t like bright light.
  • Keep the Oscar away from heating vents and direct sunlight.
  • Make the trip home as quickly as possible. The less jolts from the car ride, the better.
  • Once you get the Oscar fish home, place the bag in the water without opening it for about 15 minutes. Next, add water from the aquarium to the bag a little at before opening the bag and setting it free.

Keeping the Tank Clean and Comfortable for your Oscar Fish

Keep a close eye on your Oscar fish’s water temperature with a digital aquarium thermometer. Oscar fish prefer temperatures between 74 degrees Fahrenheit and 81 degrees Fahrenheit with an ideal around 77 degrees. Avoid fluctuations in temperature.

Ideal pH level for an Oscar fish is about 7.2, but Oscar fish are easily adaptable as long as the change is gradual. Keep an eye on the pH level of both the water in the tank and the water you are about to add for water changes using your pH test kit. If the pH level is drastically different, add only a little bit of new water each time or treat the water first using cichlid buffers.

Keeping several small filters is best for a larger tank, as it staggers the maintenance of the filters. You will at least want either an external power, canister or internal filter, combined with an inexpensive sponge or undergravel filter (or both) to ensure that you have enough surface area for proper biological filtration.

Performing a water change

Changing about 10 to 15 percent of the water is a simple way to keep the water clean and healthy (never change all the water in a big tank at once). Do this on a weekly basis by siphoning off a bit of the water and then siphoning new water back in. Make sure you condition the new water as you did when preparing the tank.

Be sure you remove water, even if some of the water has evaporated from the tank. Evaporated water leaves behind impurities that make the water harder and by simply “topping off” a tank you leave the impurities in.

Feeding your Oscar Fish

Oscar fish are primarily carnivorous, even preying upon smaller fish. In the wild, they prefer live foods, but even purchased live foods commonly contain parasites or other contaminants and it is safer (and easier) to feed them processed or frozen foods. There are special cichlid food blends that will provide a good stable diet, but you should regularly supplement these with freeze-dried worms or other organisms.

There are feeder goldfish on the market, but these fish are not very nutritious and could carry disease.

Blended beef heart, earthworms, shrimps as well as cichlid pellets, peas and lettuce are all good alternatives to keep your Oscar on a balanced diet. An Oscar needs a variety of foods with high protein in order to stay healthy.


It is extremely important not to overfeed your Oscar fish. Oscar fish produce a lot of waste as it is and adding excess food can cause problems related to pollution, like ammonia buildup. Only feed the Oscar fish as much as it can eat in about two minutes. Any food left uneaten should be removed, along with any other floating debris you spot.

Breeding Oscars

Breeding Oscar fish is typically easier than breeding most other fish. Keep the water clean and raise the temperature to about 80 degrees Fahrenheit. The male and female will then begin the process of spawning.

Oscar fish will change colors and begin courting when they are about to spawn. Oscars will build mounds of gravel around the aquarium and will chase each other around the aquarium. Then the female will lay her eggs on a flat rock and the male will fertilize them.

Oscar fish usually lay about 1000 eggs at a time. Unfertilized eggs are white and fertilized eggs will turn transparent after about 24 hours and hatch within 2 to three days.

Feed the newly hatched fry brine shrimp and do 25% water changes every day to keep the conditions suitable for raising fry.

Be aware: sometimes the male will kill the female during courtship.

General tips on Oscar Fish Care

  • After setting up the aquarium, it is best to wait a couple weeks to make sure everything is in order.
  • Add only one or two fish at a time. Biological filters need time to accommodate new inhabitants and changes in the water.
  • Before adding an Oscar fish to a community, keep it quarantined in a separate tank for a few weeks to make sure it is healthy. A diseased fish could contaminate an entire population.
  • Oscar fish prefer hiding places. To keep them relaxed and happy, provide them with plenty of decorations and plants. Oscars prefer about half or more of the tank to be covered, so keep lots of hiding places for him.
  • Oscars prefer to live alone. If you must, choose other Oscars as companions with even temperaments. A passive Oscar is quickly bullied while an aggressive Oscar will attack other fish.
  • Do not neglect regular partial water changes.
  • Air pumps and air stones are necessary to oxygenate the water and release harmful chemicals by agitating the surface of the water.
  • Oscar fish and many cichlids do not like bright lighting. Use low intensity fluorescent bulbs in your hood or a fluorescent fixture – a 10,000K rating will provide the best viewing – or actinic lighting to avoid stressing them. Make sure to turn them off at night or supply a lunar light.
  • To avoid electrical shock, make a “drip loop” on all your cords. Hang a small weight in the middle of the cord so water will not travel down the cord and into the outlet.
  • Choose gravel that is free of dye and will not be swallowed. Cichlid gravels are your best bet.

17 thoughts on “How to Care for Your Oscar Fish

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  3. –You NEVER rinse anything with soap. Even if you rinse it off afterwards. Anything that previously was used with soap should not be used.

    — An oscar, BY ITSELF, requires at the BARE MINIMUM 55 gallons. Preferably 75. Two would require around 120 gallons, about TWICE the size you are recommending.

    –You need to CYCLE a tank first, and test the water before adding fish to make sure the process has completed. Just letting a tank ‘run’ for 2 weeks does nothing but waste electricity and push water around. You need to add a source of ammonia to the tank, through hardy fish or a fishless cycle, so that beneficial bacteria can establish itself in the tank and filter, and begin converting ammonia to its less harmful forms nitrite and finally nitrate, which is them removed through partial water changes. You don’t do this and you’re most likely going to have one dead oscar within a week or two.

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  6. Option one: Two fancy goldfishoption two:female (Not male! ) betta fish. otipon three:A mix of Kuhli loaches , and guppies. Option four:Platy fish. Five:Mollys six (community tank):Female bettas, Angle fish, a few mollys, and kuhli loaches.Many, MANY more. Just remember goldfish need twenty gallons for the first one, and ten gallons for each additional fish. and, the only fish that will get along with one of them are Kuhli loaches and Koi. Make sure you have a double power filter and check your water often I love animals.

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