Freshwater Fish

Oscar fish (Astronotus ocellatus): Care guide in the aquarium

The Oscar fish (also known as the velvet cichlid) is an extremely popular freshwater fish in the aquarium community. They are beautiful and their mannerisms make them quite fun to watch.

However, there are a few things you need to know about Oscar fish care if you plan to own one.

You see, these fish are quite aggressive and can quickly cause trouble if you intend to keep them with other fish. This is why we always recommend that you have some experience as an aquarist before getting one.

But don’t let us discourage you! Oscars can be incredibly rewarding aquarium fish to care for, and once you know what you’re doing, it’s pretty straightforward.

That is why we wanted to put together this care guide. In it, you will learn everything you need to know about Oscar fish care and useful facts about the species.

Species Summary

Oscar fish come from South America, namely Peru, Brazil, French Guiana, Colombia and Ecuador. Its scientific name is Astronotus ocellatus (if you’re curious about that sort of thing).Large numbers of these fish can be found in the Amazon River Basin and they prefer slow-moving waters with lots of rocks and debris.

Although they are naturally from this area, you can also find them in Australia, China and even Florida. The Oscars found here either escaped during the transit of the fish trade or were dumped by owners who failed to care for them.

They are known for their stunning appearance, unique personality, and aggression.

Oscar Fish Lifespan

The average lifespan of the Oscar fish is between 10 and 13 years. However, an Oscar with great genetics and good care can live for more than 15 years.

Their lifespan is often overlooked by potential owners, and once they learn this they are often impressed. When you compare this to other related fish like the African Cichlid, there is a big difference in age.

In our opinion, this is one of the biggest benefits of getting an Oscar fish. We love the idea of ​​owning and caring for them over a long period of time.

In our experience, the bond and attachment you create when you have a fish for so long really makes the experience that much more rewarding!


Oscar fish appearance can vary between types, but they all look fantastic. The beauty of this tropical fish cannot be said enough!

The general body type of these fish is quite long and egg-shaped. Like many other cichlids, their tail fins are fairly symmetrical and standard, not protruding too far.

Their dorsal fins extend into their tail fins, giving them a stocky sort of look. The same goes for their anal fins as well. This makes them look like fat torpedoes in the water.

Their eyes are large and usually surrounded by a colorless body patch that extends to the beginning of the dorsal fin.

Types of Oscar Fish

Below we have listed the different types of Oscar fish and what they look like.

Oscar tiger fish

This is the classic color pattern seen at most Oscars. As you probably know from the name, the tiger Oscar fish is black and orange.

Unlike tigers, they do not have orange stripes (or are they black stripes?) and instead have a more sporadic pattern. They have a black body with orange lines and spots that spread out in random directions.

It looks like a cross between a Rorschach test and a maze. Its body is usually free of color from the upper lip to the beginning of the dorsal fin.

red oscar fish

Red Oscar fish are exactly that, red. The red coloration is found primarily on the sides and, unlike the tiger variation, is hardly patterned. They are mostly solid red on the side with no color on any of their fins.

albino oscar fish

Like many other species in the aquarist community, albino Oscars are highly sought after due to their unique appearance. With albino Oscars, the red color on the side is usually more spread out than the orange on Tigers. It’s also more of a «big shape made of dots» type of design.

As you probably guessed, the main body color of the albino Oscar fish is white. We’ve had the chance to see a few of these over the years and they definitely steal the show when you’re looking at a tank!

black oscar fish

Black Oscars are another type of fish that is on the rise lately. They have a very similar side pattern to the Albino but instead, the colors are 100% stealthy.

Black and gray are the dominant colors and give them a unique look, especially when compared to the flashier alternatives offered by other types.

Oscar Lemon Fish

The Lemon Oscar fish is basically the same as the Red Oscar, only yellow. The color patterns on its sides follow the same kind of rhythm, only it’s made with different colors.


The average size of the Oscar fish is between 10 and 12 inches long when in captivity. When in its natural habitat, this fish can exceed the 14-15 inch mark.

Due to their large size, you need to ensure that Oscars have adequate space to thrive and live a comfortable, stress-free life. We cover tank sizing in the next section.

Oscar Fish Care

If you want to provide good care for your Oscar fish, there are a few things you will need to do. While a large part of keeping this fish happy revolves around managing its temper, you need to understand the basics first.

Although these fish are hardy, you would never want to rely on that. Providing them with the best possible living environment should always be the goal.

tank size

The ideal size of the Oscar fish tank should be at least 55 gallons. These are large fish so they need a large tank that can accommodate them.

If you plan on keeping multiple Oscars, you will need to increase the size of the tank. Plan to add at least an additional 25 gallons of water for each new Oscar you add.

This means that for one fish you will need (at a minimum) a 55 gallon tank, 80 gallons for two, 105 gallons for three, and so on.

Making sure you have the right tank size should always be the first step in trying to provide great care for your Oscar fish. After all, this is the house they will live in!

If they don’t have enough space to be comfortable, their health will be affected by stress. Not only that, but the aggressive nature of this fish can be amplified when confined to a small space (not fun for anyone involved).

water parameters

Next, you want to make sure your water parameters are within the recommended guidelines. This will have a massive impact on the lifespan of your Oscar fish and ensure its health over time.

  • Water temperature: 75-80°F
  • pH levels: Between 6 and 8
  • Water hardness: 12-15dH

You won’t have to worry about filtration or fancy lighting, which makes Oscar fish care a little easier. A standard filter and light will work fine. You don’t even need to worry about air or water pumps to produce the required amount of current.

Lastly, make sure you are consistent when doing water level tests. Significant water changes can lead to serious health problems for your Oscars.

What to put in your tank

Having a good tank setup is also extremely important. Many inexperienced aquarists think that all they need to worry about are the water quality parameters, and putting too much effort into what goes into the tank is a waste of time.

We cannot express how wrong this is.

How you set up your Oscar tank will have a significant impact on its enrichment and stress levels over time. If you want them to be happy and healthy, pay close attention to this section!

  • Hideouts – It is important that you give your Oscar fish a place to hide so that it feels comfortable and safe. Rocks and driftwood are great options. Oscars aren’t picky though, so anything that serves as a suitable hiding spot is fine for them.
  • Plants – If you want to add plants to your tank, it’s usually smart to choose a plant that can float like Hornwort. They won’t be damaged by any of the digging that Oscars do and will grow like weeds no matter what you throw at them.
  • Substrate: You will want to make sure there is a soft substrate at the bottom of the tank. Oscars like to poke and stir the substrate from time to time, and you don’t want them to cut themselves while doing so.

hole in the head disease

There is one disease you’ll want to watch out for with Oscar fish in particular. It’s called hole-in-the-head disease and it’s definitely not something you want your fish to get.

Symptoms are one or two small holes in your Oscar’s head. These will worsen over time if left untreated, and will likely cause scarring after they have healed.

As scary as it sounds, Hole in the Head disease is something you can cure as well as prevent. Maintaining excellent water quality within recommended parameters will ensure that your fish do not contract this disease.

If you see that your fish is developing this disease then it is time for you to get to work. You will need to test the water and probably change the water in the tank if you find there are problems. This guide is a great resource that is included in every step of the process.

Food and Diet

When it comes to the best food for Oscar fish, you have several options to choose from. This is because Oscars are not picky about what they eat (they are omnivores)

In their natural habitats, Oscars typically eat insects, the occasional fish, and nibble on any plant they like.

In your freshwater aquarium, you will probably feed them a mix of processed and live foods. Most cichlid-friendly pellets or flakes are fine. For live food, two of the most common solutions are brine shrimp and bloodworms. You can even feed them live crickets and grasshoppers.

If you want to experiment with some additional foods to supplement your Oscar fish’s diet, there are a few other options. Some aquarists have experimented with occasionally feeding their Oscars nuts or fruit, but this is something you’ll want to limit quite a bit.

Frozen peas have also been reported to provide a nice boost of energy and richness of color in your fish (they seem to love them too). Again, this is the Oscar fish food you’ll want to reserve as a special treat.

behavior and temperament

Oscar fish behavior is something that can be misunderstood. When people hear that this fish is aggressive, they sometimes think that they are downright mean.

That is not the case.

Yes, the Oscars have the potential to be quite aggressive and territorial. However, this will normally only show if you have them in a sub-optimal tank environment.

Being too crowded or pairing them with tank mates who aren’t a good fit is a recipe for disaster. But if you’ve done your homework and have them in an environment where they’re comfortable, your Oscars can be pretty laid back!

Aside from their aggression, there is one Oscar fish behavior worth noting before we continue (we hinted at it earlier). These fish love to rummage through their substrate in an attempt to dig up some food.

This means you need to be prepared for them to occupy the middle (where they spend most of their time) and the bottom of the tank throughout the day.

Tankmates Oscar

With their potential for aggression, finding the best tank mates for Oscars is obviously a priority for many new owners.

If you want to play it safe, the best tank mates for Oscars are other Oscars. This is a fairly common rule when it comes to aggressive fish species.

All you need to do in this case is make sure you follow the minimum tank size protocols and you should be good to go!

Community Tankmates

If you want to keep your Oscars with tank mates of another species, you’ll have to be a little more careful.

Due to their aggression, the confined nature of a freshwater aquarium makes it difficult to completely guarantee that there will be no conflict (even if your tank size is large enough).

This means you’ll need to look for fish that are big enough to hold their own but don’t feel the need to fight.

Small fish like goldfish or guppies will get toasty if kept in a tank with Oscar. If you’re using them as feed fish, that’s another story of course.

Some good Oscar tank mates include:

  • bichirs
  • blue mite
  • jack dempsey fish
  • green terrors
  • silver dollar fish
  • Arowanas
  • chocolate cichlids
  • Demon Earth Eaters (awesome name btw)
  • fire mouth cichlid
  • black convict cichlids
  • plecos
  • striped cleft

As you can see, there are a lot of cichlids on this list of possible tank mates. This is because their feisty natures can usually cancel each other out and result in a peaceful coexistence.

Author’s Note: It’s important to monitor fish closely when you introduce them. Just like people, some are more grumpy than others. You may find that you have two tankmates who are too feisty to live together (even if they are of a listed species).

breeding tips

If you plan to breed Oscar fish, we wish you luck. These fish are extremely difficult to breed and require a lot of experience for you to pull off.

That said, it is possible to breed Oscars.

One of the challenges you will face early on when it comes to breeding Oscar fish is how picky they are when it comes to mate selection. This is usually what causes most playback attempts to stop.

One solution to this is to buy two fish that have already mated or grown together. The downsides to this are cost and time, but it’s your best bet if your current Oscars don’t match up.

To mimic the time of year the Oscars are held, there are a couple of things you’ll want to do. The first is to lower the temperature of the water a bit (a few degrees is fine). Doing some partial water changes every 2-3 days is also another way to stimulate the mating process.

If this works, you will see different behavior from your fish when they are ready to mate. There will be some flapping that seems a bit unusual at first. They may also open their gills a little wider than normal. If you see this, it’s a good sign, nothing to worry about!

In the breeding tank, you’ll want to make sure there are rocks available for them to lay their eggs on (before this process begins, of course). That’s because your Oscars will use the top of a rock as a place to lay their eggs.

Once this has happened, the pair will hover around their eggs until it is time to hatch. You may see the female moving some of the substrate to keep the eggs clean (very fun to watch).

After two or three days, the eggs will hatch and you will need to find a new home for the juveniles to help facilitate their growth. Feed them several times a day and monitor their growth. When they start to get too big, you’ll need to make sure they get a tank size upgrade so they can continue to grow normally.

It’s decision time

Now that you know more about Oscar fish care and their general temperament, it’s up to you to decide if you want to take on them.

In our opinion, some people in the aquarist community somewhat exaggerate the difficulty of caring for Oscars. There are definitely some things you’ll need to take seriously, but as long as you follow the recommended steps, you should be fine.

We think the advantage of owning an Oscar is well worth any consideration you have to make about its aggressiveness. They are a fantastic and beautiful fish that can be a lot of fun to watch.

If you have any suggestions on how we can improve this guide, we’d love to hear from you. Simply visit our contact page and get in touch!

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