Do Oscar Fish Eat Worms? (Earthworms, Mealworms, Bloodworms & More)

Do Oscar Fish Eat Worms blog banner

Oscar fish are omnivores and voracious eaters in the wild and although worms don’t tend to be a staple food in nature, they will readily consume as much of them as they are fed in an aquarium.

But which kind and how many? That’s what we’ll discuss in this article in detail.

Naturally, Oscar fish will eat anything that fits in their mouth and is tasty, including vegetables, frozen food and live food like feeder fish and worms.

In one bite, a 3-inch worm will go down the belly of the Oscar fish.

Worms are not the typical food that the wild Oscars would eat, (feeder fish are more of a staple food) but if you have them confined in a fish tank, then you can introduce worms to their diet.

Worms make for a good source of protein, fat, and fiber for the Oscar fish.

You can give them a moderate supply of worms from species including:

  • Earthworms
  • Mealworms
  • Superworms
  • Waxworms
  • Bloodworms

Though each of these worms have their pros and cons (more on this later in the article), they shouldn’t be given in excess to prevent an unbalanced diet.

When the Oscar fish gets addicted to eating worms, they won’t eat fish food (like their flakes or pellets) with as much enthusiasm as before.

That’s one situation you won’t want to experience as these fish need a varied diet where worms should not make up more than around 10-20% of an Oscar’s diet.

More so, you should endeavor to investigate where the worms you’re feeding your oscar fish come from.

This is because using worms gotten from soil where fertilizers or pesticides have previously been used is inviting harmful chemicals into your fish tank and it wouldn’t only ruin the aquarium water but will have severe effects on the oscar fish.

So, when looking to get worms for your oscar fish, check with a local fish store near you to get suitable ones.

Can Oscar Fish Eat Worms?

Yes, oscar fish can eat worms and in this section, we’ll take a look at the 5 common worm species that they’ll happily digest. Enjoy reading!

Which Worms Should I Feed My Oscar Fish? 5 Types

Oscars are tropical fish that come from the rivers and streams of South America and are not native eaters of worms.

But, if you have them in your tank, they can quickly acquire a taste for them and become avid eaters of worms.

The recommended worms to feed your oscar include:

  1. Mealworms
  2. Earthworms
  3. Waxworms
  4. Bloodworms
  5. Super worms

Let’s discuss in more detail the pros and cons of each of these live worms:

NOTE: These slimy yummies should be fed to your Oscar in moderate portions (how many of each type of worm exactly is discussed further in the article) because they can get addicted to the taste and decide to stop eating other food that is a staple in their diet.

Can Oscar Fish Eat Mealworms?

Mealworms are suitable for feeding Oscars.

They are tasty, crunchy, and delicious to a greedy oscar, so you should consider adding them to your Oscars diet in moderation.

You can serve mealworms coupled with insects, crickets, and other foods.

Moreover, you shouldn’t overfeed your Oscar mealworms because they contain a lot of fat and can lead to abdominal discomfort, a poor digestive system as well as fatty liver disease.

Not something that oscar owners want to deal with after feeding them too many meal worms.

You can also perform something called “gut loading” (overfeed them) on meal worms if you want to make them larger for your large fish.

Can Oscar Fish Eat Superworms?

In quick successions, the oscar fish will eat a couple of Superworms and still want more.

Tasty and mouthful, the Superworms will provide all the nutrients needed for the oscar fish to grow faster and stronger.

Instead of feeding crickets to your Oscar, provide a small amount of Superworms (exact amounts a bit further down).

One Superworm packs more protein than you’ll find in 20 crickets.

As noted with feeding live food to Oscars, you MUST not overfeed them.

The cons of superworms during feeding time is that some have owners have reported dropping live worms in the tank can mean superworms will bite or sometimes even eat through an oscar’s stomach if the head hasn’t been crushed by the oscar.

It’s rare but to avoid this risk, you can crush each superworm’s head before dropping it into your tank.

Can Oscar Fish Eat Earthworms?

Earthworms are a yes-yes for oscar fish as they contain vitamins, protein, zinc, copper, minerals, and nutrition which are needed for optimal, strong growth.

Earthworms MUST be cleaned thoroughly before they’re introduced to the feeding schedule of a fish tank so that they do not contaminate the water or be of harm to the oscar fish and other fish.

Again, earthworms should be fed in moderation and make up about only 10-20% of an oscar’s diet.

Do Oscar Fish Eat Worms blog post image

Can Oscar Fish Eat Blood worms?

Oscars eat bloodworms and find them rather delicious.

What sells the bloodworm away is its attractive color – they are vividly red and that attracts the oscar fish to eat this delightful treat.

Oscar fish will eat bloodworms as live foods, frozen foods or even dried. This makes them a convenient snack for you too.

Bloodworms are high in protein which is a benefit.

Live bloodworms are more nutritious but carry extra contamination risk and are harder to find than frozen and dried varieties.

Like every worm you want to introduce into your fish tank, you must wash the bloodworms to avoid issues like your oscar getting sick.

Warning: Do not overfeed your oscar fish with worms in a bid to make it grow faster.

Indiscriminate worm feeding will result in addiction and in worst cases, intestinal issues like constipation.

Are Worms Healthy For Oscar Fish?

Yes, worms can be healthy for Oscar fish in moderation but unhealthy for them if they regularly replace typical aquarium oscar fish food like their flakes and pellets.

Worms are packed with the wholesome goodness of nutrients including:

  • fat
  • fiber
  • vitamins
  • protein
  • zinc
  • copper
  • minerals

These nutrients contained in worms make them healthy to use as oscar fish live food.

When are Worms Unhealthy For Oscar Fish?

You shouldn’t feed worms in isolation of other fish food, so that they can maintain a balanced diet.

However, everything that has its advantages also has its downsides.

The reasons why worms aren’t suitable and healthy for Oscars include:

Worms Can Cause Addiction and Fussy Eating

One of the biggest dangers here, which you’d probably not even consider, is that Oscars can be fussy with their food just like us!

Live foods like worms really get their taste buds going and you may be surprised to see your Oscars start to decline its own food (cichlid food like flakes and pellets or homemade food like peas) in preference for live food.

This deprives them of essential nutrients from a healthy diet.


Following on from the above point, indiscriminate feeding of worms can cause your Oscars to be constipated. Especially if they are now fussy about eating food with fibre.

This could even lead to their death if you don’t feed vegetables like peas to your oscar or get them to eat plant matter.

This becomes much harder if they have become fussy eaters.

Excess Worms Can Make Your Aquarium Dirty

Worm casting in your aquarium contributes to waste and the eventual sickness of your Oscar worms.

Adding worms to your tank to be eaten by your Oscars will lead to a messy situation, making them unhealthy.

The castings can be useful in the soil but not in the aquarium.

May Absorb Unhealthy Chemicals, Toxins & pollutants (myth?)

While it’s true that worms are capable of absorbing the contaminants they come into contact with in their environment, this generally doesn’t cause them or other freshwater fish that eat them any problems.

Why? Worms are very good at neutralizing any toxic chemicals they absorb according to a peer-reviewed journal.

Worms that have come in contact with pesticides, pollution, and hazardous chemicals will generally kill them off once inside them and should not be a health concern for your Oscars.

If you still have concerns about earthworms you find in your garden and still want to feed live food like worms, get them from a reputable local pet store as they’re most likely to have not been in contact with toxic chemicals in their closed environment.

Where Can I Get Worms For Oscar Fish?

You can get worms for your Oscar fish in your garden, from soil or by purchasing either from an online store, your local pet shop or a local fish shopnear you.

How Many Worms Should I Feed My Oscar Fish?

The ultimate question.

If you have fully grown adult Oscar fish, then feed them 1 time every other day.

But how much of that should consist of worms?

Unfortunately, there is no 100% strict answer to this question, as much of a cop-out as it sounds.

You’ll hear of many different experiences from different owners.

Some successfully feed their oscar worms once a day.

Others will feed them worms once every five days or more.

Ultimately, it will depend on the variety of protein containing foods available to you to feed them.

If you have many different varieties of meaty foods like brine shrimp, beef heart etc that you feed your oscar, then it makes sense to rotate worms every few days rather than every single day.

Bloodworms are not suitable for adult oscars, not because they won’t eat them but because the uneaten food or their voracious eating habits may cause a mess in your tank.

Stick to larger feed for them. Other worm types are fine.

With fully grown Oscar’s, their voracious appetite means it is difficult to tell when they’ve had enough.

Just because they’re still eating DOES NOT mean you aren’t overfeeding them.

TIP: While fully grown oscars can go up to 5 days without food, it’s not recommended especially if adult oscars are sharing a tank with other fish. They could be on the receiving end of a starving Oscar who won’t be in a merciful mood.

How Many Worms Should Juvenile Oscar Fish Eat?

As for the juvenile Oscars, they need to be fed about twice a day, even up to three times every day (but not strictly worms).

You can feed them worms more often but the same rules apply.

Keep it balanced and avoid feeding them 100% meaty food.

Don’t overfeed them worms to avoid constipation and definitely avoid feeder fish due to potential parasites and small fish may struggle to eat feeder fish.

A great indicator that baby oscars have had enough food is to watch for slight distention in their belly.

That usually means they’ve had enough.

Bloodworms are suitable here, as are small varieties of the other worm types, but larger nightcrawlers may be too big for smaller fish and may require cutting into smaller pieces.

Other Foods Oscar’s Eat Besides Worms

  • Pellets and flakes (pellets are preferable as they create less mess and water pollution)
  • Live insects like crickets (or freeze dried)
  • Ghost shrimp
  • Nuts and tropical nuts
  • Fruits
  • Vegetables (like peas)
  • Seafood (shrimps, scallops, squid)

Foods to Avoid or Feed in Moderation For Your Oscar

Oscar’s are predatory omnivores, so many experienced owners like to feed feeder fish like rosy red minnows and goldfish.

While you can do this successfully, it’s risky as many farm-raised fish like goldfish may carry diseases which can be transferred to your oscar.

While many breeders have got better at raising them in the proper conditions, I’d avoid feeding goldfish as the risk is still there.

If you still want to feed goldfish to your oscar, be sure you trust the source and maybe even consider raising your own feeders in controlled conditions.

Summary & Final Thoughts

Oscar fish are avid eaters of worms, even though they aren’t a staple for them in the wild and they eat a wide variety of them including mealworms, earthworms, Superworms, waxworms, and bloodworms, among others.

This article has talked about the feeding habit of Oscar’s in relation to their ability to eat worms and whether they are healthy or not.