Oscar Fish – A Complete Guide (Care, Diet, Facts)

Oscar fish have garnered quite the reputation for themselves in the fishkeeping world. Their beauty and striking colors dramatically contrast with their reputation for aggression. However, if treated correctly, Oscar fish can be a striking addition to a home aquarium.


Oscar Fish Overview

Oscar fish are members of the Cichlidae family and are native to South America. The term “Oscar” actually refers to a fairly broad family of freshwater fish within the Oscar family. These include the Tiger Oscar, Red Oscar, and Albino Oscar, among many other varieties. Of these varieties, the Tiger Oscar is widely regarded as being the original Oscar fish from which other varieties were bred. Different variations of Oscar fish can feature drastically different patterns and colors. However, their behavior and needs vary only marginally between varieties. For this reason, an overarching guide such as this applies to all varieties of Oscar fish.

Oscars are widely regarded as being intelligent fish. They are said to have a sense of loyalty to their owner and have even drawn comparisons to a domestic dog. In fact, Oscars can even learn simple tricks that they will perform for their owner (in exchange for a snack, of course). These characteristics, in addition to their striking colors, make them primary candidates for an in-home aquarium. It must be noted, however, that these fish have an average in-captivity lifespan of 10-12 years. Thus, a potential owner must be prepared for a long-term commitment to their Oscar fish.

These fish are admittedly not the easiest to care for. Their tankmates must be carefully selected as a result of their inherent aggression. In addition, these fish in captivity can grow to be over a foot long, so they require a great deal of space. However, with this guide handy, caring for an Oscar can be made simple and enjoyable for many years.

Tank Requirements

Prior to purchasing an Oscar fish, it’s important to review the tank specifications to ensure that they are appropriate to house an Oscar fish. The common standard is 40 gallons per Oscar fish, plus additional volume for any other fish in the tank. This value is given to reduce stress on the fish that could be caused by a small environment. With Oscar fish especially, maintaining this value is paramount to keeping aggression levels low.

In addition, a hood for the tank is recommended. Oscar fish, with their high energy and aggression, are capable of escaping the confines of their tank with a strong leap. This hood should have a latch or weight on top to ensure the fish can’t push it aside. It may seem like overkill, but these fish are extremely capable of fairly complex escape maneuvers.

As a result of their South American roots, Oscar fish are accustomed to fairly warm water temperatures. This means that a tank housing Oscar fish will need a tank heater. The established temperature for these fish ranges from 74 to 81 degrees Fahrenheit. Any temperature within this range is acceptable, but it important to not allow the temperature to drastically fluctuate. This can lead to serious health problems for the fish down the line.

The pH of the water is also an important factor to consider when setting up a tank for Oscar fish. The ideal pH has been established as roughly 7.2. pH should never be set at less than 6 or more than 8 and shouldn’t dramatically fluctuate.

Oscars are admittedly not “clean” fish. They create a lot of waste and can often be destructive towards decorations and equipment in their tank.

To counter the amount of waste produced by these fish, it’s important to have a high-functioning water filtration system in place. Both a canister filter and a backup hang on back filter is recommended. The filtration system should be capable of filtering the entirety of the water in the tank at least 4 times per day. This should also be paired with a weekly 10-15% water change, performed manually. This will be discussed in depth later in the guide.

As mentioned, Oscar fish are typically abrasive towards decorations and equipment in the tank. This means that all decorations and equipment will have to be safeguarded against daily abuse. For example, a light structure can easily be moved by these fish and can result in damage to the glass of the tank. It can also result in damaged equipment that can be costly to replace.

This doesn’t mean than an Oscar’s tank should be without decoration. In fact, they should have an abundance of decorations and structures to interact with. This will keep them calm and reduce aggression levels. These fish also feel vastly more secure when they have hiding places readily accessible to them. However, only sturdy structures and plants should be used as decorations in the tank.

Finally, the substrate for the tank must be considered. Many Oscar owners opt for a bare-bottom tank for ease of cleaning. This is, however, not similar to the Oscar’s natural habitat. It is recommended instead to have a gravel substrate that won’t get sucked into the tank’s filtration system. Feel free to experiment with different substrates to find the correct ratio of ease of cleaning to maintaining a natural habitat-esque feel.

Feeding Requirements

Because of Oscar fish’s inherent sensitivity, their diet is critical to keeping them healthy and happy. As a result, Oscar fish should always be fed food that is healthy for them.

Of course, it’s not always easy to deduce what foods are healthy or unhealthy for a fish. The consensus for Oscar fish in particular is a mixture between processed Cichlid pellets and live, natural food.

The Cichlid pellets provide vitamins and minerals necessary for Oscars to thrive in captivity. These pellets should only be purchased from reputable vendors to ensure that they aren’t packed with fillers and unhealthy ingredients. It’s important to evaluate all of the ingredients going into a pellet prior to purchase and feeding. It is also important to choose the correct size of pellet to feed to an Oscar fish. Oscars are excited to eat, and they will often try to eat these pellets in a single bite. If a pellet is too big, this can result in difficulty swallowing. It is recommended to start with a small pellet size and increase the size as the fish continues to grow.

These pellets should be paired with natural live foods. This can include land insects such as crickets, locusts, grasshoppers, mealworms and garden worms. They can also be fed various seafood, such as cockles, mussels, prawns, shrimp, tuna, salmon and squid. It is generally unadvised to feed Oscars with goldfish. These fish are extremely disease-prone and can pass illnesses onto the Oscar fish.

In addition to live food, Oscars can also eat fruit and nuts. These are consumed by Oscars on a seasonal basis in the wild. Thus, it is recommended to only feed Oscars fruits and nuts that align with their seasonal availability in South America.

The frequency by which Oscar fish are fed is also an important factor in keeping Oscar fish healthy. This schedule is largely based on the stage of the Oscar fish’s life. Young Oscars, generally less than 3 inches in length, should be fed twice per day. This is to ensure that they are getting the necessary nutrients to grow healthily and not lack for vitamins and minerals necessary for growth.  They should only be fed a bit at a time, as they will attempt to immediately consume all the food that is placed in the tank at a single time.

When the fish are between 3 and 6 inches, many owners opt for a staggered feeding schedule. This often involves feeding twice on one day, and then feeding once on the subsequent day. This provides enough nutrients for growth but doesn’t result in overfeeding.

When the fish are longer than 6 inches it is recommended to feed them only once per day.

Tank Maintenance & Care

As mentioned earlier, regular tank maintenance is critical to the health of Oscar fish.

One of the best things that can be done to ensure clean water for an Oscar is to perform a 10-15% weekly water change. This involves taking 10-15% of the water out of the tank and replacing it with new, dechlorinated water. This allows for contaminants to be removed that may have been missed by the filter. During this change, it is acceptable to leave the decorations in the tank. However, it would be wise to take this opportunity to use a siphon to clean the substrate and decorations from waste that may have collected over time.

It is also important to continually check water pH to ensure that it is within the aforementioned range of 6-8 pH. This can be done with a general water pH test kit widely available at pet stores.

Uneaten food should also be regularly cleaned from the tank. Excess uneaten food in the tank can dirty the water and result in diseases. In addition, the fish’s feeding schedule may need to be reevaluated if uneaten food becomes a regular occurrence.

Finally, it important to do an occasional deep clean of the tank. This includes a thorough cleaning of all tank decorations and a substrate change. This may seem like overkill, but it can be performed sparingly and provides a drastic benefit to the Oscar’s quality of life. The result is a happier Oscar who is more interactive and playful.

Tank Mates

Because Oscars are a handful to care for in-and-of themselves, many owners elect to have Oscars in their own tank, and away from other fish. Many, however, opt to integrate other fish into their Oscar fish habitat.

Choosing a tank mates for Oscar fish is no easy task. Because of their strength and aggression, they often feud with other fish in the tank. This can lead to drastically elevated stress levels and potentially even death. As a result, care must be taken in choosing appropriate tank mates.

The primary tank mates for Oscar fish are other fish in the Cichlid family. These fish are able to avoid conflict and hold their own against Oscar fish, and thus can make for great tank mates. These fish include the Severum Cichlid, Green Terror Cichlid, Black Convict Cichlid, Chocolate Cichlid, Jack Dempsey Cichlid, and the Firemouth Cichlid, among others. These are all vibrant-colored fish that would make great additions to an Oscar tank.

In addition to Cichlids, there are many other fish that are compatible with Oscars, such as Silver Dollars and Bichir fish.

Essentially, a tank mate for an Oscar would have to be a species with the ability to protect itself and fend off attacks from Oscar fish.

Diseases and Treatments

Unfortunately, because of Oscar fish’s fairly sensitive nature, they are susceptible to many diseases that they may encounter in captivity.

One of the most prominent diseases affecting Oscar fish is called hole in the head disease. This disease is immediately recognizable, as it creates sizable lesions in the head of the Oscar. This disease has no definitively established single cause. Rather, it’s speculated that there are multiple causes for this disease.

One of the primary causes has been traced to the parasite Hexamita. This parasite infects the Oscar fish and can ultimately cause hole in the head disease and potentially even death. This parasite is present in many fish who don’t display any outward symptoms of the parasite. However, when the immune system is compromised in some way, this parasite can start taking its toll.

Malnutrition and poor water quality have also showed signs of contributing to hole in the head disease. Not only can it exacerbate the effects of Hexamita and develop into hole in the head disease, but there has been data that these conditions can cause the disease without the presence of the Hexamita parasite.

Luckily, this disease is treatable. A medicine called Metronidazole has been proven to cure Oscars of this disease. This medicine can be put on food and fed to the Oscar. Once cured, it is important to clean the entire tank and replace the water to ensure that remnants of the disease aren’t still present in the environment. Specifications regarding dosage are typically available on the medication package.

Another common disease facing Oscars is Ich, or the White Spot Disease. This disease, like Hole in the Head, is aptly characterized by its name. Fish with this disease can be identified by the presence of white spots covering the body. This disease affects many breeds of fish, and can unfortunately become deadly.

There are a few methods that have been suggested for treating this disease. The most common is a salt treatment. This involves putting 4-5 tablespoons of salt for every 5 gallons of water in the tank. This should be maintained for 10 days. This has been proven as a fairly effective standalone treatment for Ich.

There is also the heat treatment method for treating Ich. This treatment involves slowly raising the water temperature to 86 degrees. This is said to destroy the organism that kills Ich. If using this method, it is important to constantly agitate the surface of the water in order to introduce more oxygen to the tank. This is because warmer water holds less oxygen.

These methods can be combined for the most effective treatment. However, if combined, it is recommended to lessen the salt treatment to 2-3 tablespoons per 5 gallons rather than the standalone 4-5 tablespoons.

There are many other diseases that can be encountered by Oscars, however the pair described above are the most common.

Breeding Oscar Fish

Oscar fish are not easy to breed in a home aquarium. In fact, breeding Oscars anywhere but their natural habitat will prove to be a challenge. However, this task is not impossible.

The first challenge in the breeding process comes from Oscar fish’s selective breeding personality. These fish won’t simply breed with any opposite-sexed Oscar; they are instead very particular about their mate. In addition, this process cannot even begin until the Oscar fish has matured. This typically occurs when an Oscar turns 1 or 2 years old.

Oscars typically mare during the rainy season. Ass a result, owners should replicate rainy season conditions in the tank of a potential Oscar couple. This includes lowing water temperature and splashing water drops on the tank’s surface.

Once the Oscars initiate the mating process, it’s advised to move them into a separate tank, away from other fish. This is because the mating routine tends to make Oscars even more aggressive than usual.

Once the Oscars are born, they should remain in a separate tank. This will ensure their safety from other fish. They should also be fed multiple times a day to ensure healthy growth.


Oscar fish, when treated correctly, can be beautiful additions to a home aquarium. They are highly interactive, intelligent, and eye catching. However, with these attributes comes sensitivity and aggression that must be constantly monitored.  It is important to thoroughly evaluate the characteristics of potential tank mates to ensure a proper fit with the Oscar. In addition, it is crucial to regularly inspect the Oscar for indications of a potentially life-threatening illness.

In short, Oscars will provide years and years of fun and interactivity. Individuals who are committed to a long-term fish and relatively vast equipment requirements should look to an Oscar for their next tank attrition.

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