Do Cardinal Tetras Eat Bloodworms? A Guide To Their Diet

Cardinal tetras are one of the most popular freshwater fish in the aquarium hobby. These fish can live happily even with minimum tank facilities. Besides this, the food requirement of these fish is also not very high. Cardinal tetras are omnivorous fish and can eat both plants as well as meats in nature. But can Cardinal tetras eat bloodworms?

Yes, Cardinal tetras can eat bloodworms. Cardinal tetras are not picky eaters and can eat all kinds of worms available in the market. Among these, bloodworms rank high on their preference list because they contain more proteins as compared to other types of worms.

If you are still unsure whether or not to feed your Cardinal tetras with bloodworms, read further to clear your doubts.

Do Cardinal Tetras Eat Bloodworms?

Cardinal tetras do eat bloodworms. Since they’re omnivores, Cardinal tetras eat most aquarium foods. They usually feed on small insects and worms like bloodworms in the wild and plant matter such as algae or aquatic plants.

Bloodworms are generally too big for cardinals to swallow whole and will need either hiding within other foods or cut in half before feeding them. However, Cardinal tetras will eat bloodworms out in the open and may even pick at them when they sink to the bottom of an aquarium.

Since bloodworms are a great source of protein, Cardinal tetras will benefit from them in their diet. However, Cardinal Tetra fish are easy keepers and can eat a wide variety of foods, including flake food or pellets and frozen brine shrimp, daphnia, Beefheart, live black worms.

What Are The Benefits Of Bloodworms In Cardinal Tetras Diet?

Cardinal Tetras are omnivorous. Thus, they need an equal amount of veggies and protein sources in their diet. So, bloodworms can be a great food to feed Cardinal tetras.

Some of the advantages of including bloodworms in the diet of Cardinal tetras are:

Bloodworms Improve The Health Of Cardinal Tetras

Cardinal tetras are an active species of fish. Thus they need high protein food in their diet. Bloodworms make Cardinal Tetras energetic and healthy.

Bloodworms Are Nutritious

Cardinal Tetras are predatory species of fish. Thus, they need high protein food to remain active and strong. Bloodworms provide Cardinal tetras with proteins, fatty acids, Vitamin B12, calcium, etc., which is highly beneficial for the health of Cardinal Tetra fishes.

Cardinal Tetras Prefer Bloodworm Over Other Food

Cardinal Tetras are omnivorous. Thus, they need different kinds of food in their diet. However, Cardinal Tetras have a natural liking for bloodworms, making it easier to feed Cardinal tetra fishes with Bloodworm.

Bloodworms Are Rich In Protein-Content

Cardinal tetra fishes are omnivorous species of fish that require high protein content in their food. Bloodworms provide Cardinal Tetras with a good amount of proteins, which is beneficial for muscle and blood development and strengthens Cardinal Tetras bone tissues.

Bloodworms Boost Up The Immunity Of Cardinal Tetras

Cardinal tetra fishes are active species of fish, which makes them highly susceptible to diseases. These fish have a natural liking for bloodworms that helps them to build up their immunity against various health issues.

What Are The Disadvantages Of Bloodworms In Cardinal Tetras Diet?

Undoubtedly, there are many advantages of including bloodworms in the Cardinal tetras diet. Yet, too much of everything is terrible. Therefore, Therefore, Cardinal tetras’ diet should not favor too many bloodworms. Moreover, some disadvantages pf bloodworms are:

If Cardinal Tetras eat too many of them, they start to starve from the lack of nutrients. Most bloodworms consist of 70% water. Thus, Cardinal tetras will need more food with high nutritional value, such as flakes or pellets, to get enough nutrients on their bloodworm diet.

Another disadvantage of the Cardinal tetras diet with bloodworms is the lack of calcium and vitamins for proper development, especially after the spawning period. Cardinal Tetra males tend to eat their offspring if there are not enough nutrients in the Cardinal Tetras diet. Therefore, it can be a significant problem during the breeding stage when high amounts of calcium and proteins are not present in the Cardinal Tetras diet.

Besides this, bloodworms are rich in protein and fat that are difficult to digest. Cardinal tetras with insufficient fiber in their diet can suffer from constipation or diarrhea, often difficult to cure.

How Much Bloodworms Should I Give Cardinal Tetras?

Cardinal tetras will eat bloodworms frequently, but it is important to provide just the right amount. The maximum number of bloodworms that you can feed Cardinal tetras is three worms at once. If you give them more than this many in one feeding, they do likely not finish all of them and may leave some uneaten.

Just because cardinal tetra fish loves eating bloodworms doesn’t mean you should feed them with an excessive number of worms. Once you feed three worms at once, try to ensure that your fish ate all of them. Thus, it will eliminate the chances of overfeeding and tank pollution.

How Often Should I Feed Cardinal Tetras With Bloodworms?

Cardinal Tetras eat bloodworms as a treat. They should be fed with them once or twice per week, but it depends on how much you provide your Cardinal tetra and what other foods they are getting.

If you have an overfed Cardinal tetra that feeds too many treats, they may become obese. Cardinal tetras are naturally slender fish, so too much food can cause them to look bloated and unhealthy.

Some Cardinal tetras owners prefer to use bloodworms as their primary food source, but it is also important to feed them other types of foods. Cardinal tetras need various meaty and plant-based foods such as brine shrimp, daphnia, grindal worms (tubifex), blackworms (bloodworms), and more.

What If My Cardinal Tetras Won’t Eat Bloodworms?

Sometimes Cardinal tetras may not like bloodworms, especially if you just got them. For example, when Cardinal tetras are new to the tank, they may feel stressed. So, they stop eating for a few days or sometimes even weeks until they relax in their new environment.

Cardinal Tetra fish will usually eat bloodworms if they are hungry, but you can always try to feed other foods as well. Some examples of foods that your fish may eat are live or frozen brine shrimp and daphnia, micro worms, tubifex cubes, chopped earthworms, etc.

Some Cardinal tetras do not prefer bloodworms, and it’s ok. Just make sure that your fish is not starving. Then, you can feed them various options other than the bloodworms, and they will be fine.

If Cardinal tetras still don’t eat, you can consider feeding them commercially prepared foods for tropical fish or getting high-quality flake food with the nutrients they need to survive. However, when this case persists for more than a few days, it is best to seek help from professionals.

Some FAQs

What Do Cardinal Tetras Eat?

Cardinal tetras eat a wide variety of foods, including blackworms, crickets, bloodworms, and more. Since they are omnivorous, they also eat plants and vegetables like spinach, kale, and zucchini.

How Long Will Cardinal Tetras Live?

Cardinal tetras can live up to five years in captivity. In the wild, they can live up to eight years.

What Do Cardinal Tetras Look?

Cardinal tetras have a bright red coloring that makes them highly recognizable. Still, some cardinal tetra varieties also have blue and yellow colors mixed in with their vibrant red coloration. They look similar to neon tetras, but they are slightly larger and have more red coloring.

How Big Can Cardinal Tetras Get?

Cardinal tetras are small fish that typically grow around two inches long. However, most aquarists consider Cardinal tetras juveniles when they’re around an inch long.

Can I Feed Pregnant Cardinal Tetras Bloodworms?

No, Cardinal tetras should not eat bloodworms when they’re pregnant since Cardinal tetra fry is tiny and has an underdeveloped yolk sac. It’s important to feed them baby brine shrimp instead of bloodworms.


In conclusion, Cardinal tetras do not have a particular preference for eating bloodworms. They can eat both small and large-sized bloodworms without any problems. However, because the size of these worms is considerably smaller than that of their mouths, Cardinal Tetra owners need to be extra vigilant when feeding them with bloodworms as they might end up choking on them. It is not only dangerous but also quite sad for Cardinal Tetras.

If you are planning to feed your Cardinal tetra with these kinds of worms, then ensure that the size of the worm does not exceed more than one-third of the Cardinal Tetra’s mouth.

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