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can you give hermit crabs tuna?

Can Hermit Crabs Eat Tuna Fish?

The foods that hermit crabs uncover at the beach are completely different from what you might find in the kitchen. That may make you wonder if hermit crabs are allowed to eat tuna fish. Tuna is seafood, but hermit crabs would rarely encounter this food source when living in the wild.

Hermit crabs can eat tuna fish. Their resilient digestive systems are perfectly tailored to handle the proteins and enzymes. In fact, tuna is one of the most nutritious types of fish you can feed them. The vitamins, minerals, and protein will give your hermit crabs a strong immune system, a sturdy exoskeleton, and plenty of energy.

However, there are risks involved with canned tuna fish. It’s usually high in salt, oil, or sauce. This can give your hermit crabs an overdose of fat and sodium, which is harmful long-term. Likewise, tuna may contain high amounts of mercury. To avoid these problems, only feed your hermit crabs organic tuna in springwater.

Can You Give Hermit Crabs Tuna?

Tuna is a great food to offer your hermit crabs. As a good source of protein, hermit crabs will use it to fuel their growth and energy levels. Whether you open up a can or set a tiny piece of tuna steak in the tank, your hermies will enjoy it.

Tuna is also readily available at grocery stores, corner markets, and online. That makes it a convenient, accessible, and affordable way to feed your hermit crab.

Do Hermit Crabs Like Tuna?

Hermit crabs are not picky eaters. They will munch on any food they’re provided, so long as it provides an aroma and is easy to pick apart.

With that said, because tuna is a type of seafood, hermit crabs may be more receptive to it than other meals. It will smell and taste like the meat they’re used to in the wild, enticing them to keep feasting.

is tuna good for hermit crabs?

Is Tuna Safe For Hermit Crabs?

Tuna, by itself, is safe for your hermit crab to eat. However, there are risks that come with eating tuna, both canned and fresh. For fresh tuna, the biggest factor to keep in mind is the presence of mercury. For canned tuna, salt comes into play alongside mercury as a danger.

This doesn’t mean that you should completely cut out tuna from your hermit crab’s diet. You just need to monitor the kind of tuna you feed them and where you buy it. It’s easy to mitigate these risks. Tuna fish has a lot of health benefits for your hermit. With a bit of care and attention, the advantages can easily outweigh the risks.

Is Tuna Good For Hermit Crabs?

With the large amount of nutrients found in tuna, it is sometimes touted as a superfood. That’s true for hermit crabs and people alike.

Indeed, tuna contains a lot of vitamins and minerals, as well as other compounds that are good for your hermie’s health. Here are some reasons this fish should be added to mealtimes in your tank.

Great Source Of Protein

As omnivores, it’s good to provide your hermit crabs with a healthy source of animal protein. This helps mimic their natural diet in the wild and fuels their bodies with energy and muscle-building nutrients.

Tuna fits the bill perfectly. Besides being cheap and easy to buy, just one can of tuna contains 42 grams of protein. That’s paired with a wide variety of amino acids.

Healthy Exoskeleton

Aside from being protein-dense, tuna fish also contains a lot of vitamins and minerals.  One of the most notable is vitamin D. In fact, tuna is so rich in vitamin D that just 3 ounces fulfill 50% of the recommended daily intake for humans. You can imagine what a tiny bite will do for a hermit crab a fraction of our size.

Vitamin D has many different roles in the body, such as strengthening the immune system and ensuring healthy growth. Most importantly, vitamin D will keep your hermit crabs’ exoskeletons thick and resilient.

When paired with the vitamin B6 and selenium found in tuna, your hermit crabs will have more productive molts. Their new skins will grow in better prepared to shield them against falls, scuffles, and daily life.

The benefits don’t stop there. Tuna fish contains several other trace nutrients that will safeguard your hermits from harm. The main ones include:

  • Calcium
  • Phosphorus
  • Potassium
  • Iron
  • Zinc

Healthy Immune System

While vitamin D strengthens the immune system, nothing does this job better than vitamin C. Tuna has this nutrient in abundance, which pairs well with manganese, zinc, and selenium. This will boost your hermit crab’s ability to resist infection, sickness, and parasites.

If you’ve just purchased a new batch of hermits from the pet store, this is a great food to offer. They can weather the stress of relocation and better handle their quarantine period, with a quick picker-upper in the form of tuna.

On top of that, tuna also contains different antioxidants that can help your hermit crab remain happy and healthy. If they’ve just weathered the transition period or overcame a sickness, this can help them feel more energized than before.

Can Hermit Crabs Eat Canned Tuna?

Canned tuna is an inexpensive and convenient way to give protein to your hermit crabs. It can last for years in your pantry, and it takes up very little space.

Of course, there are health risks associated with canned tuna. It’s known to contain high amounts of salt, and in some cases, even mercury. If it’s canned with oil or sauces, these ingredients may be harmful to people with allergies or weight issues, but also hermit crabs. After all, the crustaceans need to feed on ingredients found in their natural habitats. It also takes a far smaller dose of salt or oil to become sick.

Hermit crabs should not be given tuna in a can. You can get around this rule, though, by picking the right brands. Many owners regularly add canned tuna to their pets’ diet without harm, so just pick carefully.

Here are types of canned tuna you can buy on the market. Which are healthy for your hermit crab?

Tuna In Oil

Of all the types available on the market, this is the canned tuna you should avoid. Low-cost brands are packed with extra oil and salt. This adds flavor but also skyrockets the sodium, calories, and fat content of the fish.

Salt and oil are important for hermit crabs, but it’s easy to provide too much with canned tuna. Instead, the two ingredients should come from healthier food sources, preferably in small amounts.

Tuna in Springwater

Tuna in springwater is a much healthier alternative to tuna in oil. While it still contains salt, the amount is significantly less. Most importantly, tuna in springwater contains fewer calories and fat.

If you have to choose between brands, opt for those with little to no added ingredients. This will be the most natural for your hermit crabs. In the wild, they would only feast on tuna that’s washed ashore by itself; they wouldn’t season or marinate it.

Organic Tuna

Aside from ingredients added to provide flavoring, some tuna is canned with preservatives. You can find a shortlist of these on the side of most containers. While they are not immediately harmful to your pets, hermit crabs may still have adverse reactions.

If you feed tuna with preservatives regularly, your hermits may have a shorter lifespan. That makes organic tuna the best option, as it will be the freshest, most natural kind.

Health Risks of Tuna For Hermit Crabs

Buying the right kind of tuna for your hermits won’t just involve picking an organic label. You need to watch out for mercury and salt. Even in the freshest brands, this may be a problem. Luckily, there are ways to prepare your canned tuna so that it’s safe for hermit crabs.


Mercury is a chemical that is used in many items, including thermometers and automotive light systems. However, it is also known for its toxicity. It is harmless outside of the body. Once it is absorbed, however, it becomes a neurotoxin, harming the brain and nervous system.

Because of industrial activity, mercury can leach into the water and become absorbed by ocean life. The highest levels of mercury are found in large fish species. This is because larger fish eat smaller fish, which, in turn, eat even smaller fish. As the food chain goes up, more mercury can be found in a single fish.

Other than tuna, fish species you should keep an eye on are swordfish and wild sturgeon. The presence of mercury in tuna has been widely studied. According to the Journal of Environmental Toxicology and Chemistry, people who regularly ate tuna had higher mercury levels compared to those who didn’t. Most notably, people in the study were not aware of mercury levels in the fish they ate.

Crabs as a whole may also contain mercury. However, your average hermit crab will have tiny amounts, if any. Terrestrial kinds stay out of the hot zones, and they’re not large enough to build up a lethal amount in their system. Nonetheless, you can disrupt that balance if you offer your hermits tuna that’s dense with mercury.

can hermit crabs eat canned tuna?

How To Avoid Mercury For Hermit Crabs?

There are steps you can take if you’re afraid of mercury content.

  • Opt for smaller tuna species, like skipjack.
  • Avoid larger tuna, like bluefin.
  • According to Environmental Research, light tuna has a lower level of mercury.
  • You can remove other fish in your hermit crabs’ diet to really avoid mercury.

This is especially important if the other species are large fish or contain high amounts of mercury. Aside from lowering the risk factor, this is also an excellent way to add variety to your hermit crab’s diet.

If you’d rather be safe than sorry, consider swapping tuna out with other types of fish. Smaller species, like salmon, trout, and anchovies, are great for hermit crabs.


Hermit crabs need saltwater to thrive and survive. However, they can easily get too much in their diet and become ill. Tuna is a risky food because of this, as it’s packed with high levels of sodium. This helps to preserve the fish and adds flavoring, but offering a normal salt-packed can of tuna to your hermit crab could prove lethal.

How To Avoid Salt For Hermit Crabs?

To avoid this problem, always choose canned tuna brands that do not have added salt. Tuna packed in water is the best option. You can also peek at the ingredients list to be sure, as organic brands even break this rule.  

How Much Tuna Should You Give Your Hermit Crab?

Hermit crabs need a high amount of protein but still in moderation. Animal and plant proteins should consist of1/4th your hermit crabs’ meals. This should be dominated by animal proteins, with some veggies, fruits, and berries.

You should offer protein to your hermit crab at least once a day. This can be tuna fish exclusively, or you can swap it out with other meats throughout the week. Hermit crabs get bored of food over time, so variety will help.