Can Goldfish Eat Bloodworms?

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As an omnivorous fish, goldfish will consume a variety of foods which means that they’re pretty easy to satisfy. Bloodworms are very much the Holy Grail when it comes to fish food. They are packed with protein and iron and are palatable and easy to consume. It’s no wonder that most, if not all, tank fish consume them relentlessly.

But do goldfish eat them? Yes, they do. Bloodworms are among goldfish’s favorite foods, and they would eat them as frequently as possible. And they do in the wild because that type of food is much of a delicacy for goldfish.

In captivity, however, things change a bit since bloodworms can be made available at all times. This is where the question comes in – how many bloodworms should the goldfish eat daily or weekly? And are there any health risks associated with their consumption?

Let’s check it out!

Are Bloodworms Safe for Goldfish?

For the most part, yes, bloodworms are safe for goldfish. However, the reality might not be so simple. In some cases, bloodworms can actually become a detriment to your fish’s diet. Wild-caught bloodworms pose various health risks since they can contain deadly bacteria and viruses that will transmit to the fish.

Feeding your goldfish too many bloodworms too often isn’t a good idea either. That’s because, although they are packed with protein, bloodworms lack a variety of nutrients, vitamins, and minerals that the fish needs. So, always make the bloodworm part of a stable and diverse diet instead of using it as main source of food.

Benefits of Bloodworms for Goldfish

Feeding bloodworms to your goldfish comes with a variety of benefits, such as:

  • Optimizing protein intake – Goldfish are omnivorous fish, so they require plant-based nutrients and animal protein via a diverse and balanced diet. Bloodworms are perfect in this sense since they contain a lot of protein, fats, and iron. They will complement the fish’s diet quite nicely when used in a well-rounded diet.
  • Tickling the goldfish’s predatorial instincts – The goldfish isn’t much of a predator, but it is an omnivorous fish, after all. So, it does like to eat live food which will hunt actively whenever possible. Throwing some live bloodworms into the tank will help the goldfish exercise its hunting capabilities a bit. This will keep the fish active and more energetic from one meal to the next.
  • Good for breeding – This may sound awkward, but it’s true. Feeding your goldfish bloodworms may actually instigate the fish’s breeding senses. This is all due to the goldfish’s natural conditions in the wild. Goldfish typically mate during late spring and early summer, when their environment is generally full with insects, larvae, and worms. They do so because the abundance of food will ensure the fry’s survival rates.
  • Adds variety – While all goldfish are omnivorous, they also have different personalities and preferences. Some might eat certain foods, while others will avoid them. Bloodworms are a safety-net-type food since all goldfish will eat them, no matter how fussy they are about their culinary preferences.

As you can see, there are a handful of benefits to bloodworms, provided you’re also mindful of the risks. And we’ll discuss these in the following section.

Risks of Bloodworms for Goldfish

While they are extremely nutritious, bloodworms also carry some risks with them. These include:

  • Nutritional deficiencies – Bloodworms are a good source of protein, fat, and iron, but not much else. Fish love them since they’re also palatable, which leads some people to feed them more bloodworms more frequently than they should. This will ultimately cause the fish to experience nutritional deficiencies, which can be deadly in some cases.
  • Too much fat – Bloodworms are rich in protein and fat, so they’re best consumed in moderate portions. Too much fat and not enough fiber will constipate the fish fast. Constipation is dangerous in fish since the clogged and swollen abdomen will press against their bladder, increasing the risk of swim bladder disease. Simply put, this condition will affect the fish’s buoyancy and swimming capabilities, potentially causing the goldfish to drown.
  • Risk of parasites – This isn’t a problem with store-bought bloodworms since those are relatively safe. However, some aquarists get their bloodworms from unsafe sources, including straight from the wild. This is a mistake since these bloodworms are generally packed with bacteria and parasites that will transmit to your fish.

You can prevent all these issues by getting your bloodworms from reliable sources. We’ll discuss this aspect next.

Sourcing Bloodworms for Goldfish

There are 3 types of bloodworms, based on their state that you can use for your goldfish:

– Frozen Bloodworms

These are available in most fish shops and usually come in the form of cubes. These are basically conglomerates of bloodworms packed together in a compact form. You can throw the cubes directly into the fish tank and allow the goldfish to nip on them gradually. You can also break the worms into smaller chunks to help the fish eat the easier.

One thing’s for certain – frozen bloodworms are a great option if you don’t want to go shopping too often. Simply place them in your freezer and feed your fish small portions whenever necessary.

– Freeze Dried Bloodworms

Freeze-dried bloodworms are even more long-lasting than frozen ones. The difference between the 2 is that freeze-dried bloodworms contain fewer nutrients. That’s due to the preparation process, which includes extracting the fluids from the bloodworm.

This procedure is necessary to prolong the tissue’s lifespan. As a result, freeze-dried bloodworms can remain a viable food source for months or even years when stored properly.

However, there are 2 downsides worthy of mentioning:

  1. Less nutritional value – I advise soaking the freeze-dried bloodworms in a vitamin complex to increase their nutritional value. Or use them as an ingredient in nutritious homemade paste that you can freeze for later use.
  2. Soaking is necessary – Freeze-dried bloodworms are like rubber. Your fish won’t be able to eat them in their ‘natural’ state. So, you need to soak them for about 10 minutes in tank water for the fish to consume them easier.

Other than that, freeze-dried bloodworms are a great long-term food for your goldfish.

– Live Bloodworm Culture

I rate these as the most nutritious bloodworms you can find. They represent one of the goldfish’s natural foods and are filled with ready-to-eat protein in a natural state. Your goldfish will favor live bloodworms over any other food, if available.

The obvious problem is that they’re not fit for long-term storage. This is where live cultures come into play. I recommend live cultures to all aquarists since these provide the fish with fresh, ready-to-eat food to ensure optimal nutrient intake. Plus, your fish loves live food that they can chase and hunt.

Sure, you will need to consider a certain investment at first since you require some equipment to get things going. Fortunately, bloodworms don’t require too much care or a lot of space, for that matter. A 50 by 25-inch plastic container with a 6-inch-deep substrate of garden soil can house close to 100 bloodworms, each capable of growing up to 14 inches.

They are far easier to maintain than feeder fish or crustaceans and a lot less messy. You can use the live bloodworms however you please. You can either feed them in their live state, freeze them for later use, or use them as ingredients in homemade food paste for your fish.

How to Feed Bloodworms to Goldfish?

You can simply throw a couple of them in the tank and witness the goldfish devouring them. If the bloodworm is too large compared to your goldfish’s size, break it into smaller pieces.

If you want to store your bloodworms for later use, I recommend either freezing them or using them as ingredients for various food recipes. Mix them with other protein sources and veggies, and you’ll obtain nutritious and delicious foods (by fish standards) that your goldfish will thoroughly enjoy.


Bloodworms are highly nutritious, but you should use them moderately. They have a lot of protein but not enough of other vitamins and minerals that are vital to your goldfish’s wellbeing.

Set up a bloodworm culture and use them to complement your goldfish’s diet long-term. The benefits will make the trouble of setting up and maintaining the live culture worth it.


Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.
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