Oscar Fish

Common Name/Origin:Oscar – Astronotus ocellatus

Lutino tiger oscarThe Oscar fish is originally from South America. They are found in the Amazon River Region especially in the Brazil region. Oscar’s thrive in the flooded river plains off of the Amazon. They can also be found in lakes and ponds throughout this region.

Today, in the United States, Oscars are being caught in lakes, streams, canals, and ponds in Florida and several other Southeastern States. This is due to tropical fish keepers releasing their wet pet into the wild when they outgrow their aquarium tank. In Florida, it is against the law to introduce this non-native species into the wild.

Oscar Temperament

Although Oscars are considered to be aggressive, they are not “super” aggressive. What I mean is that they are more territorial and will not necessarily bully every fish in the tank just because they can. Most Oscars will allow for you to keep tank mates with them. Please remember as with any cichlid, every Oscar is different and some may be more aggressive than others.

Oscar Size

Oscar cichlids grow up to 16 inches in the wild but most likely will only reach between 10-14 inches in the home aquarium tank. Not only is the Oscar fish a very long fish, it is a thick specimen also. This fish will grow to be big! Many grow over 2 lbs in weight.

Oscar Lifespan

The Oscar cichlid can live up to 15 years of age. Most Oscars in our home aquariums if kept healthy will average 10-12 years of age.


Oscar Color Variations

The Oscar fish comes in a variety of colors. These include red, lemon, albino, tiger, red tiger, and albino tiger aka Lution cross.

Oscar Water

pH 6.8-8.0

Soft Water

Temperature: 76-82 °F

Sexing Oscars

There are no obvious distinctions between male and female Oscars. This means that the Oscar is monomorphic. When there is no visible distinction between the sexes, you must wait to see the fish spawn to truly distinguish the sexes. Females will drop their tube, which is more oval in shape to lay her eggs. Males will fertilize the eggs and their reproductive organ is more pointed.

Oscar Tanks

The suggested minimum tank size for keeping one single Oscar fish is a 55-gallon tank. Although, a 70-gallon or larger will be much better for you and your Oscar fish. Remember that a 55-gallon tank is just over 12 inches wide, and your Oscar fish will be close to that in length when full grown. I recommend you purchase the largest tank you can afford when you plan on purchasing an Oscar.

The aquarium tank should have a tight fitting lid or canopy on it to prevent your Oscar from jumping out and landing on the floor. Oscars do like to come to the top of the water and some leap out of the water trying to get food. The last thing you want is your Oscar found on the floor when you get home from work.

Oscars love to dig. You need to keep this in mind when decorating your tank. You may choose to use gravel or sand as a substrate. I will tell you that Oscars poop a lot and if you use sand, you will see this on your substrate often. Now, if you use gravel, you will have to vacuum the gravel often to ensure that you are removing the waste from the water.

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Do not purchase live plants. Oscars love to tear them up and play with them. They will even shred your fake plastic plants. You can try them, but do not be surprised if you end up with no plants live or artificial in your aquarium tank.

Oscars will enjoy a piece of driftwood or cave that they can retreat to when needed. Oscars will choose a portion of their tank as a safe haven so ensure you have something in there even if it is empty clay flowerpot.

Oscar Food

Oscars are carnivores. This means that they eat meat.

Important note… Oscars will eat anything that will fit in their mouth.

Oscars need a well balanced diet. I prefer to stick to one type of pellet food for the staple diet and supplement with treats and other forms of food.

So what are the other treats and supplemental foods?

In nature, Oscars eat other fish and insects. They may even eat fruits and vegetables that are washed into the waterways. So you can feed your Oscar any of the following: insects, worms, frozen prepared foods, pellet, and freeze dried. If you feed insects, please ensure that no pesticides have been used nearby.

As your Oscar grows, you’ll want to find larger treats for him to eat. So instead of feeding brine shrimp, or mysis, try feeding him raw shrimp. I always peel mine and rinse it off before feeding.

I would stay away from feeder fish. These are fish that your local fish store will try to sell you so you can feed your Oscar “live fish.” Do not fall into this trap. Feeder fish often carry diseases and if your Oscar eats these fish, he too may become ill. There is nothing nutritional about feeder fish purchased in a fish store. If you raise your own feeder fish, and know for sure they clean and disease free, go for it!

The key to a healthy Astronotus ocellatus is a good varied diet. Mix it up!

Oscars are known as “water pigs”. Oscars are very messy eaters. It is completely natural for your Oscar fish to grab the food, take in their mouth, chew the food, and spit it back out. This process is repeated several times and then eventually they will swallow the food. This process is very messy so having the best filtration system on your aquarium tank is vital.

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Oscar Tank Mates

The Oscar cichlid may have tank mates but there is one key thing to remember. If the fish can fit into the Oscar’s mouth, they are a potential meal.

Oscar fish will live with just about any other cichlid that is similar in size to them. The key to finding favorable tank mates for Oscars is finding one that is not too aggressive or too passive.

The best tankmates that I have had experience with are Silver dollars. These fish act as dithers. This simply means that the Oscar will see these active swimming fish out and about in the tank and feel secure enough to stay out in the open also. Silver dollars are quick, grow large, and do a great job at cleaning up after the messy eating Oscar.


Tiger Oscar FishAnother excellent tankmate is the Severum Cichlid. This fish can hold it’s own, grows large enough not to be eaten, and has a great personality also.


I would stay away from small to medium catfish. Oscars are known for trying to swallow catfish and the spines on the catfish typically get caught in the Oscar’s mouth. This can lead to the death of your Oscar.

Keeping multiple Oscars together can be done successfully. Remember that each cichlid is different, so keeping multiple Oscars together may or may not work for you.

When adding tank mates, ensure that your tank is large enough for multiple fish. Do not add anything to an Oscar tank less than 70-gallons. Your Oscar will just bully it and the bio-load will be too much for a tank that size.

*Potential tank mates: Jack Dempsey, Green Terror, Plecos, Firemouths, Severums, Silver Dollar.

Oscar Features

The best feature of the Oscar Fish is it’s personality. The Oscar is often referred to as the water-dog. If you are looking for a true wet pet, this species is the one.

The Oscar loves attention, and will perform antics to attract that attention to itself. Oscars have been known to spit gravel, spit water out of the tank, knock the hood open, and swim frantically in the tank for your attention.

Oscars can be trained to eat food out of your hand, be petted, and play with toys. Yes, I said toys. Many people give their Oscar ping-pong balls. It is hilarious to watch the Oscar play with a ball in the water. Many Oscars love to be rubbed and petted like a dog. Please make sure you hand is wet and do not do this too often because you may damage the natural slime coat unintentionally.

Please be aware that Oscar cichlids are somewhat destructive to the tank and equipment. Many Oscar keepers report that their heaters and filter intake tubes have been broken or damaged. Be sure to purchase a heater that is “shatter-proof” to ensure the Oscar’s and your safety.

Breeding Oscar Fish

Oscar Fish SpawningSince Oscar fish look exactly the same between males and females, it is very hard to successfully go out and purchase a “Pair” of Oscars. Many Oscar cichlid keepers prefer to purchase several (six is a good number) Oscars while they are young and let them pair off naturally.

If you choose this process of successfully getting a mated pair, this means you will have four Oscars to find a new home for. Ensure that you can do this before purchasing your Oscars. Many fish stores will not have room for four large Oscars. Please do not release them into your local waters either. This is not good for them or our natural environment.

Just because you have two Oscars that get along well, and show spawning behaviors, doesn’t mean that they will always get along. During spawning, your Oscars may chase, bite, circle one another, and flat out fight. This is natural, just monitor to ensure it is spawning activity and not two of the same sex going after each other.

When your Oscars are ready to spawn, they will lay their eggs on a flat rock or they will clean the substrate to the bare glass. Oscars lay a lot of eggs. They can lay close to 1,000 eggs per spawn. The male will follow the female as she lays the eggs and he will fertilize them as he swims.

After 3 days, most of the eggs should hatch. They will have a yolk sac attached to them for about 5-7 days. To successfully raise the fry, you will need to feed artemia, crushed flakes or baby brine shrimp.

The parents will guard the eggs and young fry from everything in the tank including your hands. Be aware that they may come at you and bite you if you try to remove the fry or eggs. To raise the fry with the most success, removing them to their own tank is suggested. Some parents will eventually eat their young, while others do very well raising the young.

Overview – Oscar Fish Care

Overall, Oscar fish make excellent wet pets. Please be aware that the Oscar cichlid grows really fast. That little 3

-inch fish you purchased will be around 9-10 inches within 12 months. Please make sure you have the space for an Oscar fish when you purchase it.

Do not buy this fish and put it in a 10-gallon aquarium hoping to purchase a larger tank later.

Oscar Fish Fun Fact

One of the Oscar’s personality traits is that it will actually sulk when it gets upset. If you change up the decorations, do a large water change, or move tankmates, the Oscar may actually pout like a small child.

This is perfectly normal. The Oscar fish may hide or lay on the bottom for several days. Your Oscar may not eat during this time. After 3-4 days on average, the Oscar will begin moving around the tank again like normal.

*Please note that the Oscar Fish is a cichlid and has it’s own personality. You may find tank mates that work really well, while others listed to not work. Your success with tank mates will depend on the individual Oscar cichlid you own.

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