Aquarium Species: Oscar Fish

The Oscar fish is one of the most popular aquarium fish in the world. It’s sold as a “beginner” fish but I would personally disagree with that just because of the tank size the fish needs to live in. Blah blah blah! Life is short so let’s start this 7 step care guide.

  1. Needed Tank Size
  2. Tank Mates & Roommates
  3. Water Quality
  4. Protein Rich Diet
  5. Water Changes
  6. Destructive Tendencies
  7. Years Down the Road

** Let it be known that this is my personal care guide. Things can be done differently, but I just try to help others with what I’ve learned through my years of keeping oscars. If you disagree with anything or have questions MAKE SURE to comment below. I enjoy hearing what you guys have to say.

1. Needed Tank Size

The Oscar fish is sold as a beginner fish at Walmart and a lot of pet stores but I don’t agree with that. The fact that these fish grow up to 15 inches long means that need a large aquarium. What beginner starts with a large size aquarium?!? None. All beginner start small and work their way up usually.

You can start your fish off in a smaller tank and move up in time but they grow FAST! You need to upgrade as soon as possible. 50 gallons and up in size. Amazon sells some great acrylic tanks that ship pretty cheap because they are super light.


2. Tank Mates and Roommates

If you want to keep other fish with your Oscar make sure to be cautious. Oscars are super aggressive and territorial. All fish have different personalities and for the most part.. oscars are mean fish. Common tank mates include silver dollar fish, other oscars, arowanas, and some catfish.

There are two routes you should plan to go. You need a fish that either has an attitude of its own or… keeps to itself and bothers nobody. Catfish usually sit on the bottom and leave everything alone in the tank. I personally kept a catfish with an Oscar for years and one day came home… and it was in pieces…?!? The Oscar got bored.

Having tank mates truly is playing with fire when it comes to oscars. Sometimes the fish get along just fine for an amount of time and then… Bam! The Oscar strikes. Use caution.

3. Water Quality

I’m not here to preach to you how to take care of your fish aquarium but instead stress the illness that oscars commonly get from bad water. When it comes to keeping large fish in aquariums…. you need to step up your game on water filtration. There are TWO ROUTES to go. You can do a lot of water changes or you can get a good aquarium filter.

oscar fish care

Water changes are extremely annoying to me personally so I choose to buy good filters. I’ve had the best luck with AquaClear 110s. They don’t look like they would do much but they pack a punch. Do some research on reviews and you will quickly realize I’m not the only fan. You can also run a sponge filter on an air pump to add another layer of filtration.

4. Protein Rich Diet

People try to preach that “this” food is the best or that food is better but it all comes down to VARIATION. Think of what the Oscar fish eats in its natural habitat. It’s not going to eat the same food over and over (not to mention that’s not healthy). It’s very easy to get into a bad habit of always feeding your fish the same thing. DON’T DO IT.

*Here is a screenshot from Amazon of some good brands that have been around for decades. Brands like Hikari and Omega One.


Foods include: mealworms, crickets, minnows, leeches, roaches, any insect it eats, fancy guppies, frogs, shrimp, crabs, beef heart, fish fillets, and more. Just remember the saying “too much of anything is bad for you.”

** There has been a lot of arguing about feeding your fish live food because it is seen as immoral. I understand the point of view but… just know we’re not here to argue but instead to teach others how to care for oscars effectively.

5. Water Changes

This is Fishkeeping 101 and we sometimes forget with all our fancy filtration machines that we still need water changes. I understand that it can be super annoying to do a water change but try and make it easier for you. Buy a pump or… use a python water changer.. I don’t want to talk too much about this. Do your water changes!

6. Destructive Tendencies

Oscar fish get destructive inside aquariums! They will destroy live plants, move decorations, spit rocks, stir up sand, harass other fish, jump out of the tank, rearrange everything, etc! Fact of the matter is you need to plan for this.

I personally like to use very large gravel so they don’t create a huge mess. I decorate with fake plants but they usually get torn out of the gravel within one day.

** Use a cover over your aquarium because these fish will jump right out and die on the floor. Happens all the time to people.

7. Years Down the Road

It’s easy to show interest in your fish aquarium right when you set it up but after a year down the road.. you may get bored of it. Make sure to keep up on feeding your fish and doing water changes, changing filter pads, etc. It’s easy to forget about your fish because it only takes a couple days for you to screw up.


In Conclusion

Oscars are generally a really easy fish to care for as long as you have a big enough tank, keep up with water quality and feed them. It’s truly that simple. I love oscars because they’re a huge showcase fish with vibrant coloration. Make sure to comment below and questions or regards.


Have Anything to Say?


Posted by Ashley K:
Does anyone know the how small of a Jack Dempsey I could put with an 7 inch Oscar? I have 2 Jack Dempsey’s about 5 inches and looking to buy the Oscar off a friend. I was thinking I could do it if I have enough hiding places but I’m not sure.

@Reply: My Jack Dempsey was given to me for killing a larger Oscar.

@Reply: I’m tempted to try it. My jack Dempsey’s stay together and leave the other fish alone. I know they shouldn’t be with these fish, but i have them with mbuna and no issues. Separating them soon.

@Reply: You know it’ll be a problem. Hope you have a big tank.

@Reply: Size wise they should be fine as long as none are bullies my jacks dont start no trouble but they will finish it.

@Reply: Mine are pretty relaxed. Had them for a year in my mbuna tank and they never start anything.



Posted by Mike R:
What would you do? My siphon vac was left out on the patio to dry Sunday and I forgot it was there when the pest control company was out yesterday to spray. I don’t think it was sprayed directly, but may have gotten some pest spray on it. I have soaked it in the sink with a bleach/water solution and am now rinsing it and soaking it in water. Would you still use it? Would you do anything else to clean it? Would you just buy a new one? Thanks in advance.

@Reply: I’d buy a new one. I once last a couple of fish by opening my door to go out and then back in while my bug guy was spraying outside. The poison still made its way into my tank. I now turn off pumps and cover tanks with wet towels when I know the house will be sprayed. You can never be too safe. You should also always keep a heater in your oscar tank.



Posted by Leanne Y:
I was wondering what people do for algae control?
I have a 20 tall low-tec planted tank with a finnex planted plus 24/7, with 3 ottos and 4 nerite snails and they don’t even begin to keep up with it. I am going to add a couple more ottos but I can’t imagine how much difference they could make beyond the three that are already in it. I feed the 4 plattys once a day.

@Reply: You mean you have your lights on 24/7, and is yes it is not a good idea. Both plants and fish need dark periods. In case of plants a part of photosynthesis takes place in dark. A period of 8-10 hrs of light is more than enough.



Posted by Harley B:
My ammonia spiked last night out of nowhere. … i lost a few. . Noticing lots of fin Rot because of this. Do they need a heater or no?
Did 25% change this morning. …what could have caused this? Seems semi frequent now. …

@Reply: Sounds like you don’t have a good load of beneficial bacteria. I’d suggest putting in an easy to maintain filter, something with lots of surface area for colonization, basically if it’s under 30 gallons I’m saying to use another HOB or a sponge filter. I have a penguin 400 that works well too.

@Reply: I have a canister filter, as well as an internal filter with powerhead, and a uv filter as well.

@Reply: How much bio-media in your canister? That’s really weird!! If the colony is large enough there shouldn’t be any ammonia to speak of. Do you turn your filter off for any amount of time ever?

@Reply: All 3 filters run constant. Should they have an air pump in the tank?
The ph was acidic level, so that’s why im guessing ammonia. it’ll get better for a day then spike and i lose more. ..i don’t know what to do any more.



Posted by Jamie B:
Got a fish with a sunken stomach. Is metronidazole your first weapon of choice? And if so which brand do you use ;where do you buy it. If not what your first go tobforba sunken stomach?

@Reply: Personally, parasite sniper is superior. The whole reason for me to create the product was just because of the issue that several different treatment would address one parasite but not another. I wanted something that went after everything. As well as has a purging agent so you dont need to use epsom. Parasite sniper is what we ended up with. There is a video on it in my videos.



Posted by Kevin B:
What are these clear white worms in my newly set up tank?

@Reply: Get aquarium salt ASAP get rid of all your gravel or sand or your fish will get really sick. The worms hide in the filter and sand/gravel.

@Reply: Water hose contains these worms…you have water that settles and these worms grow… I have no clue what they are, but I lost my fish for cheating on my water change.

@Reply: google it…..they come from uneatin food….will not harm the fish….but live in the gravel……just google PLANARIA…..will tell you more about it.

@Reply: Planaria, harmless but an eyesore. Cut back on feeding, even skip a day or 2. Pretty common in heavily stocked heavily fed breeding setups, I ignore them when I get them, they eventually go away. They have nothing to do with a hose, and salt will cause much more harm to the fish than planaria will.

@Reply: I’ve had a tank cycled and setup for 2 years. Every now and then I get a burst of these tiny wiggly worms. After a short time they vanish, or my fish snack on them.
Just this last week I had them show up again, oddly enough I just added new live plants from petco.

@Reply: I had them also don’t panic they are harmless and BTW salt will not get rid of them just do a good clean and cut back on food your fish will do the rest mine ate them its normal.



Posted by Nathan E:
Do i really need 4 bio-wheels on my aquairum??? This is a 60 gallon tank?

@Reply: I have a 60 gallon its always good to over size your pump I had a 100 gallon pump no problems at all I broke my pump now I have two 30 gallon pumps I clean my tank every 2 weeks.

@Reply: You could, but if you want to cut wattage, I’d recommend using one, and then add sponge filters powered by an air pump.

Average HOB=115watts

Average air pump= 3watts.

@Reply: I used 2 of them before switching to canister filters, using 2 has many benefits, you can change or clean out the filter pads on 1 then the other at a different time, keeps a good colony of beneficial bacteria working at all times.

@Reply: Depends on stock and type of fish you want, if your keeping slow swimming fish that like calm waters and cant handle high flow then its probably not a good idea is it?

If one has good flow and your not going to overstock the tank then one is probably enough.

@Reply: or drop a bag of puregen and carbon in one if clear water is what your after, what other people have on their tanks has no correlation to what you should do it’s dependant on the fish your keeping the amount that’s it, for instance if you wanted to keep blackwater species 100 of those filters wouldn’t give you crystal clear water, carbon will remove tannins purgen will remove tiny particals and any filter polishing pad in any filter will give you clear water lol



Posted by Nathan H:
Fish aquariums are a cool addition to any room and that’s simple to see. Setting them up can sometimes be pretty confusing if you don’t do a little research before hand. I’m a real simple person and find that most writers make things ‘more complicated’ then they have to be. Today’s guide is devoted to the “Average Joe” in a sense of how simple and straight forward this guide will be on how to setup a fish aquarium.


Posted by Jaime B:
One huge variable that I want to mention is that “patience” is an important aspect to starting up a fish tank. The #1 reason why fish aquariums fail is because people do not do proper research and JUMP into throwing new fish into an aquarium and they die. Be aware that the setup of an aquarium is equivalent to an ecosystem.


Posted by Kelly E:
Before you start setting up your aquarium its important to keep in mind that some places in the house are better than other for keeping fish. When choosing a spot you don’t want to expose the fish to too much light nor too much darkness. Don’t place your tank in direct sunlight such as in front of a window, instead put the tank in room thats well lit by the sun, away from the direct sunlight.


Posted by Leroy Q:
If this is your first aquarium your best bet will be to start with a rectangular tank as opposed to a round, hexagonal, or octagonal tank, because they are by far the easiest to clean and also give you the best view of your fish. Deep tanks are harder to clean as well, and if you’re uneasy about submerging your arm in the water, than the more shallow the tank the better. When it comes to size you’ll have to figure out how many fish you plan on having. To determine what size aquarium is right for you see my article about how many fish can be put in an aquarium.


Posted by Megan B:
Yeah, yeah, I know. The saltwater/marine fish you saw the other day were a lot more vibrant than those boring freshwater fish. I’d love to take care of saltwater fish too, but they are leaps and bounds more difficult to take care of. Heck I’ve had freshwater fish for 5+ years and have even worked in the fish section at a pet store and I still don’t feel confident that I can care for them properly. There are 2 major groups of freshwater fish. Goldfish and Tropical. Both types of fish tend to be very non-aggressive and for the most part can go with any other fish that fall into their category of goldfish or tropical, but saltwater fish are often times very aggressive and need much larger tanks.


Posted by Brandon U:
While both fresh and saltwater fish can be very healthy and resilient if taken care of properly, you’re going to have to worry about a lot less disease and chemical imbalances when working with freshwater fish.
Ah I almost forgot to mention that saltwater fish are EXTREMELY expensive compared to most freshwater fish. God forbid you lose a fish or two, you’ll still be content that you only paid $1.99 for your guppy
Unfortunately new aquarium hobbyists are bound to make mistakes when setting up and caring for their first aquarium. Hopefully this article will help reduce the number of mistakes.