What Are Blood Worms? (Everything You Need To Know)

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You’ve probably heard of bloodworms if you’re a fishkeeper, and who knows, you might even have some in your own freezer of fish cabinet. But do you know where they come from and if they are good for your fish? In this article we will dive into the facts explain what are blood worms, what they turn into, and teach you all about these fishy treats.

Here we go!

Key Takeaways

  • Feed fresh and saltwater fish bloodworms as a tasty treat
  • freshwater bloodworms are small creatures used as fish food but marine bloodworms are more popular for fishing bait.
  • Use frozen and freeze-dried bloodworms as a supplement but not a primary food source for your fish
  • Wear gloves if you’re going to be handling bloodworms a lot because some people are allergic. It’s a good idea to wash your hands too!
  • Adding live bloodworms to your tank has the small risk of introducing parasites and other unwanted organisms

So What Are Blood Worms?

There are different creatures called bloodworms and this can be confusing for newcomers to the fishkeeping hobby.

Aquarium bloodworms are the baby (larval) stage of small mosquito like flies called midges. These tiny worms are called bloodworms because they are red, not because they drink blood! Aquarium bloodworms are less than half an inch long.

Much larger worms dwell along sandy and muddy shores in marine environments and they are also called bloodworms. These huge worms are the ultimate fish bait and most saltwater fish go crazy for them!

Marine bloodworms aren’t used a lot in the aquarium hobby though, so we’ll be talking about the small freshwater midge larvae from now on.

So why are they red?

Bloodworms get their bright red color from the hemoglobin in their body – that’s the same stuff that makes our blood red by the way. Vertebrate animals like mammals, birds, reptiles, and frogs all have red blood, but its actually pretty unusual for an invertebrate.

Are you wondering why their blood is red? Well, these worms live in a world with low oxygen (anoxic environment) and the hemoglobin helps them breathe!

Life Cycle

Bloodworms and midge flies have a pretty complicated life cycle and the worm we feed or fish is just one of them! Read on to learn more about each stage of their biology.


Midges are tiny flying insects that you might see swarming around near lakes and ponds. These guys are harmless except for being a little annoying when they fly around lights at night. Midges might look like mosquitos but they are actually vegetarians.

Midge Fly

The midge fly has a very short lifespan of just a few days. In this stage they must mate and find some freshwater to lay their eggs.


The adult flies lay their eggs on the water’s surface in a gelatinous mass. These tiny eggs sink to the bottom and hatch after a just few days.


Group of Bloodworms

The newly hatched larvae feed on organic material in the water and live in tubes of fine sediment or burrow into the substrate. These larvae are the bloodworms that we feed our fish, and they become redder as they grow.


Bloodworms live for several weeks, depending on the water temperature, and eventually change (metamorphose) into pupae. These pupae move up to the water surface and pupate into adult midge flies, ready to start their life cycle all over again!

Where do they live?

Blood worms are extremely common creatures in pretty much any freshwater environment. You can find them in freshwater ponds, rivers, lakes, and even gutters and buckets of rainwater. They can also live in very damp environments like wet soil.

Where can you get them?

You can purchase bloodworms online or from just about any fish-keeping store and many general pet stores too. Bloodworms are available in various forms, including frozen or freeze-dried packs. These worms are produced at a bloodworm farm.

Live bloodworms are harder to find but speak to your local fish store or other aquarists in your area to find out if anyone is breeding them. You can also breed your own bloodworms, and we’ll cover that topic a little later in this article.

What are they used for?

Bloodworms are used as a supplementary diet for freshwater fish. There’s a lot of contradictory information out there about whether you should feed your fish bloodworms or not, and this article isn’t going to tell you what you should and shouldn’t feed your fish. Instead, we’ll cover the basic facts you need to know to make an informed decision.

Bloodworms are an important natural food source for a huge variety of freshwater fish and other aquatic animals out in nature, so there’s no doubt that fish love bloodworms! These tiny creatures are a very important part of the aquatic food chain.

Let’s take a look at some of the benefits of this natural food source:


Bloodworms are a great food source for carnivorous and omnivorous fish. They are excellent for conditioning fish and can really bring out their colors. Bloodworms provide a natural, unprocessed food source, just like what your fish eat out in the wild, and fish just love hunting live bloodworms in their tank!

Nutritional Information

Bloodworms provide an iron-rich food source, but they contain loads of other important minerals and vitamins too, including essential amino acids, vitamins, and minerals. Bloodworms have the following approximate nutritional values from Omega One’s frozen blood worms package:

  • Protein: 8%
  • Fat: 1%
  • Fiber: 3-4%
  • Moisture: 82%

In contrast, freeze-dried bloodworms have more nutritional value. See Omega’s freeze-dried product below:

  • Protein: 40%
  • Fat: 3%
  • Fiber: 5%
  • Moisture: 7%
Omega One Freeze Fried Blood Worms

A great freeze dried product or tropical fish. Easy to supplement with vitamins

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Unfortunately, there are some downsides to feeding bloodworms too. Consider these facts before you feed bloodworms to your fish.

Frozen and freeze-dried bloodworms are great as a supplementary food source or an occasional treat, but they do not provide the complete nutrition of carefully formulated commercial-dried foods. You should not feed bloodworms every day as this may cause health problems like constipation.

Some people suffer from bloodworm allergies, especially those who feed them on a regular basis. Fish keepers report hypersensitivity to both frozen and freeze-dried bloodworms1.

Exposure to these creatures can cause skin irritation, asthma, and other unpleasant side effects. Use gloves and wash your hands after working with this food source if you think you might be allergic. You should also avoid inhaling the dust of freeze-dried bloodworms to avoid these issues.

Which Fish Eat Them?

Pretty much every popular aquarium fish will eat bloodworms! The only species that won’t eat bloodworms are true vegetarians like otocinclus catfish. Here are a few examples of aquarium fish that love bloodworms:


There are an estimated 20,000 midge species in the world and over 800 in North America alone, so there are a whole lot of different bloodworm types out there! What’s more important to us aquarists is the form they are in before we use them as fish food.

Let’s take a look at the best options for feeding your fish bloodworms.


Frozen bloodworms are the best choice for many aquarists because they provide a good compromise between convenience and quality.

Unlike live bloodworms, frozen bloodworms lose some of their nutrients because they expand and burst their cell walls. However, the major producers of bloodworms feed a highly nutritious diet before freezing to increase their nutrient levels, so they are still full of goodness for your fishy friends.

You can buy frozen bloodworm cubes in various sizes, and they are very easy to feed in your fish tank. Simply drop a cube into your tank and watch the fish enjoy this tasty treat as it quickly thaws.

However, there are many frozen bloodworms in a single cube, and sometimes you may need to split up a cube before adding it if you have just a few fish.

Another popular way of feeding frozen bloodworms is to thaw them out in a glass of tank water. You can then suck them up in a turkey baster and add them to your fish tank. The benefit of this method is that you can feed your fish directly and make sure each pet fish gets his or her fair share!


Freeze-dried bloodworms are the most convenient form of prepared bloodworms (and as we saw the most nutritious from the analysis earlier. They are super easy to use because you don’t need to thaw them, and you can control the amount you provide much easier.

Freeze-dried bloodworms also have the benefit of being cheaper than frozen worms, and they keep for much longer if you keep them cool and dry.

Some aquarists prefer to soak their freeze-dried bloodworm in water to soften them up. You can do this by adding them to a little tank water for a minute or so and then pouring it into your fish tank. You can enhance their value even further with vitamin dosing using an additive like Vita-Chem.

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Vita Chem

One of the best nutritional supplements you can use for freshwater fish. Works great with pellet and fried dried foods.

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If you gave your fish the option they would choose live bloodworms all day long. Live is the ultimate choice because the worms still contain all their nutrients and fish love hunting the wriggling worms.

One of the benefits of live worms is that you always know they are fresh. If you got them from a trusted source or raised them yourself then you’ll also know they don’t contain any toxic chemicals or nasty pesticides.

Adding any live creature to your tank comes with a small risk of introducing unwanted pests and diseases though, so think carefully first.

You can feed your fish live bloodworms by sucking them up in a turkey baster and then squeezing them out right in front of your fish. They will love it!

Raising Bloodworms

It is possible to grow your own bloodworms, and this may be your best option if you can’t source live bloodworms. However, growing live bloodworms takes a little more work, so this is not the easiest way to feed your aquarium fish. I supplied a video from Betta Guppy HAUS showing how to culture bloodworms. I’ll go into more detail below.

Let’s take a look at the basic steps.

  • Create a habitat

The simplest way of growing live bloodworms is to collect rainwater in a bucket and leave it out in the yard. Dust from the air, algae, and a few decaying leaves will create a natural food source for the bloodworms.

A clean white bucket is ideal because you will be able to see the bloodworms and their tunnels much easier. Make sure your container has not been used to store any dangerous chemicals that could harm the worms or your fish.

  • Give it time

You don’t need to buy bloodworm eggs to rear live worms for your fish. Adult midges will find the water and lay their gelatinous egg sacs all on their own! It could take just a few days or a week for the eggs to hatch, so check back regularly.

  • Harvesting

Harvesting fresh bloodworms is much easier in clear water. Simply grab a turkey baster and suck them up one by one. Mosquito larvae, daphnia, and cyclops are all great food sources that you might find in your bucket but avoid sucking up other creatures that could be harmful in your fish tank.

  • Cleaning

Once you have enough bloodworms, simply squeeze them out into a fine net like a brine shrimp net and run water through them to wash off any dirt. You can then put them in some tank water, and suck them back into your turkey baster to feed to your fish.

You can feed them live or freeze them yourself, which could have the benefit of killing other unwanted organisms and parasites.

Other Live & Frozen fish foods

Bloodworms are one of the most popular live/frozen fish foods, but they are not the only natural food source for freshwater and saltwater fish. Let’s check out a few other great options.

  • Brine shrimp

Pretty much any fish that eats bloodworms will love eating frozen or live brine shrimp too! These tiny crustaceans are available freeze-dried or as frozen blocks. You can also hatch and rear them yourself, and this is an amazing food source for fish fry and smaller fish species.

  • Ghost shrimp

Ghost shrimp are another great food source. Many medium size fish will happily eat them. For smaller fish, they can be good tankmates instead of food. Better functional shrimp and ornamental shrimp would include ones like cherry, and Amano shrimp.

  • Tubifex Worms

These tiny aquatic creatures appear similar to live bloodworms but have a very different larvae life cycle and are browner in color. They are available as freeze-dried and frozen food and can be fed to any fish that enjoy bloodworms.


Are bloodworms harmful to humans?

The freeze-dried, live, or frozen bloodworms used in the aquarium hobby can cause allergies in some people, although they have been used by fishkeepers for many years, and most people have no problems.

The worms used as fishing bait are much larger creatures that can give a painful bite if handled and that makes these bloodworms dangerous. When some bloodworms bite they inject a venom that can feel like a bee or wasp sting, so take care when handling these creatures!

What do blood worms turn into?

Bloodworms are the larval (baby) stage of midges, which are small, mosquito-like flies with fluffy feathery antennae. The adult midge fly does not bite or suck blood, although they do form swarms which can be a nuisance, especially around lights at night.

What is the purpose of blood worms?

Bloodworms are a vital component of a healthy aquatic ecosystem, and they provide a natural food source for fish and many other aquatic animals.

They are popular in the aquarium hobby because they provide a healthy varied diet and they can be very important for picky eaters that refuse prepared dried foods.

What do bloodworms eat?

The tiny bloodworms we feed our aquarium fish eat algae and decomposing organic material in the freshwater environments where they live.

However, the hefty marine bloodworms that are so popular as fish bait are true predators. Those creepy critters use unique copper fangs and a venomous bite to catch and kill smaller creatures like worms and crustaceans.

What are bloodworms good for?

Bloodworms provide a tasty supplement to regular dried fish food. They are great for conditioning fish before breeding and for feeding picky fish that refuse flakes and pellets.

Is it OK to touch bloodworms?

Most people suffer no serious reactions after handling bloodworms, but some are allergic to these tiny creatures.

The cause of bloodworm allergies aren’t very obvious but they seem to get worse over long periods of time. Even if you don’t show any symptoms at first, the safest route is to use caution and wear gloves or wash your hands thoroughly after handling them.

Do bloodworms live in humans?

Bloodworms live in freshwater and they can’t survive inside our bodies. These wiggly worms are not parasites but they do have a kind of creepy name! Bloodworms eat detritus, rotten plant material and algae down at the bottom of lakes and other freshwater bodies.

Final Thoughts

Live, freeze dried or frozen bloodworms are an excellent fish food if you limit your fish to helping every once in a while. These worms are packed with iron and protein and fish go crazy for them. Feeding bloodworms is easy too, just make sure you keep them fresh and avoid touching them with your bare skin just in case.

Do you feed your fish bloodworms? Let us know if you prefer frozen, freeze-dried or live bloodworms in the comments below!


  1. Two contradictory statements in this article. First, it says “freeze-dried bloodworms have more nutritional value,” in comparison to frozen.
    Then later it says “Freeze-dried bloodworms are the most convenient but the least nutritious form of prepared bloodworms.”


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