Betta fish are among the most popular captive fish in the world as they look so beautiful. Many fish owners like to keep marine hermit crabs in an aquarium, as they eat algae and reduce the need to clean a tank often. Alas, the species shouldn’t live together.
Bettas are freshwater fish, while hermit crabs are native to the ocean. Creating a shared living environment where fish and hermit crabs will feel comfortable and flourish is difficult.
Hermit crabs and betta fish also have disparate dietary needs. Betta fish don’t sustain themselves purely on flakes; they’re carnivorous and need protein to survive; hermit crabs rely more on calcium-rich foods.
Perhaps more importantly, betta fish are aggressive and territorial, which has earned them the name “Siamese fighting fish.” Hermit crabs are typically docile but will retaliate if attacked.
If you wish to keep betta fish, don’t rely on hermit crabs to keep their tank clean. If you want live fish to keep your marine hermit crabs company, find a more docile, saltwater fish.
Bettas and hermit crabs are just too different to co-exist safely.
What Are Betta Fish?
Betta fish (Betta splendens) are native to Thailand but also found in Australia, Latin America, the Caribbean, and Singapore. This unofficial name stems from the betta’s territorial nature.
Many fish owners like Bettas due to their striking appearance. These fish live up to three years (if they don’t kill each other in captivity), grow up to three inches in length, and prefer a carnivorous diet to traditional fish flakes.
Anybody looking to care for betta fish should only combine females, as males of this species are the most prone to aggression. Even then, think carefully before pairing Betta fish with another aquatic animal, including hermit crabs.
Can You Put Hermit Crabs with Betta Fish?
A terrestrial hermit crab can’t live with any fish. Land-based hermit crabs can’t breathe underwater and will drown within an hour of being placed in a deep aquarium with no escape route.
Marine hermit crabs are the opposite; they need to live in water, as they can’t breathe on dry land for a prolonged period. Aquatic hermit crabs also eat naturally occurring algae in a fish tank, so some fish owners use them as an organic clean-up crew.
If you plan to pair marine hermit crabs with betta fish, you must first understand the needs of each animal. Here are the optimum tank conditions for Betta fish and marine hermit crabs:
| Betta Fish | Hermit Crabs | |
| Water Temperature | 75 – 86 OF | 72 – 78OF |
| Water pH | Around 7.0 | 8.0 – 8.4 |
| Water Hardness | 5 – 20 DH | 8 – 16 DH |
Except for Clibanarius Fonticola, it’s rarely kept in captivity, it doesn’t have a nickname, hermit crabs are saltwater animals, and bettas are freshwater fish.
This means that the water pH between these two animals is incompatible. Betta fish can cope with a slightly higher acidity than the freshwaters they’re used to but are unlikely to flourish.
Keeping water at a temperature safe for hermit crabs is also at the lower end of what a betta will need to remain comfortable. Perhaps most importantly, they have wildly different temperaments.
Do Hermit Crabs Eat Betta Fish?
Hermit crabs won’t actively hunt and attack fish to eat.
In truth, hermit crabs in a fish tank just want to be left alone. They may eat a dead betta that sinks to the tank’s floor but will practically never attack and kill such a tankmate without provocation.
Will Betta Fish Attack Hermit Crabs?
While hermit crabs don’t hunt and kill betta fish, their docility should not be mistaken for wholesale subservience. If a betta fish attacks, the hermit crab will defend itself. The large cheliped of a hermit crab can easily kill a small betta.
This is a concern, as betta fish are likely to attack hermit crabs sooner or later. They earned the nickname “fighting fish” for a reason. If a betta considers a hermit crab in its way, it’ll attack.
This lack of fear is admirable, but it’ll cost a betta fish its life when paired with hermit crabs. They defend themselves from perceived threats and predators and will emerge victorious from most conflicts.
Can Hermit Crabs Eat Betta Fish Food?
Hermit crabs are opportunistic scavengers, so they’ll eat anything unmoving they can find. As discussed, many people keep hermit crabs in a fish tank to eat algae. Hermit crabs will also happily eat fish flakes that sink to the bottom of a tank.
Betta fish can be fed flakes, though it’s best to offer a brand of flakes or granules especially designed for bettas. These will be rich in protein, which is essential for the carnivorous betta. Bettas also like to eat live or frozen shrimp or bloodworms.
Hermit crabs are omnivorous, so they can also eat these foods. Hermit crabs rarely hunt live prey; their primary need is calcium. While hermit crabs also need protein, sustaining themselves on a betta-specific diet is unlikely to meet their nutritional needs.
Betta flakes also contain ethoxyquin. While the International Journal of Food Sciences lauds the antioxidant properties of this preservative, it’s harmful to hermit crabs if regularly ingested over a prolonged period.
We also need to consider how a betta will react if it spots a hermit crab eating its food. We have discussed many times how territorial these fish are. Conflict will follow if a fish attacks a hermit crab for ‘stealing’ its meal.
Alternative Tankmates for Betta Fish
Betta fish can’t live in groups, as they’ll fight. Males are the likeliest to come into conflict, but even female betta fish will likely come to blows eventually. The territorial nature of these fish will win out.
Rather than hermit crabs, consider keeping nerite snails in a betta fish tank. Like hermit crabs, these snails will eat algae and keep a tank clean. However, unlike hermit crabs, they will mostly be ignored by bettas. Conflict will not arise, and both animals will be safe.
Nerite snails can live in freshwater tanks alongside betta fish and will not hatch their eggs in such surroundings. They are readily available from pet stores specializing in fish, rarely costing more than $3 each, and you can keep several in a betta tank.
Think carefully if you are determined to keep other fish with your bettas. Avoid any fish with bright, colorful scales, as these will aggravate the bettas. Stick with freshwater fish that dwell at the bottom or middle of a tank, as bettas will stick to the top.
Alternatives to Betta Fish to Keep with Hermit Crabs
Hermit crabs don’t need to live with fish, but they can do so with species other than the betta.
If you want to pair fish with hermit crabs, choose saltwater fish with a similarly gentle temperament, unlikely to cause conflicts. Some ideal fish to pair with hermit crabs include:
- Clownfish
- Damselfish
- Gobiidae (aka Gobies)
- Pajama Cardinalfish
- Royal Gramma
- Wrasses
Many of these fish live alongside hermit crabs in the ocean and will be unconcerned by their presence in a tank. It could be argued that hermit crabs make better tankmates than fellow fish, as they’re less likely to come into conflict over food, territory, or resources.
Betta fish and hermit crabs are from two different worlds and would never interact in the wild. To this end, this is nothing to gain by forcing them to share an aquarium. While some types of fish can happily share a tank with hermit crabs, bettas aren’t among them.
