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The Complete Oscar Fish Care Guide|Oscars A Long & Healthy Life

In this post, I’ll give you a full guide on keeping Oscar fish and an easy guide on Oscar Fish Care. They are one of the most popular freshwater fish among aquarists. Oscar fish belong to the Family cichlid and belong to the genus Astronotus . There are two species in the genus Astronotus, and they are  Astronotus crassipinnis (Heckel, 1840) Astronotus ocellatus (Agassiz, 1831). The common or aquarium verity is A. ocellatus. Oscar fish are also known as marble cichlid, velvet cichlid, and tiger Oscar. A. ocellatus had discovered by Louis Agassiz in 1831 first named Lobotes ocellatus by mistaking it for a marine fish. But after a lot of work, the species was put under genus Astronotus as A. ocellatus

Oscar Fish Care

Native Distribution and Habitat of Oscar fish

Ocellatus or Oscar fish is native to Peru, Colombia, Brazil, and the Amazon region. Oscar fish live in freshwater fish that come from South America and can typically be found in the Amazon and Orinoco river basins. They make their home in both rivers and lakes as natural habitats. The natural habitat of Oscar fish is typically found in long, shallow pools of water where they can find plenty of food to eat nearby. They also need to live at a certain temperature; if it is too cold, they will not do well. This fish cannot live lower than ~12.9 C habitats.

Oscar Fish LifeSpan

Different fish have different lifetimes. For Oscar fish, it is generally 8-13 years. Having an aquarium can be time-consuming and difficult, but if you take the right care of them, Oscar fish can live up to 15 years.

Oscar fish behavior

Oscar fish are very territorial and aggressive towards other Oscars. It is in the best interest of the tiny fish to defend their territory in order to avoid being chased away or attacked by other oscar fish. However, when they are in a group, the aggression reduces significantly. Tiny fish are at risk of being chased away or attacked by other, larger fish. If they stand their ground and defend their territory, it will be less likely that the larger fish will bother them. However, when they are in a school of fish, the aggression reduces significantly.

Oscar Fish behaviour

Why is the Lifespan of Oscar Fish so Short?

The lifespan of the Oscar fish is very short in captivity. Because there are also other factors that can be attributed to their life expectancy in captivity. One reason for their short lifespans is the amount of stress they are put under in an aquarium. This stress can come from being unable to move, being confined in a small area, or just being overcrowded with other fish. These conditions are also not suitable for an Oscar fish to breed or feed well, which all play into the lower lifespan of Oscars compared to other types of tropical fish.

Oscar Fish Identification

These fish grow up to 12 inches, and they reach their maximum body length quicker than other fish species. They are long and oval. Their dorsal fin extends from the head to the caudal fin. In their native habitats, adult Oscar is dark-colored with yellow ringed spots at end of the body and around the dorsal fin. Juvenile Oscar fish is striped with white and orange wavy bands and has spotted heads. There are few Oscar varieties created using selective breeding

  • Red lemon Oscar fish- their body can be either red or orange, and their fins are black or white in color.
  • Albinos – This variety is without color pigments in their bodies.

Preparing Oscar fish Aquarium And Care

Oscar fish is one of the most popular species in the freshwater aquarium trade. They have unique characters which made this fish popular. Those characters are,

  • intelligent fish
  • Beautiful Coloring
  • Playful behavior
  • Fast-growing rate

Fish Tank preparation for Oscar fish

Oscar fish is large freshwater fish. They usually grow around 12 inches long. They need a big tank set up to swim in. Otherwise, the fish can be stressed. You should provide them with a comfortable environment. There are a few things to remember before choosing a fish tank for oscar fish care

  • For two fish you at least need a 130-gallon aquarium—this space is enough for two Oscar fish to swim easily.
  • Waste production is another problem for Oscar. They produce more waste than other fish. So keeping them in the smaller or crowded fish tank again made them stressed and causes diseases.
  • The tank should be big and bigger means a lot of weight or pressure on the tank stand. Keep that mind in when building your tank stand.

Filter setting

Oscar rearing tanks need a high-quality filter system to maintain water quality. Oscars are messy fish in nature. They produce a lot of waste during the day. To keep up the water quality, a big filter is needed. It is preferable to use a strong current generating filter to keep the tank in a more natural condition. Moreover, the filter should be able to do

  • Remove ammonium-like chemical agent generated due to fish waste
  • Maintain an excellent physical environment in the tank by removing physical particles (remaining food ) from the tank
  • Maintain oxygen level in the water

It is essential to keep in mind to buy a filter that you can afford and follow all the instructions when you are installing it. Apart from that always turned on your filter after introducing fish to the tank.

Tank hood and lighting

Oscar is a very active fish. There are many reports which tell us Oscar are really good jumpers and they can jump out of the tank if there is no hood in your tank. Therefore when preparing the tank, be sure to attach a good and affordable hood. The tank hood should not be too heavy and too light. In the native environment, when dead leaves and dust particles are gathered on the surface of the water that attracts smaller fish. That same effect is created by moistened tank hood. Water drops in the wet tank hood mimic small fish, and the tank hoods can drop out when Oscar tries to attack them. Therefore it is good to keep the underside of your tank hood clean without water droplets.

Tank Accessories for Oscar Fish

To resemble their native habitat, it is wise to fill the bottom with soft sand. Oscar fish like to dig holes in the bottom in search of food. If you put coarse sand, that will damage their soft tissues. As a next step, you can decorate them as you like. But there are a few things to keep in mind.

  • As mentioned earlier, these fish are messy and like to dig. Therefore securely attached all decorations to the bottom. Oscar is a big fish, and they can easily lift small rocks and plants.
  • When talking about plant decoration, it is wise to use floating plants over rooted plants. A good example is Hornwort. Another option is adding plastic plants.
  • Place a few hiding places in the corners. These are territorial species. So they need some hiding places inside their territory.
  • Securely place any other decorations to the bottom.

Water quality in the tank for Oscar Fish care

Oscars are from tropical waters. Therefore they prefer a warm water environment. The preferred water temperature for Oscar varies between 22- 25 Celsius (72-77 Fahrenheit). If you are from a tropical country, you can use water with an aquarium heater. But if you are from a temperate country you need a heater for your Oscar tank. Glass heaters are not suitable for Oscar tanks.

These messy fish are known to break them. Shatterproof tank heaters are ideal for this kind of situation. water parameters such as pH are another critical water quality parameter when maintaining a fish tank. Oscar, they prefer to live in slightly alkaline waters. The water should be at pH 7.2 for the best condition. more on tank pH. A clichéd fish lover you should use a clichéd buffer or a water conditioner to maintain water quality. You should measure the water temperature and pH of the tank using proper test kits.

What do Oscar fish eat?

Oscar fish are omnivores, so they will eat just about anything. They will eat both meat and plant-based foods. While most people feed them flakes or pellets, they can also feed them live food like bloodworms, brine shrimp, feeder fish, and earthworms. The next important factor, when rearing Oscar fish is how and what to feed them. Oscar is not a selective eater. They eat whatever you feed them. But it is your responsibility to keep a balanced diet.

As you already know, Oscar is a big fish, and they need more food than smaller fish. So if you treat them as other small fish Oscars will stave. If you feed them more than needed tank water quality will change very easily. And it is not only the amount of food quality of the food that should be considered.

In the wild Oscar feed on small live insects or small crustaceans (feeder fish). That means their diet should contain protein (from the small animal), and plant materials (from the animals they eat). You can feed them with live food. But it is safe to feed processed fish food with occasional live food addiction. Oscar also needs vitamin C.

In wild they get this vitamin C from the plant material they ingested from an animal they eat. You need to provide that missing part of their diet as an algae supplement. Rotate their menu now and then and feed them with various food such as blood worms, frozen peas, or brine shrimps. They will love that.

Although Oscars feed on live prey in the wild, many modern hobbyists avoid feeding live fish to them in an aquarium setting. These feeders can carry parasites or diseases that may adversely affect your Oscars or other tank inhabitants. If you’re using live feeder fish, confirm they’re high-quality and healthy. Remember that what goes in must come out so feed them appropriately.

Read more Do Oscar Fish Have Teeth?

Breeding Oscar Fish?

You may skip this part if you do not wish to breed Oscars. But it is interesting to know how you can breed them just in case. But keep in mind Oscar is one of the hardest fish to breed in aquariums.

Oscar Fish breeding

They do not pair easily. You cannot introduce any male and female oscar fish into the tank and expect them to pair. They are very picky when choosing mates. There are two established methods for breeding Oscar in tanks

  1. Buy already paired Oscar fish directly from an aquarium.
  2. Buy a group of juvenile fish and let them choose their mate with time.

These two methods have their ups and downs. The first method is expensive. You already know pairing Oscar fish is hard and you have to play nicely for the already paired couple. The second method is less expensive, but you have to wait until they grow into adults. It will take approximately 1 -2 years. If you can wait that long, that is the best option.

Like most other fish, Oscar stimulates their breeding ability in the rainy season. In the natural world, they have natural rain. But in your tank, you have to create a rainy environment. Here are some simple things you can do to mimic the rainy season in your tank

  • Lower the temperature by few degrees.
  • Sprinkle water in the surface of the tank each day.
  • Change the breeding tank water every third or fourth day.

When they are ready to mate, you can see the fish burst their operculum and wager their fins. This movement is to signal their mate to indicate that they are prepared to mate. Then pair will clean a rock surface to lay the eggs. Female Oscar fish can lay up to 3000 eggs. Oscar is a good and protective parent. Mother Oscar usually fans the egg with her fins to keep the egg surface clean while the father guides the territory. The parents keep this behavior until the egg hatch. That will take 2-3 days.

After the egg hatch, remove juvenile Oscars from a small tank and feed them at least four times a day to boost their growth. Do not let the tank be cloudy with excess food particles. You can move them to a bigger tank after they grow a little bit.

credits to sunil shrestha

Oscar fish common diseases

Oscar is normally a hardy fish. They did not get sick easily. If you keep your tank clean, your Oscar fish will be fine. But there is one disease common among Oscars, and that is “Hole in the head disease”. Another name for this disease is Freshwater head and lateral line erosion (FHLLE). You can easily identify this disease by its appearance.

What Is Hole in the Head Oscar?

If your Oscar gets this disease, there will be hole-type lesions mostly in the head or body of the fish. If not treated in the primary stage, this disease can be lethal to your fish.

Oscar Fish hole in head

In the secondary stages, the holes become bigger, and bacteria or fungal infections can occur. In severe cases, fish become ill and stop eating. There are several reasons for the disease, such as lack of proper nutrients or poor water quality.

Symptoms of Hole In The Head Disease

Symptoms of the condition include light, shallow pits on the head & lateral line. These will worsen if the conditions that caused them are not changed or treatment is not started. These holes may become deeper and lead to infection with exposure to secondary microbial & fungi.

These lesions can eventually create a severe infection and the fish becomes systemically ill with loss of appetite Symptoms may include pitting-type lesions on the head or lateral line.

Also, it can be caused by lower oxygen levels in the water. If changes are not made to the environment and treatment is not started, it will worsen into holes that are larger with secondary bacterial or fungal infections. death.

Causes and Treatment for Hole In The Head Disease

Check and correct water quality

If you see Hole Head Disease developing in Oscar fish, the first thing to do is carry out a water quality test that includes ammonia, nitrite, nitrate & pH test. This should be done soon as possible using a test kit. A hole in the head is most often caused by water conditions and is very uncommon for fish to develop the disease without a reason.

One risk factor for Hole Head Disease is a change in water temperature, so the fact that there was a change in temperature could have been the cause of the disease. If you find that there are high levels of toxins in the water, it is important to act quickly in order to remove them. This can be done by carrying out a large water change to reduce the concentration of toxins as much as possible.

Also, you can use “Prime.” It Not only eliminates chlorine but also detoxifies ammonia and nitrite. It’s important to realize that these substances that “remove” ammonia don’t actually remove ammonia.

Ammonia (NH3) turns into ammonium (NH4) when certain bacteria are present. This change is more toxic to humans but less toxic to plants and fish. As long as you keep your ammonia and/or nitrite levels at zero by carrying out regular water changes, the negative effects of ammonium exposure should be minimal.

Also, high nitrate levels can stress your fish, leading to illnesses such as Hole in the Head Disease. We recommend keeping nitrate levels under 40 ppm with frequent water changes.

Some early signs of Hole in the Head Disease can be relieved by updating your tank and doing your water changes. To relieve some symptoms, make sure you don’t have any toxins and that your nitrate is always low. For more severe Hole in the Head cases, metronidazole may be needed. This oral medication comes as a tablet or liquid dispensed to be taken by mouth.

A Healthy Diet

the best method for keeping holes in the head disease at bay is to keep your aquarium in the best condition! Please ensure that the water in your tank is changed often and heated to the proper range for this type of fish. In addition, filter the water before adding your aquarium of deceased fish.

You need to monitor the water chemistry. One important factor is the nitrate level — if it is too high, you can get “hole in the head disease” as a result. In the fight against Hexamita, vitamins are an important factor because it improves the immune system. As such, you should strive to improve your Oscar’s diet and make sure they get well-balanced nutrition.


Hexamitiosis is a disease that can be caused by excessive parasitism of flagellated protozoa called Hexamita. It has three causative species: Hexamita salmonis, Hexamita ertsii, and Hexamita early. Metronidazole is the most common treatment for a hole in the head disease in fish, but it can only be obtained from a vet’s office. vets will offer medicated fish food or a mixture that you add to your fish tank.


when it comes to hole in the head disease in fish, the disease is more prevalent in aquarium-bred species than in wild ones. This might mean that it’s simply an issue of poor care or hygiene. Aquarium species than in wild populations. This might indicate that it’s simply due to poor care and/or less hygiene, not environmental factors.

There is a parasite that can live in fish without hurting them, but it usually only develops this disease when the fish’s immune system is weakened by other factors.

Sensory pits vs hole in the head

Some people are surprised to notice little pinprick holes on their Oscars or on photos they took using a flash. Skull fractures often heal on their own, particularly if they are linear. They may take many months to heal, but any pain should decrease within 5-10 days. Oscar has two small holes just above its eyes. This is completely normal and should not be mixed up with a hole in the head disease.

Oscar fish tank mates

Oscars are large, active fish that need a lot of space to swim in. We recommend one large tank mate per 3-5 Oscars. If you are keeping the Oscar as the only fish, there is no need for a tank bigger than 30 gallons. However, if you have other types of fish with the Oscar, it might be worth considering a bigger tank. Tanks over 100 gallons would be more appropriate in these cases.

Fish that can live well with Oscars are rainbowfish, plecostomus catfish, swordtails, convict cichlids, and kribensis cichlids. Oscar fish are bottom-feeders who primarily eat algae, detritus, and leftover food. In addition to these three species of fish, the most commonly recommended species for a tank is a Corydoras catfish.

These fish are great companions for Oscars because they clean up the bottom of the tank and help remove any excess waste. The list of oscar fish suitable tank mates are below.

Convict Cichlid

They’re quite large – they can grow to about 6 inches. All this means that the convict cichlid is one of the most compatible mates for an Oscar fish. They’ll get on well and avoid confrontations with each other. Since they’ll be able to stay away from each other, they can just defend their own territory

In terms of diet, they prefer small bugs and larvae, but they’ll eat a lot of different things. This means it’s easy to take care of this species. And one more thing: it will eat a variety of different food which you’ll never have to worry about running out of!

Jewel Cichlid

The jewel cichlid originates from Africa – the muddy rivers in central Africa. There are more subspecies of the jewel cichlids – blue jewel, green jewel, jewelfish, and more. They differ in color and appearance. The jewel cichlid comes from the muddied waters of central Africa. There are more than one subspecies of jewel cichlids – blue jewel, green jewel, and jewelfish – all differing in appearance and color.

But above all, this is a very beautiful fish. You can see why it is so popular with tank keepers, but there are some considerations for you if you want to keep them with the Oscar fish as tank mates – don’t keep them in the tank if they are mating or have just one.

Green Terror Cichlid

The green terror cichlid is a fairly aggressive cichlid, so they have to be kept in a community tank. If you have a tank with other fish in it, this breed of ich may chase them away, especially if the stray fish is smaller than them. They can come in green or blue and grow up to 12 inches long.

Female fish are often more aggressive than males, but this would only occur if they have very little space available to them or if they’re threatened. The same goes for smaller fish in a tank who can be easily hunted down by female fish.

Oscar fish are noted for being peaceful, so they should do well in a community tank with other fish of similar disposition. They are omnivores – that means they eat animal and plant foods – but this doesn’t make it hard to take care of them.

Firemouth Cichlid

They are fantastic fish for beginners as well. Oscar fish don’t have many requirements and are perfect for community tanks as tank mates. They can grow up to 7 inches if given enough space and can live for 15+ years.

Jaguar Cichlid

These fish are predatory and will hunt down smaller creatures so it’s good to separate them from your slower-moving, larger fish like Oscars. Breeding time is also when they get more aggressive. To avoid potentially cruel injuries, it might be wise to keep them separated at that time.

Red-Tailed Shark

Red-tailed sharks are found at the bottom of the tank. They’re usually up to six inches long & would be a good choice for tanks larger than 55 gallons. You’ll want to provide these fish with a generous amount of caves and plants.

Bala Shark

They are usually quite active but can be very timid and shy, especially at the beginning. This is natural because it takes time for them to get used to being in a tank or when new fish are introduced.

Clown Loaches

They are known for being one of the larger, more peaceful species of fish. They are also appropriate for tanks that are 75 gallons or more in size. With proper care, these fish can grow to be about 12 inches in length.

Most shrimp species are very docile and make great community tank members.


A pleco can be kept individually in a 30-gallon tank. They are peaceful, so they will make good tank mates for the Oscar.


They are quite good at getting away from larger fish predators, which you might want to take into account if you’re housing them with an Oscar Fish.

Black Ghost Knife Fish

The black ghost knife fish are semi-aggressive fish that would make good tank mates for the Oscar fish. These fish are about 20 inches in length and can live up to 15 years. They need at least 100 gallons for their tank size which needs to be cleaned every other week. If kept with other knife fish they can become aggressive and tend to be shy.

Silver Dollar

Mollies are useful because they can live in tank mates with Oscar fish, which tend to be too aggressive. They’re peaceful and grow to 6 inches in size.

The Oscar fish is usually aggressive towards other fish in the same area, but it won’t ever attack you. As long as you don’t occupy its space, i.e. by sticking your hand in the tank, it will leave you alone

How to Oscar Fish Care

Oscar fish know as intelligent aquarium fish. According to Oscar fish owners, they can recognize their owners. We do not know exactly whether they can face recognize or not, but somehow they know their owners are coming and waggle their fins and head when they come. It is nice to see your fish is happy to see you.

Your Oscar fish do not need hard and laborious caring. They only need clean water, good space, a nutritional diet, and a caring owner. It is not hard to maintain an Oscar tank, but it is challenging to set up one. We hope you got everything you need from this guide. Enjoy your beautiful Oscar tank.

Also, see Guppy Care Guide

Other types of oscar fish

  • tiger oscar
  • albino oscar fish

Oscar only tank

If you are considering adding an Oscar Fish to your community tank, do so in advance. The best time to add them is far before adding other fish to the tank.

One way to do this without any fuss is to set up an Oscar-only tank. Experienced aquarists can choose from a variety of other cichlids that will complement and interact well with the Oscar. The preparation for this specific make-your-own aquarium is a little bit more complicated, but the results are well worth it. You can populate your tank with extraordinary fish that do well in different conditions.

Will Oscar Fish Jump Out of Tank?

If your Oscar Fish spots something outside the tank that looks like food, it will jump out to retrieve the object. In the wild, Oscar Fish will get very excited when they come across an insect and want to reach it quickly and eat it.

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About Dr.Chamika

Hello, I'm Dr. Chamika. I am a Researcher in Water quality, Aquatic organisms, and Environmental chemistry. I am a passionate fish keeper, with10 years of experience. My mission is to help other aquarists experience the joy of fish keeping.