Oscar Care

Wilhelm Joshua Tan
  • #1
Veterinary & Aquatic Services Department, Drs. Foster & Smith, Inc.

Astronotus ocellatus

Quick Stats: Oscar
Family: Cichlidae
Range: South America, Amazon
Size: Up to 12 inches
Diet: Carnivore
Tank Set-up: Freshwater: Deep sand, potted or floating plants, large rocks
Tank Conditions: 72-77°F; pH 6.0-8.0; dH 5-19
Minimum Tank Capacity: 70 gallons
Light: Medium
Temperament: Semi-aggressive
Swimming Level: Middle to bottom
Care Level: Difficult
Reproduction: Egg Layer

The Oscar, also known as the Marble or Velvet Cichlid, makes a great addition to a large aquarium. There are several color variations including Albino, Red, Tiger, and Zebra. The Albino is pale orange-pink in color and may be missing the eyespot. The Red is orange-red with dark gray shading and an eyespot on the dorsal fin. The Tiger has a blue-black background with an orange-red pattern and its dorsal fin has an eyespot that is very brightly colored. The Zebra is black and white with gray shading and an eyespot on the dorsal fin.

The Oscar requires a large aquarium of at least 70 gallons with a deep sand bottom and a few large rocks. It will dig up plants; so any that are in the tank should be potted with the root surfaces covered with rocks. Using floating plants is a good option to avoid this problem. Cichlids are hearty eaters and should only be kept with other fish that are of the same size, as they will eat any that are smaller than themselves.

The male and female Oscar will form a pair, make a nuclear family, and are generally peaceful. It is difficult to distinguish between the male and female, but during spawning, the female has obvious genital papilla. A large tank should be used for breeding, 100 gallons if possible. The Oscar will spawn in soft or hard water as long as the water is clean and clear and has a temperature between 79-86°F. The female will lay from 1,000-2,000 eggs on rocks that have been carefully cleaned. The eggs are opaque at first, turning transparent in 24 hours. The brood will be carefully guarded and cared for and the fry will be kept in pits and may even be covered. When they are free-swimming, the fry should be fed Cyclops. Sometimes, the fry will cling to their parents.

The Oscar is a carnivore that is a predaceous and hearty eater. Cichlids will eat a variety of meaty foods, including small fish and earthworms, Cichlid pellets, larger flake food, ocean plankton, bloodworms, and tubifex worms.

Ideal tank mates include similar sized:

Other South American Cichids
Scavenger Catfish
Similar sized fish (miscellaneous fish)
Photo Credit: André Mantz
For sale online at:

Buy & receive at home! ->
Tiger Oscar
Albino Oscar
Red Oscar
Zebra Oscar

Name: Astronotus ocellatus
Size pH GH Temp
Origin: South America
35 cm 7.2 10 26°C

Oscars grow very rapidly, as much as 3 cm per month if well fed, sometimes more. They tend to slow down at 18-20 cm, but will eventually reach 30 cm. Stories of 40 cm, although rare, are not impossible. They do not need to be kept isolated - some company tends to result in a livelier and happier fish. But don't mix them with aggressive cichlids such as the Jack Dempseys or Convicts, unless the tank is very large (600+ liters). Can be kept with Severums and other big peaceful cichlids. Put some 'dither' fish with them, such as Giant Danios or Tin Foil Barbs - they keep the Oscars active and eat a lot of left over food.

Minimum tank for one specimen would be 120x45x45 cm (250 L, and in my opinion a tank this size if well maintained can also house 'dither' fish) and an external and internal filter highly recommended. Bright lighting tends to increase aggression. Avoid sharp decorations, Oscars are forever banging into stuff and damage easily, although they heal remarkably quickly, especially if water quality is maintained. Keep the water well filtered and clean - by doing so your Oscar will rarely (if ever) get a disease and you will save yourself a lot of hassle in the long run. Hole in the Head Disease (HITH) can be prevented by feeding a varied diet and maintaining good water quality. They are not sensitive to water chemistry as long as extremes are avoided. They love and thrive in clean fresh water (obviously dechlorinated). Ideal temp of 26-27°C. Change 20% minimum a week, and 50% maximum a week - any more and you may disturb the good bacteria present in your filter and cause more problems with your biological filter.

Feed them a varied diet - prawns, earthworms, bloodworm, shrimp, bugs, etc, plus a good quality cichlid pellet. Experiment with different foods, some foods tend to be wafted out all over the tank, others gulped down in one. You can to some extent control the pollution with certain foods, e.g., some pellets are gulped down, other brands are wafted out, trial and error. Do not feed feeder goldfish, unfortunately the only purpose they serve is to entertain. They are high in fat and unless you quarantine them they could carry disease. This is very important - feed a big juicy earthworm instead - just as much fun and very high in easily digestible protein.

Summary: Unfortunately a highly abused fish that rarely is given the space and care it needs to THRIVE. They are highly intelligent fish, that will bond with people and other fish alike. They are easy to keep due to their hardiness, however this often means they are subjected to poor conditions. Caring for them properly is more of a challenge, and anyone thinking of keeping them should take into account their requirements, so before you buy an Oscar - do some research! Enjoy!

Contributed by Simon Cooper
A beautiful and personable fish, they are easily bought very inexpensively at a small size, but the eventual size of the fish should be considered before purchase. A 100 gallon tank would be considered to be a minimum size for a pair of these fish. A high-volume filter is also a necessity, as the fish are messy eaters, and regardless of tank size, regular water changes should be performed in order to keep the fish in good health. Meaty foods, especially live foods are recommended, but if feeding goldfish or other "feeders", be careful not to introduce disease to the tank.

Contributed by Lyn Fincham
Oscars can be hand fed and I think they like gold fish better than pellets. I also know that it is best that you have a lid on their tank, because I had some that made a sky dive unto the floor and I made it there two weeks too late!

Contributed by Russ Klein
Oscars are excellent predators, and they do like to be hand fed, only make sure you have ten fingers when the feeding is done. When you add fishes to the aquarium, make sure they are quick, so they can get out of harm way in time.

Contributed by Uzi
I had an Oscar that I just loved! He would only eat goldfish....and any other fish! When I first bought him, he was a little baby, but soon I realized the little baby wasn't a baby anymore so I had to buy a 20 gallon tank! When I first bought him, he would eat nothing but flakes, but one day when I woke up, I realized that I was missing a fish, the Oscar had part of the fish in his mouth! I was so mad but I looked at him and he gave me a look like..."well I was hungry"! I love Oscars and one of these days I'm going to buy another one!

Contributed by Richie
I used to have a large, male tiger oscar. He was large in size, but his personality was even more immense! In between feedings of cichlid gold and goldfish, I would feed him large crayfish. They would raise their claws in defense, but he would dart at them so fast that their claws would pop off and their body would be stuffed in the oscar's always hungry mouth. You could hear the crunching through the glass!

Contributed by Andrew

  • #2
Hey, good job Wilhelm! i've added some tips too, i've been doing a lot of research on Oscars recently!

Tips on OSCAR Fish

This article will help you a lot if you are a new Oscar owner, so please read before you start though it is a bit lengthy.

Oscars get very big in a relatively short space of time. They are also very messy fish, both in their eating and toilet habits. You’ll need at least a 55 gallon tank for 1 Oscar, but if u want tank mates a 125 gallon tank would be perfect. Oscars may grow up to 12-18 inches and live up to 10-15 years. Oscars grow pretty fast, a juvenile Oscar will grow 1 inch a month in the first six months and then it will slow down. Roughly, an Oscar should reach around 7 to 8 in. within the year, after that, their growth rate slows right down. You won't notice a rapid increase in their length; however, you will notice that they bulk up considerably. A two or three-year-old fish could range from nine to 12 inches.

Oscars come from the tropics so they need to live in a heated environment. The temperature of an Oscar tank should be between 21°C and 28°C although Oscars will be okay with water up to 30°C. Just remember that the hotter the water, the less oxygen there will be in the water so it's important to watch out for signs of oxygen depletion, especially in summer. A telltale sign will be fish opening and closing their mouths a lot.

When keeping Oscars, you have to bear in mind that these fish like excavating and moving things around. If you want a pretty tank with lots of nice plants then don't bother with Oscars. Every Oscar owner will tell you that plants don't last very long in an Oscar tank. For some reason, Oscars love uprooting and destroying them, it is very common so don't be surprised if this happens to you. You can give them a handful of rocks to play with.

Sometimes you may notice your Oscar sitting on the bottom of the tank; you may also even see your Oscar laying almost on its side. In most cases, this strange behaviour doesn't last very long. Oscars are not the most active fish; in fact, they can be really lazy sometimes. However, they normally respond when you are anywhere near the tank.

Oscars are what we call monomorphic. This means that males and females look the same. Unfortunately, you won't be able to go into a shop and choose a male and a female like you can with other species of fish such as guppies. Only when Oscars start laying eggs will you know for sure that you have got a male and a female. The females egg tube is round and the males sexual organ is pointed and looks rather like a thorn.

Oscars will eat bloodworms, pellets, earthworms, dried worms, crickets, shrimps, prawns, insects, small white fish, feeder fish etc. In the wild 60% of their diet is made up of insects. Rivers shrimps are very good diet for Oscars. Oscars need lots of protein, and a poor diet may result in a disease called Hole in the Head (HITH), which is fatal for them.

Oscars like to be boss. There are various fish that could pose a problem if mixed with Oscars; some of them are the Jack Dempsey, Terrors, Flower Horns, Parrotfish and Blood Parrots. If you want community fish such as Tetras, Mollies etc., put them in a tank of their own because they probably won't last very long in with the Oscars. Some suitable tank mates are Clown Loach, Green Severum, Tinfoil Barb, Bala Shark, Silver Dollar and Common Pleco. It is better not to keep 3 Oscars together because 2 of them may team up and attack the other.

Wilhelm Joshua Tan
  • Thread Starter
  • #3
But I have an oscar already in Cartimar in the Philippines.
  • #4
Sorry Josh:-\! I don't get it.....what do u mean
Wilhelm Joshua Tan
  • Thread Starter
  • #5
I have an oscar already.
  • #6
I've been watching my friend Tony's Oscar for months; he inspired me to buy a big tank for a oscar, so I did a lot of studies about oscars so that I can take care of it when I buy one, i'm cycling my 100 gallon now, I will buy 1 oscar soon! well, read my tips and see if it is ok, let me know if anything is wrong. I thought I should share with u guys what i've learnt.x


Wilhelm Joshua Tan
  • Thread Starter
  • #7
How big is Tony's oscar
  • #8
Well, he bought it last December, was only 3.5" then but now it's 6", they grow pretty fast, no! Tony feeds him shrimps, bloodworms, small fish and pellets, Tony also has 1 Bala shark in that tank. it's a 150 Gallon. how big is your one?
Wilhelm Joshua Tan
  • Thread Starter
  • #9
It is small.
  • #10
how come so many of you have such a huge tank??
100 gallons tank is really really big (@..@)
Wilhelm Joshua Tan
  • Thread Starter
  • #11
More for you to begin an oscar

Before you buy

If you already keep fish you probably have a good relationship with a particular aquatic centre, maybe more than one. However, if you are new to fish and are looking to buy your first Oscar and please don't walk into a fish store and buy the first Oscar that you clap your eyes on. It is good practice to vet a supplier. Just because they sell fish, it doesn't mean they are competent and good at their job, anybody can open up a fish shop.

Have a wander around the shop first, is it nice and tidy and clean? Is there rubbish left on the floor? if you find that this is the case, you can bet your bottom dollar that their maintenance regime isn't up to much. A tidy shop tells you a lot about the people who run it. Have a look in the tanks, do they look clean and well cared for? Is the glass covered in algae? are there sick and dying fish left in the tanks ? However, if you see tanks that are clearly marked "quarantine" or "not for sale" this would indicate to me that the people who run the premises have a responsible attitude. This alone tells me that there is a good chance they are selling healthy fish.

Before I ever purchase fish, I like to have a chat with the owner, if they have a good knowledge about fish and are willing to take responsibility if fish bought from them become ill very quickly, I will certainly have no qualms in purchasing fish from them. I also like to see separate filtration systems on each tank. I'm not keen on one filtration systems servicing all the tanks. Whereas this is a good way filtering tanks, it can also have a detrimental effect, especially if one tank suddenly becomes diseased. Finally, I like to see water changes being carried out during shop hours, even if it's youngsters who have been employed to do the job.
  • #12
Notescars are omnivorous in the wild.
They eat wild fruits in natural habitats that fall into the water .

feedyour oscar some melon, he'll be much healthier.

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