Oscar Fish, What to Feed Them

From the previous article we know that Oscars can reach up to 18 inches and with up to 3 ½ pounds. They are territorial, aggressive, and so tank mates are not really suggested unless they come from the same species (cichlid). There are over 10 varieties of Oscar fish, due to cross breeding. They are all stunning to look at and would make a great focal point in your home. Oscars are omnivorous, so exactly what can/do you feed them?

Since Oscars are omnivores, there are many different things that you can feed them. You have feeder fish; guppies, mollies, minnows, and others. But you do want to be careful because any fish that  you bring home from a pet store can have a disease and you wouldn’t know. You can also feed your Oscar live, frozen, or dried; blood worms, brine shrimp, grasshoppers, and more.

We are going to go in depth on what you should feed your Oscars, as they need a very nutritious diet. We discuss their habits in the wild, in an aquarium, and how to care for and feed your Oscar. Not everyone is going to buy an adult, full grown Oscar as a pet, so we will cover the baby stuff as well.

Babies Oscar to Adults

I, personally, would choose to purchase a baby Oscar over a full grown adult. I would love the opportunity to raise an Oscar and watch them develop as I have with my children. They are very intelligent creatures and are said to eventually be able to recognize their caretakers/owners. Wouldn’t it be wonderful to watch them play and interact with you from the beginning stages of their life?

Oscar babies are just as small as any other tropical fish, 1-2 inches in length. If you have the perfect aquarium set-up, food, and care then your baby Oscar should grow approximately 1 inch a month. This means, in 10-18 months you will have a full grown, adult Oscar.

Oscars require a very nutritious diet, whether they are babies or full grown. So you will not need to do any type of food adjustments or changes, except for the amount of feedings, as they grow. Making sure they have the proper food will ensure that they do not get any illnesses or disease, unless brought in from an outside source.

No matter if they are babies or adults they also need the best filtration system that your pocket book can handle. Their water needs to be very clean. With bigger fish comes a lot more waste. We are going to cover a little about filters later on.

Diet of Oscar Fish

You want to make sure you have a variety of nutritional food for your Oscar. Including what they like to feed on when they are in the wild. They are native to the Amazon. In their natural habitat they eat a lot of insects. So providing them with live crickets, grasshoppers, mealworms, nightcrawlers, and locusts is going to keep them very happy and aid in keeping them healthy because of the vitamins.

Seafood is also a wonderful supplement for your Oscar. They enjoy cockles and mussels (freshly shelled). Their favorites are prawns and shrimp. They are a good source of fiber for your fish and will aid in keeping their digestive system healthy. You also give them cut up pieces of squid, tuna, and salmon.

The following is a shortlist of other foods that are very healthy for the Oscar and that they enjoy eating:
  • Pellet Food: Hikari Cichlid Staple, Cichlid Gold, and Cichlid Excel. There are all available in mini, medium, and large pellet sizes. Making it easy to stay consistent as your Oscar grows.
  • Frozen Food: Hikari Krill, frozen blood, fresh shelled cockles, mussels, and Sally’s Frozen Emerald Entree
  • Live Food: nightcrawlers, beetles, super worms, shrimp (but best if frozen), and fish. But as we stated earlier, beware with fish because of disease that you can not see.
  • Fresh Food: squid, salmon, and scallops. Frozen salmon will work as well.
  • Other Foods: peas, green beans, banana, strawberry, and canned JurassiDiet Easy-cricket, Easy-worm, and Easy-pillar.

How Much and How Often Should Oscar Fish Eat

Baby Oscars, as with most babies, always seem to be hungry. But, even as babies you have to make sure how much you feed them because you do not want to overdo it. 

It is suggested, and basic common sense, to feed your baby Oscar small foods. They are very greedy and like to get as much into their mouth as possible. Larger foods or pellets will produce problems in them being able to swallow.

The Cichlid pellets, as stated above, come in different sizes.  So, of course, you want to start out with the smaller pellets as babies, and you can increase the pellet size as the Oscar gets bigger. You want to drop a few pellets in at a time for 3 minutes.

Anything after that 3-minute mark that they have not eaten, you need to remove from the tank. This will aid in keeping the water clean and healthy. You need to do this 3 times a day until they reach approximately 5 inches long.

Once they reach between 5-6 inches long, you can get the medium sized pellets, and cut their feedings back to twice a day. You want to continue with the way you were feeding them as babies, dropping just a few pellets at a time for approximately 3 minutes.

I would guess that a few would be 5-7 maybe. You don’t want to put too much in at once, but you also don’t want to just give them 1-3 at a time, because that wouldn’t be enough. At this stage you will begin to get used to their feeding habits; about how much they are going to eat in that 3-4 minute time frame and how they are going to let you know that they are full.

When your Oscar reaches 10+ inches, you want to cut their feedings down to once a day and you can begin giving them the large pellets, and the live, frozen, and fresh foods that we mentioned above. Again, take it slow, until you get used to how much they are actually going to eat at their feeding. Anything that they do not eat within 5 minutes maximum, remove from the tank immediately to avoid toxins building up. 

Oscar Fish Illness

Let’s talk a little bit about fish illnesses. If you don’t keep the tank clean, feed your fish properly, and follow other care guidelines then your Oscar (any fish for that matter) could get ill, a disease, or even pass away. With the Oscar you have to be careful with the feeder fish.

Not only do you not want to overstock the tank with them, but you have to observe them extremely closely in the pet store before you bring them home. If anything looks “off” then do not purchase them. You don’t want to talk about the risk of infecting your fish.

The leading cause of death in fish, no matter what species, is toxic ammonia. This will normally happen in an aquarium that is in the process of cycling. That is why it is recommended that you do not put any fish in the tank until the cycling process is fully complete, and you have checked your pH and other levels. But it also doesn’t take a lot to upset the balance of the biological filter.

This will also cause toxic levels of ammonia to build up in the water. You will not notice this right away unless you are meticulous at checking your chemical balance in your aquarium on a very regular basis.

Ammonia Poisoning/Stress

Here are a few symptoms/signs that your fish could be dealing with high levels of ammonia in their water:
  • Loss of appetite
  • Inflamed gills
  • Lethargic
  • Popeye disease (inflamed eyes)
  • Gasping for air

Your Oscar may not show any signs until the ammonia level is extremely high. Keep an eye on your pH levels, as these will indicate how toxic the ammonia is. Having a low pH is very beneficial to your fish. An alkaline pH will definitely make the ammonia more toxic. Try to keep your pH level in your aquarium at a 7.0 or lower. 

Nitrite Poisoning

Nitrite is a by-product of ammonia. It can be almost as toxic to an Oscar and the signs and symptoms will be consistently the same. If you are having problems with ammonia in your aquarium then it won’t be long and you will probably see a spike in your nitrite.

Nitrite spikes sometimes occur when too many fish are introduced at once. This shouldn’t happen with your Oscar tank, unless you add too many feeder fish at once, because you will only have 1 maybe 2 Oscars in one tank. 

3 Oscar Fish Biggest Causes of Illness

Fungal Infection: some of your Oscars symptoms may be; scratching, cotton-like substance on their skin, darting back and forth for no reason, or swimming erratically.
Bacterial Infection: your Oscar may be lethargic, bloated, bulging eyes, loss of color, open sores, or red streaks throughout their body.
Parasitic Infection: symptoms of this kind of infection are; excess mucus, slime on the body, white spots, breathing heavy, visible worms, or scratching on a piece of wood or rock.

Best Tank Set-Up for Oscar Fish; Filter, Heater, Lights, and More

It is very important, before you purchase an Oscar, that you make sure you are totally committed and up for the task. These fish can live 10+ years and they rely solely on you for their care and companionship, just as a dog or a cat would. Especially if you purchase them as a baby. 

You will have to be able to commit at least 1 hour a week to the maintenance and cleaning of your Oscar tank. As long as they are living, you need to be there for all of their needs. You definitely do not want to put off or ignore this task, as it can cause damage to your fish. It is extremely important that you do this once a week. 


Video from Black Hawkmos YT Channel

This is going to cost money; the lighting, the heater, and the filtration system. It will all use some electricity. The lighting and the filter not so much. But if you have a 55 gallon aquarium you are going to use approximately 200W of heating. Your filter has to be kept on 24/7, but still doesn’t use much electricity and your lights you only want to have on 12 hours per day, maximum. 

You also have to factor in food, your testing strip kit, and any medications you may need. Plus, the decorations for the tank; fine-grained sand, bogwood, rocks, plants, etc. Some of those items will not be overly expensive. The main hit on your wallet is going to be the tank itself and the filtration system. Everything else is not too bad at all.

As stated in our other article on Oscars you want a minimum 55 gallon tank for 1 Oscar. As I stated before, I prefer to go up to a 75 gallon tank to make sure they have plenty of room for the decor and still be able to have ample room to be comfortable and swim around. 

You want to make sure you have a very secure and sturdy hood on your tank. Oscars like jumping and a sturdy tank hood will keep your Oscar where he belongs, instead of on the living room floor.

Filtration For Your Oscar Fish

Your filtration system is the heart of your tank, the life-line for your Oscar. The filtration system cleans out most of the harmful things that will hurt your fish. You need to have a filtration system that will move the water quickly to remove the toxins.

For example; if you have a 50-70 gallon tank it is suggested that you get a filter that can move 100+ gallons of water per hour. This guarantees that the toxins are being removed from the tank in a timely fashion.

What Is the Best Filter

For an Oscar, you only have 2 filter options. This is because they are bigger fish and bigger fish cause more waste. A filter that you use for a goldfish or betta tank is not going to be near powerful enough to keep up in an Oscar tank.

You can choose between a canister, which is highly recommended, or a sump filter. In our previous article, we touched on a Fluval filtration system that could pump 400 gallons of water per hour. Yes, that is probably overkilled for a 100 or 125-gallon tank, but Fluval also offers smaller filtration systems that work just as well as the bigger one.

 Another highly recommended brand of filtration system is the Eheim. These are a little bit more expensive, as they are higher rated than the Fluval, but they are well worth the extra money if you are serious about keeping your tank as clean as possible and your fish healthy and happy. These are considered the Corvette/Royals Royce of canister filters. 

The Heater

Oscars are tropical fish, so you will need to keep their tank between 77 and 80 degrees at all times. I am recommending a heavy duty or even metal heater because an Oscar can get very destructive, when stressed, and sometimes for no apparent reason.

There is a titanium heater on the market that is up to 500 watts and heats a 125-gallon tank perfectly. It is made by Aqua Medic. This will be quite an expensive heater, as you have to purchase the control box separately, but they are indestructible. There is also a line of heaters called SCHEGO. These are also made of titanium, but they are more affordable.

As for thermometers, it is pointless to put one in the tank, because the Oscar will destroy them within minutes. Just keep a good one on hand so that you can check the temperature every once in a while. 

There is also no special lighting that is required for Oscars. Just remember, do not leave them on all day every day. In the wild, Oscars get used day and night. You don’t want your aquarium to be any different. You want to mimic their natural habitat as much as possible when you are setting up their home inside a home. Set your lights for every 12 hours if that will make it easier.

Remember to also have at least 2 caves in your aquarium for your Oscar to ‘hide’ in. They enjoy their solitude and love to hide out in caves.


Between our 2 articles on Oscar fish, you should know everything you need to know to have an Oscar fish. We have explained tanks, filtration, heaters, decorations, disease, feeding, and so much more. Just remember, Oscars are almost a lifelong commitment.

At least 10 years of your life, if not more. So do our homework and make sure that you want to take on the task of having an Oscar. I think you will fully enjoy Oscar and their beauty once you have them in your home. 


I'm passionate about fish pets and love sharing everything I learn about them.

Recent Posts