Breeding and Caring for the Oscar Cichlid (Astronotus Ocellatus)

Oscars are a fish native to the Amazon. They can be found naturally in areas like the Amazon River Basin, the Parana, and the Rio Negro.

As young, the Oscar will tolerate living in groups but as they get older they are much more inclined to form pairs and become very territorial. They will often change color under many situations: aging, stress, forming territories, etc.

They are a very popular fish in the aquarium trade due to their personalities and ease to keep.

Quick Stats

Other Names: Oscars, Marble or Velvet cichlid

Scientific Name: Astronotus Ocellatus

Maximum Size: Upto 15 inches

Lifespan: 10-13 years

Behaviour: Aggressive if not given a large enough tank

Minimum Tank Size: 75 gallons / 340 liters

Keeping Oscars

You may see Oscars in most pet stores and yes, the young smaller specimens look cute and friendly, but before considering buying them think about how you will keep them.

They grow fast, often reaching around 6 inches in their first year. They are best kept individually or as pairs in a single species environment. Because of this be sure to keep in mind your budget, space and what it is you want from the fish. Is it all achievable?

By this point in the article, you should have decided whether it is something you want. If so we will get to a more detailed analysis of the fish.

As previously mentioned Oscars are a very popular fish, they are a South American Cichlid and behave in a way typical of this type of fish, they are destructive creatures and will often rearrange an aquarium or break equipment.

However, they also have real characters much like that of a puppy, they are very excitable and prone to seemingly odd behaviors for a fish. They have been known to get excited when you get home from work, to what seems like beg for food around meal times and strangely I’ve witnessed them learn the voices of their owners/carers.

It is very easy to see why they have become so popular in the hobby to date, even I have been thinking about getting a pair away from the retail environment and into my own home.

They come in a small variety of colors and common names listed in pet stores, the common ones you may come across are Marble Cichlid, Velvet Cichlid, Albino Oscar, Tiger Oscar and Red Oscar.

Before making the purchase of your new best friend, treat them as any other fish, get the aquarium ready roughly a month beforehand.

The Tank Setup

Water Conditions

Oscars are a very hardy fish coping with a wide range of water conditions, however, they should be ideally kept in the following ranges:

pH: 6-8

Water Hardness: 5Dh to 20Dh

Temperature: 22-27 ℃ / 71.6-80.6 ℉

The Décor

Everything other than the gravel should be stuck down so before adding water, get yourself a bit of aquarium sealant/glue. I recommend using the HA6 Silicone Sealant, it has never let me down and I always use it.

The gravel is completely the choice of the keeper, but bare in mind that small, fine gravels will be disturbed much easier than that of larger grade gravels.

It's not a good idea to use plants, they will be destroyed or uprooted regularly and so if the aesthetic appeal of plants suits your needs then go with fake ones.

Fake plants with silk added to the material do have a more natural look in the flow of the water but will easily fray and look ragged in a short period of time, so, unfortunately, full plastic is the way forward here.

My favorite fake aquarium plants are those in the Hugo Kamishi range, they look the most realistic (rarely any stupid neon unnatural colors). Fake plants should be stuck down also.


Usually, any rock would do, and you will often find that in pet stores, the store worker will say that any rock will do. But this is where experience favors over general recommendations.

With the aquarium being a large one, small rocks look out of place, because of this owners tend to go for the larger rocks. This is the right thing to do, but don’t go for rocks that are jagged or sharp, due to the destructive nature of this fish the will scratch themselves.

It is best to go for more rounded or smoothed rocks and wood.



With a tank of this size and the nature of the fish, it's probably not a good idea to go for an internal filter. Use an external, and one that will do much more than the aquarium volume as they will make a mess.

I may even be tempted to go for a medium sized pond pump, they are after all designed to cope primarily with the waste of Carp (use expert knowledge when considering this option).

My top choice may seem expensive, but its well worth the price, it is the Eheim Pro 4+.


The standard glass heaters won't do, they break easily with Oscars and this can make serious consequences. So plastic heaters are a must have, an easy choice is the Fluval E300. It even comes with a digital display on the current temperature and flashing alerts on the LCD display.


Here there is no need to go for anything fancy, without the need of plants to satisfy any lighting will be sufficient. I do still have my top products, though, so for aquariums with a transparent lid, I would choose the AquaOne Tropiglo

It's an easy to use LED system with 2 switches on the lighting panel with both white and blue LEDs, the option to have either just white or just blue or even both at the same time provide an easy option with just the one plug socket used.

You might want to consider some other high-quality LED lighting options​ for your tank.

Feeding Oscars

If done correctly and from a young age, Oscars will take a vast array of foods and are in fact, I’ve found, one of the least fussy fish to feed.

If they are fed without a range of different food they will become accustomed to only these foods and not readily accept others as they mature.

Because of this it's recommended to feed them as much of a varied diet as possible from a young age, they will pretty much eat anything that will fit into their mouths too, dietary options include (but are not limited to):

  • Insects (crickets, locusts, earthworms, etc),
  • Fish (frozen Lance Fish, live feeder fish),
  • Dry foods (Pellet, Large flake),
  • Plants (Frozen Plant cubes, Vegetables, Plant based Flakes or Pellets).

Sexing Oscars

Sexing Oscars is extremely difficult, even to experts. There are various methods, none of which is definitive.

Some say to look at the ‘eye spots’ on the caudal fin and sometimes on the dorsal fin, those with the smaller spots are usually male. Others look for differences in abdomen shape or fins. Someone else says it's impossible to sex these fish (monomorphic, males and females look the same).


If a pair of Oscars is luckily obtained, then breeding them becomes easy.  

Given that the pair like and accept each other, they spawn in the typical manner of large cichlids, they will find a suitable place to spawn and place the eggs on large rocks or wood.

They may begin breeding at a young size of just 4 inches in length, but these first attempts may not always be successful. As they become more accustomed to the spawning process they may lay as many as a thousand eggs every few weeks.

Unless you have a vast amount of money to put into raising the fry, I would not attempt to breed in the hopes of making money from Oscars.

Closing Thoughts

On the whole, it is very easy to see why Oscars are so popular, with the ability to tame them into hand feeding, who knows where the intelligence of the fish will stop with a mixture of constant attempts and loving care.

Oscars are less of ‘just a fish’ and more an actual pet. Those who keep Oscars, love Oscars.

I have one in my workplace that is a Tiger Oscar nicknamed Ember because her (assuming it’s a she) colorations looks like the embers of a fir. She’s not my biggest fan, I care for her, maintain her water, clean her filter, etc. but she favors my colleague that feeds her.

When she sees her feeder she is straight up to the side of the tank begging for food and being generally playful.

This isn’t properly relevant to this piece of work but just showcases the personality of the fish and the fact they are actually a very intelligent fish.

So, if you’ve got the tank size, get an Oscar (or two) you won't regret it.