Oscar Fish Facts

Scientific and Tank Facts

Scientific Name: Astronotus ocellatus
Family: Cichlidae
Origin: South America
Adult Size: 12-18 inches
Social: Semi-Aggresive
Lifespan: 10+ years
Tank Level: All levels
Diet: Omnivore - Eats flake initially then moves to pellets
Breeding: Egglayer - may breed in aquariums
Care: Moderate
pH: Neutral
Hardness: 15 dGH
Temperature: 74-80 F 

Facts, Observations, and Hearsay

Observation: They are very smart fish

I have found that oscars are very smart fish. They adapt quickly to their environment as well. My oscars seem to know what is going on around them. They will follow a persons finger and have no fear when a person approaches. I have heard them called the " dog" of the fish world. Observation: Interaction with other fish

There is definitely a pecking order with fish. From the first day we had the oscars they knew who was the largest of the two and who got to eat first. The larger dominant one chased the other around continuously. At this stage of the game, they definitely use their size to get their way. We found that the smaller oscar eventually became larger and then the tank was evened out and neither fights the other. They are aggressive with other fish as well and will run other fish around. However, they never actually bite a tank mate, unless it is smaller and considered a meal. They commonly chase. 

Found on the net: Origin

They can be found in Central and South America and other areas. They are now more wide spread in tropic areas because of dispersion by humans. 

Found on the net: Taxidermy difficult

Because not a high enough demand of people tend to taxidermy their oscars they are unique to taxidermists. They must be carved before the skin can be stretched over them. It is very uncommon and pricey to have them taxidermied.

Instructed: Salt is like gatorade to a fresh water fish

A Petsmart worker explained that the correct amount of salt is provides necessary electrolytes to a fish. They are able to breathe better because of the effect of the salt on the gills. Too much salt can make a fish ill and kill it. For oscars about 1 tablespoon per 5 gallons does fine. Be sure to account for evaporation. As the water evaporates the salt content rises. 

Quoted: They can become very friendly

That say the fish will eat right out of the owner's hand. It can be spooky because they are so aggressive and can actually nip at a finger. I have unintentionally held a pellet out of the water while one of the oscars ate another pellet and by surprise the second oscar comes clear out of the water after my hand. It is not healthy to handle the fish a great deal because human oils can be dangerous. Besides, oscars have spines and a wound to the hand can become greatly infected.

Experienced: Watch out for the water heater

I have heard that oscars will attack a water heater because of the light in them. I know there are special durable heaters that can be purchased. As well, some people hide the heater behind some type of decoration. 



beca - Sep 01, 2016 03:25 PM EDT

My oscar is a very aggresive oscar and i noticed his change when his partner passed. Now i have tried to keep him company by introducing him to other fish which he eventually has as his snack. The only fish he hasnt attacked is my sucker fish. What fish would many of u recommend i introduce to him that he wont eat?


Normacullop@yahoo. com - Apr 22, 2016 07:09 AM EDT

My Oscar is about two inches long he had swallef a guppy the tale is still hanging out of his it has been about ten minutes should I try to net H and pull the guppy out he does not seem to be be in distress at this time.Please help!!!!!!?


william archer - Feb 01, 2016 01:47 PM EDT

can oscars eat each other


kell - Oct 21, 2015 09:25 PM EDT

How can u tell if a Oscar is male or female?

Oscars are territorial

Michael pesek - Oct 14, 2015 01:23 AM EDT

If you had two oscars in a 10gallon or 30 and lower they will fight because they don't have enough room. They are very territorial especially if your Oscar is quiet large say maybe 4 inches+. I have a 8 inch Oscar in a 40gallon with a Plecoptera and alleged eater and he is very healthy and happy. I will be getting a 55gallon pretty soon here and maybe getting a jack Dempsey as a tank mate. But you shoul not have a Oscar that is exceeding 4inches in a tank under 40 gallons.

why my both the Oscars(4-5 inches) have started fighting?

anonymous - Jul 06, 2015 02:20 AM EDT

I have two Oscars in my tank, as we started keeping Oscars just before some weeks, we were not knowing that they need at-least 55 gallon tank, so we kept them in a 10 gallon tank. there size is about 4-5 inches, i saw that when i washed my tank and added two artificial trees and one heater and also changed the place of my filter, what i saw is, the day i did the changes, my both Oscars started fighting with each other and are also not eating their pellet food, but when i gave them a big ant to eat, they ate it very quickly. so, please suggest that this has happened due to small aquarium, because i changed the place of my filter, i added two plants or this has happened because as they leave food for some days and then start eating? They have not eaten food since 4 days. please suggest as soon as possible.

bad doggy

luis - Mar 23, 2015 11:26 AM EDT

Well i had 2 oscars in the same tank until one of the oscar was always scared of the other one until i had to put him in a different tank

bad osca

petsy - Jul 14, 2014 03:27 PM EDT

Had two Oscars of same size an eventually one grew bigger an better....until the smaller Oscar died and now d big guy is really aggressive even to fish of its own kind....and eventually ate them...

i have 5 oscars and i keep them in a smakl tank and they always fighting with each other and iqm si ecicited to see the change of color.

re water heater

talhia - Mar 08, 2013 06:22 AM EDT

we have a water heater, sadly our last oscar loved the heater too much and broke four of them before getting a fatal shock. so i would suggest a heater cover.

We love our little water dogs they love fruit an anything that would fall in the rivers streams an creeks that they would incanter in the wild


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