Oscar Fish - Astronotus ocellatus

Updated May 13, 2020
Author: Mike - FishLore Admin
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This fish is also known as the Red, Albino and Tiger Oscar. Originating in the waters of the Amazon, this cichlid is another extremely popular fish. Their popularity stems from their personality, which has been compared to that of a puppy. Many keepers experience begging around meal times or the seemingly playful greetings they receive from their fish when they get home.

Astronotus ocellatus Astronotus ocellatus


There are a few color varieties of the Oscar including albino, olive-green, brown and dark gray. They can get quite large, usually 12-14 inches and should be kept in a 75 gallon or larger aquarium. It is also known for being one of the more messy fish to keep. Try to get the best filtration system possible for them (e.g. canister filter) and be prepared to perform frequent partial water changes. They are known to rearrange their environment from time to time and to bash in to filter uptake tubes and heaters. If you are wanting to keep live plants in an aquarium you may not want to get one because they love to dig up plants. They are also very good jumpers, so a heavy hood is a necessity.

They will eat most flakes, pellets, frozen, freeze dried and live foods including any other fish they share a tank with that are small enough to fit in their mouths.

Also see the Care Sheet on the forum.

Astronotus ocellatus Albino Oscar

Oscar Fish Care Details

Scientific Name : Astronotus ocellatus

Common Names : Albino, Tiger and Red, Marbled Cichlid

Care Level : Easy, good for freshwater beginners with a large enough tank and those with an adequate aquarium filter and those willing to perform frequent partial Water changes.

Size : 13 inches (33 cm)

pH : 6 - 8

Temperature : 72°F - 80°F (22°C - 27°C)

Water Hardness : 5° to 20° dH

Origin / Habitat : Slow moving waters in the Amazon river. There is a non-native population of oscars is well established in South Florida, USA.

Lifespan : 10 - 13 years

Temperament / Behavior : They can be aggressive if not given a large enough aquarium. They have an "eyespot" near the caudal fin and it is hypothesized that this eyespot helps prevent predation from piranhas.

Breeding / Mating / Reproduction : They reach reproductive maturity at 4 inches and will form life long pairs. Keep the water temperature around 82°F (28°C) and provide a spot for them to place the eggs. A large rock would work well.

Aquarium Size : 75 gallon or larger.

Tank Mates : Not many - Bala Shark, Silver Dollar, Pleco and Jack Dempsey fish are some acceptable tank mates. However, don't put in any fish that are small enough to fit in the mouth of this fish.

Disease : Freshwater Fish Disease

Food : Omnivore, will eat flakes, pellets, freeze dried and live foods. Give them a varied diet with lots of protein.

Tank Region : All over

Gender : Can be difficult to determine. The female is usually smaller and less colorful than a male of the same age.

Photo Credit : Photos copyright JJPhoto.dk

Site References :

Fish Lore Forum : Oscar Forum | Oscar Fish Photos

Oscar Comments and Tips

From: BabyBoo
I bought my husband a Red Albino Oscar. My husband has never been fond of fish but he fell madly in love with the oscar who he named Claude. It's the best investment I feel I've ever made.

From: Darrel
These fish are seriously aggressive! I have had many over the years and all have been fighters. If the fish are small enough they will be eaten, only compatible sized fish should be kept in the same tank. I had a 7 inch oscar eat a 5 inch pictus cat head first, with all 3 spines stuck through the head of the oscar. The pictus died but the oscar survived with a little torque jaw after snipping the pictus spines off with diagonal cutters and pulling the fish out.

From: Larry
The agressiveness of these fish will vary on a fish to fish basis. I have owned many throughout the years and have had some that eat anything that moves, but the one I have right now is about twelve inches long and won't eat anything over one inch long.

From: Mellonie
I have my second set of them now, and they are a joy when it comes time for feeding. Be sure to feed them a variety of protein rich food with "live" food for snacks. If you aren't careful of selecting healthy "feeder fish" your fish will get sick. Be sure to watch closely, because the "live" fish usually don't last long.

From: Dennis
I alternate between hikari chiclid staple, frozen blood worms (thawed) and feeders. Make sure the feeders are small enough to be eaten in one shot as they make a horrible mess other wise. With this routine you should see about an inch a month growth. They are usaully super aggressive, easy to take care of, and are one of the faster growing fish available, making them the most popular and funnest tropical fish you can buy.

From: DeeDee
They are very spoiled and they eat other fish because they are very territorial. Buy one and enjoy the fascination that we encounter from investing in one.

From: Andrea
We just got our little guy 'A.J.' and he is fun to watch. He greets me whenever I come close to the tank. It's neat to know a fish can have a personality. He is part of the family now!

From: New Owner
I recently decided to try my hand at owning them. I started with two (along with two sharks) in my new tank only three days ago. I noticed that the two stay right under each other and follow one another around. It's really a shame considering that they have plenty of space to spread out. Is that normal? Also, I read other owner comments about these fish greeting you and acting almost "social". Mine seem to hide whenever I get close up on the tank. Am I doing something wrong?
No, you're not necessarily doing anything wrong. If you've only had them a short time, give them a little while to become acclimated to their new surroundings. They should warm up soon and become even more "sociable" or anti-sociable to their tank mates as they get bigger.

From: David R.
I started with two in my office fish tank. They were about 6 or 7 inches long. They chased each other around the tank. One morning I found one stiff as a board under my desk. Apparently, the fish knocked open the cover, so you might want to weight your tank cover especially if you have two or more guys. The remaining one is 6 or 7 years old and is over 12 inches long. He does not bother the African chiclids or Black Convict. They are all over three inches long. He loves worms and crickets, but mostly he eats green pellets. He absolutely refuses to eat the red pellets. he almost starved to death until I switched to green!

From: Karissa
I definitely believe that how they react to smaller fish in their tanks varies. I have a 4 inch one that lives very happily with a 3/4 inch long dwarf puffer. They will even eat right next to each other without competing. I used to have two, but the other puffer died after a fight with the oscar that the puffer actually started. They're both aggressive fish, despite a great size difference, but they live together just fine.

From: Mike
I have two tiger oscars and a red. Yes, these are aggressive fish, HOWEVER sometimes they will somehow actually tolerate a small fish in the tank. Believe it or not but I actually have a Cory Catfish (maybe an inch long) that has been living in the tank with mine for almost two years. It is my belief that once a fish is accepted into a tank it will for the most part be ok. My two tigers are 12" and 9" and my red oscar is about 8". This is not a recommendation to put small fish in your tank but just a comment that somehow some fish can pass muster and be accepted. My cory cat will swim up and down right in front of them and they don't give him a second thought. If I put tuffies or goldfish that are the same size and\or color they get eaten. I just put a baby Jack Dempsey in there (about an inch long) and they show some interest but he seems very adept at hiding so far.

From: Natalie
I have a 8 inch albino oscar, the love of my life, he is the sweetest thing in the world. He lives in a 180 gallon tank with an irridescent shark, pictus cat, jack dempseys, jewels, convict cichlids, and a breeding set of green terrors. He's like the daddy when the rest have an issue he takes care of all the problems. He is my puppy!

From: Clay
I got my first one and I love him. He is only about 2 inches but he will eat anything that can fit in his mouth. He loves to jump out of the water to get food from my hand!

From: Warren
I had a pair of them getting ready to mate and they play-fought to test each others strength. Unfortunately, one of them swam out of the tank, busting open the glass top. Tops must be secured or a mating pair will end in disaster.

From: Fleet
I have not had an Oscar in over 5 years, but I am going to get one or even a pair this week. They are fun too watch and they are one of the smartest fish around and can be very aggressive. My uncle got me in to them when I was about 8 years old. He had a very big Oscar and his cat stuck his paw in the tank and the oscar took a nice bite at it :) One thing I must point out they eat alot. Small Oscars and big ones and over feeding them will kill them, so keep that in mind!

From: Kaz
Hi there. I have just recently bought my first pair (possibly a breeding pair), Fat and Fin... I am feeding a high protein diet, with earthworms as treats. (They did have a nibble of the boyfriend that didn't believe that they would BITE!) The first earthworm I dropped in the tank they surveyed for some time. Now, they eat them before they hit the bottom of the tank... and no more boyfriends in their diet.

From: Drewski
I have a red and an albino oscar in a 55 gallon tank and they are great fish. I feed them feeder fish once a week, pellets, blood worms and brine shrimp. I try to give them the best variety of protein I can. I had 6 tiger barbs, now I'm down to 3 in 6 months. I had the tiger in the tank first, so I thought they might make it but I guess not. They also like to pull my blood worm feeder off the side of the tank and play with it, its so funny to watch.

From: Pablo
I have always known about them but only recently bought one (Gary). I can truly attest to their entertaining behavior and much enjoy buying snack fish for him, it keeps him occupied, fed and me entertained. What a great fish.

From: Usher
I just bought one and he just ate all my other fish. My small fish cost me 50 dollars and he ate them all. Even I don't have a $50 meal.

From: Michael
I recently bought 2 Tiger Oscars for my 55 gallon tank and they are doing great together. I bought them very small so they could grow up together and they seem to be pretty friendly towards each other. I have not noticed either one trying to be dominant. One question I have is, I have 2 Aqua Clear 70 filters as my filtration system and is this ok? I check the water ever week and all conditions are great. The fish are very healthy and have great coloration, I just want to make sure that I have a good enough system for them.
The aquaclear 70 is rated for 30 to 70 gallon aquariums and having 2 of them on your 55 gallon should be fine. Just remember to stay on top of those water changes and rinse filter media in discarded tank water during water changes.

From: Bec
I have 2 oscars, one is about 10-12 inches and the other is only about 3 inches. They are in a tank with a pleco (15 inches), a swordtail, catfish (9 inches), 2 angelfish, a lobster yabbie, a crimson tide an some feeder fish and feeder yabbies. They are all getting along very well probably because they are fed well. My large one will tap the side of the tank to let me know he is hungry and the others get excited by this. I feed them a native pellet and feeder worms, but they only get feeder worms when they chase my hand up and down the tank as I don't want to overfeed them. I also have a ball in their tank for them to play with.

From: Josh
I am a runner of a neighborhood freshwater aquarium, which we set up in an old agricultural goods shop. It consists of only two rooms, one to the front and one to rear, and we have oscars as one of the main attractions. These fish are great and people love them!

From: Primo
A few years back people had a misunderstanding that Oscars eat feeder fish and actually they will and be fine , but there is no nutrition in feeder fish. If you buy them from a pet store they might have a fish disease and could transfer to your Oscar, so I would recommend pellets, frozen shrimp, flakes, peas, lettuce, broccoli, earth worms, blood worms, crickets etc. You can also give them crushed vitamins. vitamin C, E and maybe vitamin B?

From: Chris
You should TRY live feeder crickets. Mine, called Leroy, goes absolutely crazy as soon as I approach the tank with them.

From: Ewolf315
22 years ago I had my very first Oscar and what a treat it was having him. They can eat and will eat everything in sight. Besides the usual feeder goldfish (25 at a time), he ate garden snakes, nightwalkers, minnows, crayfish, frogs and even gerbils. This fish was the Tiger variety and was 15 inches in a 55 gallon tank. One day I went to the local pet shop and decided on getting him a room mate, LOL. That was a mistake as he bit the fish right on its back, and it was a 20 inch Iridescent shark. The only other fish he was able to live with and didn't bother at all were 2 kissing fish. He lost his life when my house burned down and I sure miss him.

From: Tyler
I have 3 and they are so fun to watch. My biggest one (12" tiger) is in a 55 gallon tank with a firemouth cichlid and some electric blue haps. My other two (tigger and a albino) are in a 180 gallon. they are very curious fish that like to see what I'm doing. I feed mine tropical flake food, blood worms, pellets, crickets, and small fish (not feeders because they can give your fish disease). So do not feed them feeders. These beautiful fish can get hole in the head disease if you don't feed them the proper diet. Have fun with your oscar or oscars!

From: Big Daddy
I got my tiger oscar "Chancho" about 1 month ago or so, at about 2 - 2.5 inches, along with a jack dempsey which was about 1.5 inches. I keep them in a 55 gallon tank with a 9 inch pleco. I am running a penguin 330 power filter along with a fluval 305. I think filtration is very important, as Chancho is quite messy and keeping these 3 large fish can be taxing on such a small eco-system. My Chancho is now about 3.5 - 4 inches and is quite picky with what he eats, and eats out of my hand... He will actually come up out of the water and snatch it out of my fingers (totally cool). I have wanted one for so long and I am so glad I have one. Within the next year I plan on getting a 155 gallon tank, and transplanting Chancho and his friends there and perhaps take a stab at breeding them. They are wonderful fish.

From: Tay
Ok, so there I was in a local department store gazing up at the poorly looking oscars in those 10 gallon tanks. Of course I pitied them and brought one home. I am planning to upgrade to a 75 gallon tank as soon as he grows out of my 29 gallon. He is in there all by himself. When do you think would be a good time to move him to the larger tank. I have heard that they will grow an inch per month. He is four inches right now. Any reply would be greatly appreciated! P.S. Is it true that they need more room growing up than when they are full grown? Thanks!
I'd move him to the bigger tank as soon as possible. You'll be providing a much better environment where he will grow even faster and stay healthier. I'm trying to understand the thought process behind the last question... Do people think that because they are less active as they mature that they need less space? I would disagree. The bigger tank you can give this wonderful fish, the better.

From: Misty
We have had our fish for a year and just got another one about 3 months ago. We love them. The oldest one is about a foot long and he and my 2 year old daughter give each other good night kisses every single night. He is the best pet we have ever had!

From: Rhino
HELP! I went to the pet store and bought a 10 gallon tank, with all of the suitable requirements, (tank cleaner, ornaments, filter, etc.) Then I foolishly decided on a tropical fish I liked, Albino Oscar. When I asked the pet store employees, they said that a 10 gallon tank was ok for mine. I've since found out they grow much larger. I really Love my fish but simply can't care for one that grows that big, especially with my tank. Will stores take him or what should I do?
If you're not willing to get a much larger tank, at least a 55 gallon, please take your fish back to the store you bought it from and get a refund. Also, please talk to the store management about how their employees told you that Oscars would be suitable for a 10 gallon tank. The store owner/manager needs to educate the employees on this... This is bad business and a good fish store wouldn't have sold you this fish.

From: Hans
Recently I bought one. When I got home it was just laying on the bottom. I thought he was dying from the shock of the move. I had six guppies in with him and he didn't even touch them. The next day I woke up and looked at him. There were only 4 guppies left and by the afternoon all six were gone. He began to eat anything I offered and he even nibbled my finger! Just goes to show you that patience is key. I just needed to give him time to adjust to his new environment, that's all.

From: Dawson
I find that if you keep them in a small aquarium that they will become more aggressive. But if you house them with the right amount of space they will become less aggressive. I have 3 - a huge 14 inch oscar a 8 inch one and a 5 inch. They all live in a 200 gallon fish tank. I can pet them to. This might not work for all people but it has always worked for me.

From: Trevor
Oscars are great! I have a tiger and a green terror in a 55 gallon aquarium and they get along great. All I really need to do is grab another heavy duty HOB (already have one). I would really recommend picking one of these bad boys up if you are willing to put the time into it!

From: ms_omg25
I just got my first one and he is wonderful! I have him in a 125 gallon aquarium and he swims all over and actually DOES greet you! He ate all my guppies though... lol.
Yep, to be expected from this cichlid.

From: John T.
Well, I've had them for 2 years. They are great to have in the house. They live long and grow about 13 inches so you will need about 55 gallon tank or higher to live in and never put any fish that could fit in their mouth because they will eat them. They will greet everyone that comes near the tank.

From: Jordan
I have two tiger oscars one which is about 13 inches the other is about 14 inches and they live in a 75 gallon tank. I've had them for 7 or eight years now. Their diet consists of protien pellets and complete cichlid frozen meat. Their tank mates are 3 jack dempeseys, 4 chocolate cichlids, 9 silver dollars, and various catfish. I've heard they live up to 10 years but I'm hoping to break that record!

From: 3 Oscars
I have three Oscars in a 125 gallon (6 feet long) aquarium with one large sucker fish. All are 14 to 16" long, including my sucker fish which looks like a dragon now. He's huge, lol. I have had them all for 6 years and only feed them pellets. I use 3 canister filters which pumps 1,100 gallons per hour. I never use carbon, only bio media and filter pads. I change 25 percent of their water only once a month. The filter pads are also changed once a month, but not at the same time I change their water. I do not rinse thier bio media, ever! (keeping good bacteria alive is extremely important) I also use Purigen bags and use twice as much as recommended. Argonite sand is mixed in their gravel as well. The Purigen, sand, and 3 filters seem to keep the nitrates low. I may check their water for nitrates only once every six months and it always comes out great. A 125 gallon aquarium is usually too small for fish as large as these, but they have 6 ft. to swim and excellent filtration!

NOTE: When I first got them, as babies, I had a 55 gallon aquarium with 1 filter. NOT ENOUGH! Then I bought a second canister filter to help out. The two canisters helped tremendously with nitrates, but they were getting aggressive towards each other the larger they got because they did not have enough room to swim around. Then I bought the 125 gallon aquarium when they were less than 1 year old! I was finally able to enjoy mine and it was clear to see they were much healthier and happier. They swim side by side along the length of the tank :) Anyone who buys cute little Oscars, beware. You need lots of filtration and a large aquarium. They are the coolest fish when they are big, healthy, and happy. Everyone "aw's" over my Oscars and can't believe how large they are.

From: Carl
Mine is the opposite. He won't eat the green pallets he only eats Red ones.I have african and south american cichlids and they all get along and My fish has his own personality. If I seat at my computer and don't look at him, he bumps the side of the tant until I look at him. He is my favorite fish.

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