The Oscar Fish Care Guide

Oscar fish, also known as Astronotus ocellatus or tiger fish, belongs to the group of cichlids. Oscar fish is native to the South American region and is a large multicolored creature. It is considered to be very intelligent and showcases very interesting behavior. They have a brilliant memory and are among a few of the aquamarine pets that can be trained to do tricks. There are many different types of Oscars, but the most commonly found are black with bright red scales. Although these fish do not really fuss when it comes to food, it’s very important to provide them with a healthy, clean environment.

Oscar Fish Care and Tank Setup (Video)

The major types of Oscar fish

Following are the 3 major types of Oscar fish.
  • Tiger Fish which are thought to be the original Oscar fish. They have chocolate brown or gray base with orange or crimson markings. These fish are pure breeds and no major abnormalities are found in them.
  • Red Oscar can be found in various shades of red. The shades include bright red, rusty orange, and deep red etc. They do not have any markings or patchy spots like the tiger fish.
  • Albino Oscars are white in color, as the name clearly suggests. They may look different than all the other types but they have the same behavior and breeding pattern. This kind of Oscar possesses shiny white scales that give it a velvety look.
This list is not exhaustive at all. In fact, Oscar fish have dozens of different breeds. You can watch this video for details on more types.

Setting up the tank

As mentioned earlier, Oscars are not small fish so they require a lot of living space.If you want that your Oscar reaches its full potential in terms of size, then you need to pick out a fish tank that holds at least 100 gallons of water.Anything that is less than 55 gallons per fish will be troublesome and cause unnecessary stress to the fish. If you are new to this, then follow the guide given below:
  • 1 Oscar – 75 gallons
  • 2 Oscars – 125 gallons
  • 3 Oscars – 150 to 200 gallons

Number of fish

Oscars are very social and they enjoy being in pairs and groups.If you have enough space, then keep 2 of them. In case you can’t have enough of these fish and want more, then I’d say that 5 is a rather manageable number.Do keep in mind that keeping 3 is not a very good idea as two of the fish will bond and the other one would feel left out and just be the “third-wheel”.

Temperature and pH level

The temperature of the aquarium for Oscars should be kept around 74 degrees Fahrenheit to 81 degrees Fahrenheit. Do make sure to keep the temperature constant as fluctuating may affect the health of the fish due to their sensitive nature.Oscars can tolerate a wide range of conditions, so tap water is fine. The pH of the water in the fish tank should be around 7 and the relative hardness should be between 5 to 20 dH.Oscars can easily adapt to both softer and harder conditions.

Filtration system for Oscars

Oscar fish are quite sensitive when it comes to ammonia and water changes.In order to keep the fish healthy, you need to invest in a very high-quality filtration system. On the other hand, the Oscars are very messy fish and have a large waste output.So, in order to keep this problem at bay, you need an amazing water filter that concentrates on biofiltration.A hang-on-back filter or even a canister filter as a backup will probably be enough to take care of things. It is important that the water filtration system you choose has the capacity of turning over the entire volume of the water in the tank about four times over.

Hoods are a must

Oscars are very playful creatures and are known to leap to their deaths if their aquarium does not have proper tank conditions. So, you need to make sure you purchase a tank hood with flaps that latch onto the tank and hold them down.An Oscar fish can actually prop open the hood by banging on it, so the flaps are important.Another tip for preventing the Oscar fish from jumping is to keep the underside of the tank hood and lids very clean. In the wild, many insects land on the surface of the water and the fish have to jump in order to eat them.In captivity, the underside of the lid might drip moisture or there could be particles of leftover food stuck there. This could fool the Oscar fish causing them to jump and bang on the tank hood. Hence, it is vital for you to keep the hood squeaky-clean at all times.

Lighting Essentials

Oscar fish are not really bothered by lighting, so they do not need any kind of special care in this regard.Keeping them simply in a room that gets standard amount of daylight is fine. If you want to add lights, then do not keep the light bulb on for more than 12 hours a day as too much light may cause the fish to get unnecessarily agitated.Before adding any lights, make sure you test them on the Oscars. If the fish shy away from it, then you should consider dimming the light bulb or even removing it completely.If you do not know how to dim a light bulb, then you have come to the right place. It’s relatively easy. Just poke some holes in a piece of tin foil and wrap that around the bulb.Lesser the holes, dimmer the light bulb will be. More holes, on the other hand, would allow more light to pass through.

Plants, Gravel, and accessories

The most important part of keeping accessories in the fish tank is to keep them rooted as fish can easily lift out the plants or even move the rocks present at the bottom.So, it is best to keep fake plants and sturdy decoration such as stone caves and PVC pipes. Protecting the fish is very important as well, so avoid adding anything to your tank that has rough textures or sharp edges.

Proper nutrition

Oscars are carnivores, so the best diet for them is a meaty one.Take processed or dried food and pellets which are specifically made for the Oscar fish and then freeze them. Add feeder worms, insects, shrimp and fish to your fish’s diet in order to provide it with the nutrition that it needs to grow big and strong.Oscar’s diet should only consist of lean foods. So, avoid feeding your Oscar fish beef and poultry heart.

How to feed Oscar fish?

  • Begin by feeding the baby fish 3 to 4 pellets. Drop them in and then wait for your Oscar to finish eating them. After that, add some more
  • Do this for about three minutes and then stop
  • Make sure that your fish have eaten all of the food in its vicinity and then remove any leftover food particles
  • Repeat this process twice or thrice a day
Once the Oscar fish has grown over 5 inches in length, you should change its feeding patterns. After that, you should feed them only twice a day with a diet that consists of larger supplements that include living animals such as grasshoppers or mealworms.

Breeding the Oscar fish

Breeding Oscars is a tad bit harder than breeding other freshwater fish varieties and the most difficult part is pairing two Oscars.It is actually quite a thrill when Oscar fish breed for the first time. If you have been keeping Oscars for a long time, then it is very likely that you raised a breeding pair.If you do not have an adult pair, then you can get one from your local pet store.

How to identify a breeding pair?

Oscar fish become sexually mature when they reach about 14 months of age and their size is around 6 to 20 inches. The size and age cannot be counted upon for giving accurate results as in many cases, Oscars refuse to breed until they are about 3 years old.The safest bet, in this case, is to examine the breeding tubes. These can be found on the under-side of your fish and are great indicators of sex. The breeding tube of the male Oscar fish have about third the mass of the female’s tube. They are thin, curved, and their length is far greater than its width.The breeding tubes of the female, on the other hand, are flat at the tip, short, stubby and their length and width are proportional. The breeding tubes are only visible before spawning.

Initiating the breeding process

The female Oscars begin breeding when they sense that the rainy season is about to begin.This is only the case in the wild as at home aquariums, the water parameters tend to be constant throughout the year and it is hard for the fish to tell if it’s the breeding season.In order to combat this problem, you need to stimulate a rainy season environment. You should begin the process by carrying out a 20 percent water change every few days.Another vital aspect of the rainy season is the decrease in the temperature of the water. You should lower the temperature of the fish tank by a couple of degrees.In order to portray the essence of the rainy season, sprinkle water on the top of the fish tank for about 10 minutes a few times a day. You can also install a spray bar just above the surface of the water. Most of the Canister fillers already have built-in spray bars.

The breeding begins

When the Oscar fish are ready to breed, there will be fin-spreading, side-by-side wagging, gill flaring, vibrating, tail slapping, vibrating, and jaw shaking and locking.The Oscar fish will also clear the gravel from a flat rock and then they will begin to scrub the surface. This rock cleaning might go on for days or even a few weeks. At this moment, Oscar fish are preparing a clean and safe place to lay eggs.The process of spawning begins when the female Oscar fish’s ovipositor (structure used to deposit eggs) descends and when the male Oscar fish’s extends shortly thereafter. Spawning is imminent and may begin in 48 hours or so.The colors of both the parents fish intensify, their tubes extend down and vigorous scrubbing of the flat rock and false passes by the female over the rock are definite signs of spawning. After the female conducts a few tries, the eggs are finally laid and then the male makes a pass over the eggs.The eggs are opaque, white and about a millimeter in diameter. They are very similar to dead eggs of other fish.The process of spawning may take up to three hours and it results in a 7 inch or larger patch of evenly spaced rows of eggs. Small fish may produce about 400 to 500 eggs on their first spawning and the larger fish normally produce about 2000 to 3000 eggs.

Post-spawning stage

The Oscar fish fry will most probably hatch within 72 hours of being laid. Most of the eggs just disappear; this is because the eggs that are not fertilized are consumed by the parent Oscar fish.This is not always the only reason for consumption. If the Oscar parent pair gets stressed or upset in any way, they end up consuming the eggs. Mostly it takes the parents a few tries before getting the spawning process right.The unfertilized eggs will be white in color while the fertilized ones will showcase a tan or light brown shade.Some of the unfertilized eggs might develop a cotton wool type fungus and it might even spread to the fertilized eggs. You can add Methylene blue to get rid of the fungus but this might cause your tank to pollute so it is best to not try this at such a sensitive time.Under normal circumstances, the parent Oscar pair will pick up on the fungus and consume the affected portion of the stock.

Artificial incubation

Many breeders have to, unfortunately, experience months or even a year of false spawning. The only solution to this dilemma is patience or artificial incubation.

Transferring the Fry

You should decide before the eggs hatch if you want to keep the fry in the same tank as their parents who might consume them or transfer them to another tank for rearing.If you choose the latter you might need more space but this will increase the fry’s chances of survival.Be sure to use the same water as that of the adult tank if you want to transfer the eggs to a new one. The Oscar parent pair will defend their eggs when you will try to remove them. Place the eggs into the other tank and be careful not to expose them to the air. Leave them there until they hatch.

Choosing tank mates for the Oscar Fish

It is very important for you to choose a fish that can live in harmony with your Oscar fish. Oscars are carnivorous so you cannot put small fish with them as they will most probably eat them. Nothing less than about 5 inches should be added to a tank occupied by an adult Oscar fish.It is very vital that you add the right kind of fish to the tank. For example, the Angel fish is not the best choice because they have long flowing fins and they are rather delicate; plus these fish prefer taller tanks.Fish that are bottom-dwelling are an excellent choice as Oscar tankmates as they tend to stick to the bottom and do not interfere with Oscar fish activities that spend most of their time at the mid or top layers of the water.Other small species of cichlids are also a good choice; even though they are small but they can put up a fight and protect themselves.

Avoid the catfish

Catfish also belong to the same South American region as the Oscar fish and they tend to be good tank mates. But the problem arises when your Oscar fish tries to eat it.You know how the old saying goes, “If a fish can fit into the mouth of another fish; it will!”The Oscar fish takes the catfish in its mouth and then tries to swallow it. Soon it realizes that it cannot and then tries to expel it. Catfish have spikes that dig into the throat and mouth of the Oscar fish and so they are unable to spit the catfish out. The Oscars eventually die.

A few suitable tankmates

Following are a few great tankmates for Oscar fish.Silver Dollars: These are very social fish and feel more comfortable being in larger numbers and are very placid in the tank.Black Convict Cichlids: These fish are not the largest ones out there but they make excellent tank mates for your Oscar fish. Try adding a couple of rocks or pieces of wood as Black Convicts tend to love the cover.Blue Acara:These fish are small but very aggressive; they can easily protect themselves from the Oscar fish. The best thing is to purchase them as adults because they are poor at competing for food when they are small especially if there is more than one Oscar fish.Jurupari Earth Eaters: These types of fish love being in groups and hate being on their own. They can easily compete for food and can feed on sinking food and bloodworms. Hence, they can serve as excellent tank mates for your Oscar fish.Severum: These fish make good tank mates for the Oscar fish as they have the ability to stand up for themselves and can easily compete for food.Jade Eyed Cichlid: This is one kind of cichlids that works great with Oscars and they are from the Central American region.Black Banded Leporinus: This type of fish is very timid, enjoys its own company and is not very aggressive. Sometimes, the fish may end up nipping at the fins of other fish but that’s perfectly normal and harmless. They are rather skittish so any sudden movement in front of the tank might frighten them. The Blank Banded Leporinus love eating peas.Fire Mouth: These are very small cichlids that do not grow beyond 8 inches. This is another kind of fish that can stand up for itself against the Oscar fish in the tank.Plescostomus: This type of bottom-dwelling fish is very popular due to its ability to clean the algae at the bottom of the tank. There are some species of Pleco that can get quite large and exceed even 18 inches in length. They need at least 100 gallons to survive, so do yourself a favor and do not buy this fish if you do not have enough space.

Common diseases in Oscar Fish

Oscar fish are susceptible to a lot of diseases in aquariums. In order to better care for them, you need to be able to diagnose them in an emergency situation and take necessary measures for their cure.

Hole in the head

Oscar fish is a very healthy species and the chances of them getting sick are quite slim. But it is not uncommon for them to contract certain diseases if you do not take proper care of them.The most common disease they can get is the hole in the head disease. The name itself is self-explanatory. In this disease, holes develop across the fish’s head and body.This disease is very easy to treat but the sooner you identify it, the easier it is to cure it. The hole in the head disease is mainly caused by nutritional deficiencies in the Oscar fish’s diet.Some of the symptoms of this disease include:
  • Loss of appetite
  • Large holes and sores
  • White sores around the eyes and on top of the head
  • Mucous Trailing from the holes


This disease can prove to be fatal if it is left untreated and can be easily treated by using Flagyl. You can add the drug to the fish tank and let the fish bathe in it or you can medically administer the drug by adding it to the food flake of your Oscar fish.Bear in mind to never self-medicate your fish. Before you use any medication, consult a professional on which medicine to use and how to administer it.

Fin and Tail Rot

This disease is caused by a bacterial infection. Some of the culprit bacteria include Columnarae, Aeromonas spp, Flexibacter spp, and Flavobacterium columnarae etc.Factors such as overcrowding, low oxygen levels, and poor water quality can cause this.Some symptoms of this disease are:
  • Loss of appetite
  • Spending more time at the surface
  • Parts of the fin might tear and fall off
  • Bloody, Tattered or blackened fins
  • Milky appearance of the body or fins
  • Lethargy or listlessness


The fish that are affected may require surgery in order to remove the infected tissue. The fins do grow back themselves, though.Antibiotics that should be given to the sick fish include Tetracycline, Chloramphenicol, and Oxytetracycline etc. Again; do not administer any medications without a professional’s advice.If you are going to feed your Oscar fish live feeder fish than it’s best that you make sure that you quarantine them before adding them to your main tank. The most common cause of this disease in this kind of tropical fish is the introduction of foreign bacteria from things carelessly put into the tank by the owners.

What to look for while buying an Oscar fish

  • The fish should seem active and lively
  • Select fish that reside in clean well-kept tanks
  • The fins should be intact and no spots or holes on their heads or fins should be visible

Tips to prevent diseases in Oscar fish

Most of the Oscar fish diseases are born from the same source which is mostly linked to be the water of the aquarium. You can follow the steps below to protect the health of your fish
  • Make sure that the level of ammonia and nitrates in the water are adequate
  • Test the Water frequently
  • Add a thermometer to your tank and make sure that optimum temperature levels are observed at all times
  • After you buy a new fish, quarantine it for about four to six weeks as the new fish carrying parasite might infect your other fish
  • Follow the manufacture directions and change filter pads and materials frequently
  • Do not overcrowd the fish and always provide it with ample space
  • Never buy a fish that had been kept in a dirty cloudy tank or a fish that is visibly sick
  • Do not leave your fish untreated, treat them as soon as you can and also separate the sick fish from the healthy fish
  • Feed you Oscar fish a diet that keeps all its nutritional needs in check; meat derivatives are the best options
  • Maintain the pH levels of the water, tap water pH is fine
  • Clean the aquarium frequently but do not overdo it as Oscar fish are very sensitive to change
  • Use a high-quality filtration system because Oscar fish are very messy and it is hard to keep their environment clean
  • Research on the best tankmates for your fish and do not add just any fish

Related questions

Where can Oscar fish be found in the wild? The oscar fish is native to South American countries that include Brazil, Colombia, Peru, and Paraguay etc.What is the lifespan of the Oscar fish? Oscar fish can live up to 10 to 15 years if they are provided with the proper living conditions.Why does my Oscar fish yawn? There are three theories regarding fish yawning; the most probable of which is that they might do this to remove irritants from their body into the water or even due to high nitrate concentrations in the aquarium.Related

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