Bloodworms For Fish: Feeding Guide (2024)

Featured Image -PT-0134 - blood worms for fish
Featured Image -PT-0134 – blood worms for fish
Dr. Mollie Newton
Published by Dr. Mollie Newton PHD| Senior Editor
Last updated: June 8, 2024
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Although they may look somewhat creepy, both fresh and preserved bloodworms are excellent sources of protein and a favored food for fish. These worms provide a convenient feeding option for fish, invertebrates, and other aquarium inhabitants, thereby playing a crucial role in various dietary plans.

Are bloodworms right for the aquarium fish you have in your tank? Read on to find out!

Article Summary

  • Bloodworms, available in two species – midge fly larvae and Glycera family worms, serve as a high-protein, favored food for aquarium fish and invertebrates, with midge fly larvae being red and suitable for low-oxygen environments, while Glycera family worms are pink to cream in color, larger, and found in marine waters.
  • Bloodworms should be considered a supplement, not a staple diet, as they lack some essential amino acids.
  • You can purchase bloodworms from local pet stores or online, but be cautious about their quality and condition upon arrival.

What Are Bloodworms for Fish?

While it may sound like it describes one particular species, the term bloodworm actually refers to several. The two species labeled as “bloodworms” commercially are the Glycera family and the larvae of the Chironomidae, or adult midge flies.

Midge Fly Larvae

Bloodworms in Plastic Container
Bloodworms in Plastic Container

The larvae of the non biting midge fly or blind mosquito larvae is noticeable for its bright red coloration and smaller size. The color is the result of the high iron content of their blood, and allows them to survive in lower oxygen, more polluted water and environments.

The larvae of midge flies stay small, and will not grow larger than an inch or so. As such, they make great food for fish of all sizes.

Glycera Worms

Glycera (Bloodworms)

These are a variety of bristle worms that survive underwater and are typically found on the bottom of marine waters. These tend to be more of a pink to cream color, and can grow upwards of 14 inches. These bristle worms also have a poisonous bite which they used to capture prey in their natural environment.


Bloodworms are essentially the bottom of the aquatic food chain, and many saltwater fish will be natural predators for them. Marine fish such as the blue mandarin and crustaceans like shrimp can often be found preying upon them in the wild, where they yield a plentiful source of good protein.

What Do Bloodworms Look Like?

Depending on the variety that you’ve purchased, there may be some differences in the appearance of your bloodworms. Those of the Glycera family will be longer and more creamy in coloration, while the larval midge fly bloodworm will be much shorter and bright red in color.


A bloodworm of the Glycera family will not change into any other form, while a bloodworm that is a larval midge fly will eventually metamorphose into a flying form. That being said, those once in the water they will be unable to change!

The main thing to note with regard to which variety you feed your salt or freshwater fish is the size. Smaller fish will need the variety that best fits in their mouths, as they may be unable to eat and properly digest a bloodworm if it is too big for them.

What Fish Are Bloodworms Good For?

Blue and Orange Betta
Blue and Orange Betta

While live bloodworms can make a great option for any meat eating fish and even for carnivorous snails, there are some species in particular which benefit from this protein-rich fish food.

Betta Fish

These tropical fish are carnivorous, meaning they need lots of protein in their regular diet. In addition to brine shrimp, feed frozen bloodworms to these fish to ensure that they get a balanced diet full of the nutrients they need to grow.

Other fish such as Kuli loaches, African cichlids, mollies, and discus fish will be sure to love having bloodworms as a tasty treat in the tank.

Should Fish Eat Bloodworms?

Absolutely! As long as a fish can eat meat, if you feed bloodworms to them they should be happy swimmers. Feeding blood worms for fish can be a great way to introduce a rich source of protein to your fish tank. A varied diet is the best way to ensure that your fish live a long, happy life.

As a special note, aquarium fish that are strict herbivores, meaning that they do not eat meat, should not be fed bloodworms. These fish will not eat them!

However, bloodworms for fish should be considered more of a supplement, rather than the staple diet of your tank inhabitants. The reason being that your fish’s diet needs to be complete with other essential amino acids than what may be found in bloodworms alone.

Feeding your fish bloodworms in addition to the primary foods that you feed your fish such as flakes or pellets can be a great option.

Where Can You Buy Bloodworms?

There are several different places you can purchase a bloodworm supply.

Your local pet store is sure to have all of the listed options, and they may be able to make specific recommendations with regards to the needs and requirements of the fish that you have in your tank.


You can also purchase bloodworms online, but should be careful when doing so. Be sure to buy only those that are food-grade and actually meant for fish to eat, as some may contain particles on shipping material or other inedible pieces otherwise. And make sure to soak your worms before feeding them if you purchase one with high levels of crude protein.

Additionally, be aware that shipping frozen options comes with its own hazards. Shipping any frozen goods comes with the risk that it may melt during shipping and spoil, and ordering bloodworms live does not always mean that they will arrive in the same state.


When looking at “grade,” always go for the grade A over grade B options. This will ensure that you get the highest quality food possible.

Types of Bloodworms

Bloodworms in White Background
Bloodworms in White Background

There are several different options when it comes to how your fish can enjoy bloodworms. Most pet stores should carry all of these bloodworm products, from live worms all the way to bloodworm eggs if you want to raise your own.

Live Bloodworms

Live bloodworms make for a great option for fish that like to hunt their prey such as bettas and axolotls. Live foods allow your fish to activate its latent hunting instincts, which many fish prefer compared to having to eat pellets.


The downside to live bloodworms is that they require more care than other options. Live food in general needs to either be kept carefully if you’re looking to store long term, or be used right away.

When you feed your fish live bloodworms, remove them from the water they’re stored in and rinse them well since they do have a higher risk of carrying infection and disease.

Frozen Bloodworms

Frozen bloodworms most typically come in a single frozen block or several thin sheets of worms that will need to be defrosted prior to being placed in the tank. Frozen worms have the advantage of longer term storage than live, as a frozen bloodworm can last for several months when left in the freezer.


There are a few different methods when it comes to defrosting. You can either place the blocks directly in your fish tank to thaw and feed your fish as they do so, or you can thaw them prior to adding them by placing them in a small container with some of the tank water. Either way works just fine when it comes to providing a tasty treat for that fish love.

Freeze Dried Bloodworms

Similar to frozen, freeze dried bloodworms have the added advantage of longer shelf life. Frozen or freeze dried bloodworms lose some of the nutritional content through the process, but they still make for a great option for most fish.

Freeze dried bloodworms will float on the top of the tank, so when feeding bottom feeders soak them for around ten minutes prior to adding to the tank so that they will sink.


When it comes to the freeze dried variety, you may notice two different grades available. Grade A freeze dried bloodworms should be the ones you look for, as this freeze dried food will have the least amount of non-bloodworm particles. Grade B, on the other hand, will contain more non-bloodworm particles, which can potentially be hazardous to your fish.

How Many Bloodworms Should I Feed My Fish?

Person Holding Bloodworms
Person Holding Bloodworms

This can vary widely between different species of fish, along with the variety of food that you’re using. Freeze dried varieties will contain less nutrition than live foods, so you may need to feed more than you would otherwise.


As a good general rule of thumb when feeding fish bloodworms, if there is still uneaten food within 30 minutes of feeding, remove it so that it doesn’t begin to rot. This will help prevent ammonia levels rising to dangerous levels and potentially causing toxic shock in your tank.

Can Fish Eat Bloodworms Everyday?

Fish can absolutely eat bloodworms every day, but this should be in addition to other sources of food such as pellets or flakes.

The reason for this is that bloodworms alone do not contain all of the essential nutrients that your fish will need, especially if they’re an omnivore such as goldfish who need more of a variation of plants and proteins in their diet.

Are Dried Bloodworms Good For Fish?

Dried bloodworms make for great fish food! While they may not carry the full protein load or trigger the natural hunting instinct like live worms would, they make for a great choice for keeping your own bloodworms.

The nice thing about a dried bloodworm option is that they last much longer than their live counterparts, and take no input prior to feeding time.

Can I Leave Bloodworms in the Tank?

After feeding, any leftover bloodworms in the tank should be removed. The problem is that they will soon begin to degrade upon being left in the tank.

As they continue to break down, they can raise the ammonia levels and wreck the water quality of your fish, leading to health problems such as ammonia poisoning and toxic shock if left untreated. Excess bioload caused by leftovers can also lead to detritus worm infestation.


A good way to ensure that your water quality is at the proper level and maintain a healthy aquatic ecosystem for your fish is with consistent testing. Aquarium test kits are readily available at most stores and can provide a wealth of valuable information such as pH, oxygen concentration, and ammonia levels.

What Can I Do With Leftover Bloodworms?

A good option if you’re an outdoors person is to use them for fishing! Preserving them in a little bit of salt can help keep live bloodworms from spoiling if they’re not at a good place to feed fish in your tank, and they make great bait for a variety of sport fish species such as perch and striped bass.

Here’s an informative video on how to preserve bloodworms…

How to Preserve Bloodworms

Do Bloodworms Bite?

Bloodworms of the Glycera family will indeed bite if given the chance. They have a mild poison that has been equated to a bee sting in potency, which as many people can tell you can be quite painful. That being said, they will not actively seek to bite you or other fish but may nip at you when handled.

Bloodworm Bite Effect on Human

In a recent study, it was found that the toxin genes expressed by bloodworms are actually quite similar to those produced by bees and wasps! Additionally, it’s being considered for use in human pain killers in future studies.

Similar to the allergic reaction caused by a bee sting, a bloodworm bite can cause serious irritation or severe allergic reactions in certain people.

As a result, people with allergies should wear gloves thick enough to prevent a bite.

That being said, most people would not consider bloodworms dangerous in general, just be aware and use caution if you think you may have bloodworm allergies.


Throughout today’s article we’ve looked at bloodworms for fish in providing a balanced diet.

When feeding your fish bloodworms there are a variety of options, from freeze dried blood worms to those that come in frozen blocks so there is sure to be a method that best suits the needs of the fish in your tank.

Feel Free To Share!

As always thank you for reading this post on bloodworms, I hope that it has answered all of your questions.

Feel free to share this information with any other fish fanatics you may know, I wish you the best of luck on your continued aquarium adventures!

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