Hermit crabs are thought of as land creatures. In reality, just 1 in 7 hermit crab genera is terrestrial. Many species of hermit crabs live in the ocean. Naturally, marine hermit crabs must also live underwater if kept as pets.
Hermit crabs and fish live side by side in the sea, and can do so in a tank. You just need to ensure that the fish and crustaceans are compatible. That means sharing preferences of water quality, temperature, and quality. Clownfish, damselfish, gobies, cardinalfish, and wrasses are good tankmates for hermit crabs. Avoid putting goldfish, betta fish, or cichlids with hermit crabs.
Pairing hermit crabs with fish can be rewarding. Both species will enjoy the company, and hermit crabs can look stunning in an aquarium. Just ensure you understand the needs of the crustacean. Hermit crabs, whether terrestrial or marine in nature, are delicate animals.
Can Hermit Crabs Live in a Fish Tank?
A fish tank, or aquarium, is considered the perfect home for hermit crabs. An aquarium of at least 10 gallons in size will meet the following criteria:
- Solid walls to retain heat and humidity
- Enough space for exploration and digging in the substrate
- Protection from external fumes
- A solid roof to prevent escapes
- Comparatively easy spot and deep cleaning
This means that, in theory, hermit crabs can live alongside fish. However, not all hermit crabs can breathe unwater. To house fish and crustaceans together, you must adopt marine hermit crabs.
Marine Hermit Crabs vs. Terrestrial Hermit Crabs
As per the Annual Review of Ecology and Systematics, over 800 species of hermit crab exist. This means they come in all shapes and sizes. The Ecuadorian hermit crab is less than half an inch in size. The coconut crab, though, can grow to over 3 feet.
What matters most is determining whether a hermit crab lives underwater or above ground. Marine hermit crabs, as the name suggests, live in the ocean. These crustaceans cannot breathe long on land. Terrestrial hermit crabs are the opposite. They cannot breathe underwater indefinitely.
Most of the guides on this site pertain to terrestrial hermit crabs. These are the crustaceans purchased from a seafront gift store. Shop owners will collect terrestrial hermit crabs from the beach. These are then provided with aesthetically pleasing shells and sold to tourists.
There are 7 recognized families of hermit crab, and 6 of these live underwater. See the table below for a summary:
|Coenobitidae (Terrestrial)||Ecuadorian, Australian, Blueberry, Coconut, Strawberry, and Caribbean hermit crabs|
|Diogenidae (Marine)||Scarlet Reef, Eye Spot, Furry, Blue Leg, Whitebanded, Zebra, and Anemone hermit crabs|
|Paguridae (Marine)||Arcadian, Black-Eyed, Whiteknee, Polka Dot, New Zealand, and Blueband hermit crabs|
|Parapaguridae (Marine)||Oncopagurus, paragiopagurus, and strobopagurus. Live in deep waters and largely unavailable as pets|
|Parapylochelidae (Marine)||Believed extinct, new species have been discovered. As per Neues Jahrbuch für Geologie und Paläontologie, this includes the mesoparapylocheles michaeljacksoni. This name was chosen as a tribute to the deceased pop star.|
|Pylochelidae (Marine)||AKA symmetrical hermit crabs. This family is endangered and largely unavailable as pets|
|Pylojacquesidae (Marine)||Pylojacquesia colemani and lemaitreopsis holmi – both rare, newly discovered, and unavailable as pets|
Terrestrial hermit crabs of the coenobitidae family cannot live with fish. They will drown in under an hour. These hermit crabs have gills but have evolved to live on land. Their lungs breathe oxygen and soak in water periodically to retain water.
Any species of marine hermit crab can, theoretically, live with fish. As always, though, caveats apply. The unique needs of both animals must be taken under advisement. You must ensure that inter-species living conditions are compatible.
Can Hermit Crabs and Fish Live Together?
Hermit crabs enjoy companionship from their own species. In the wild, hermit crabs live in colonies. Avoid leaving one hermit crab alone in a fish tank. It will quickly grow stressed and overwhelmed.
If you adopt marine hermit crabs, these crustaceans can live with fish. Hermit crabs can be territorial, but they are social by nature. Most crabs will welcome the company. The best hermit crab breeds to pair with fish include:
- Blue Leg
- Dwarf Red Tip or Yellow Tip
- Polka Dot
- Electric Blue or Electric Orange
Seek advice before placing any hermit crab in a fish tank, though. Terrestrial hermit crabs cannot be left underwater. Marine hermit crabs will be purchased from an aquatic pet specialist, not a seafront gift store.
In addition, consider the water needs of fish and crustaceans. Not all exotic fish can survive in saltwater or freshwater. In addition, hermit crabs need water temperatures between 72-78 degrees Fahrenheit to flourish. Some fish require warmer or cooler climes.
Will Hermit Crabs Attack Fish?
Hermit crabs are omnivorous, opportunistic scavengers. It is rare for a hermit crab to hunt and attack prey. This is especially prevalent in hermit crabs that live in fish tanks. Most crustaceans suitable for such a life are smaller than fish.
This makes it unlikely that hermit crabs will attack your fish. As we will discuss shortly, these crustaceans will prefer to eat algae and plant life. These essentially act as the janitors of an aquarium.
It is likelier that fish will attack hermit crabs. The hermit crabs suitable for tank life are small and meek. This could make them easy pickings for a hungry or aggressive fish. Pair your species carefully. We will profile fish that are good tankmates for hermit crabs shortly.
What Are The Advantages of Keeping Fish with Hermit Crabs?
There are advantages of placing hermit crabs in a fish tank. These animals are aesthetically pleasing, entertain fish, and keep an aquarium clean.
One of the best things about owning an aquarium is aesthetic splendor. It’s relaxing to sit and watch a fish tank, especially if populated with tropical marine life. Hermit crabs can add even more color and pizzazz to an aquarium.
Hermit crab shells can be chosen. Offer a selection of brightly-colored shells to your crustaceans. They will choose whichever shell serves their needs best. Some hermit crabs may even change shells multiple times in a week.
Many breeds of hermit crab look striking anyway, though. The electric blue or electric orange hermit crabs, for example, will brighten any aquarium. Some well-chosen and compatible breeds can create all the colors of the rainbow in your tank.
Obviously, decoration is not reason enough to place hermit crabs in a fish tank. These complex creatures still require appropriate care. All the same, their arresting appearance is a welcome addition.
Hermit crabs are tireless cleaners of an aquarium. In lieu of scavenging carcasses, they eat algae and fungi. Hermit crabs often work in tandem with cleaning shrimp. Hermit crabs will even eat fish feces, as well as their own waste.
What’s more, hermit crabs are drawn to new, novel food sources. As a result, hermit crabs may eat dead fish that sink to the bottom of the tank. The crustacean may come into conflict with surviving fish for this meal. Overall, it can be an efficient process.
Alas, the cause of death may make a hermit crab unwell. As per The Biological Bulletin, hermit crabs learn to avoid foods that cause ill health. All the same, it’s worth keeping an eye on your hermit crabs.
Hermit crabs provide entertainment for fish, and vice versa. Both fish and hermit crabs are curious. They like to explore their surroundings and encounter new discoveries.
Life can be quite dull in a tank for underwater animals. This is especially prominent in tropical marine life. These fish or crabs are used to swimming free, encountering other wildlife. Pairing these two species will replicate wild living as much as possible.
By pairing up these two animals, both fish and hermit crab will have company and entertainment. You may find that the fish and crustaceans ignore each other. That’s fine. Just knowing that each other is there is enough to reduce stress and increase stimulation.
What Are The Disadvantages of Pairing Fish with Hermit Crabs?
You cannot just drop hermit crabs into a fish tank and forget about them. Hermit crabs are living animals. They require just as much care and maintenance as your fish.
Before bringing hermit crabs into an aquatic home, consider whether you can meet their needs. Hermit crabs bring plenty to a fish tank, but they also create more work. There are a range of considerations at play.
Hermit crabs will eat any algae and detritus in an aquarium. They still need additional feeding, though. These dietary needs may differ from those of the fish in your tank.
Hermit crabs do enjoy fish flakes as treats. Research the dietary preferences of your breed of chosen hermit crab, though. You will likely need to add meat, seaweed, or vegetables. Ensure these are not harmful to the fish in your tank.
Do not go overboard on feeding hermit crabs, either. They are small and eat comparatively little. Uneaten food will rot, spoil, and impact water quality. Check that food is being consumed and perform regular spot cleaning to clear waste.
Just like their terrestrial counterparts, marine hermit crabs molt. This is the process of shedding an exoskeleton while a new one grows. Young hermit crabs under this process regularly. Older crustaceans will molt roughly every 18 months.
While a hermit crab is molting, it is vulnerable. This could lead to a hermit crab becoming a snack for an opportunistic fish. Ensure the hermit crab can burrow to safety. As per the Journal of Experimental Marine Biology and Ecology, hiding reduces mortality while molting.
If you understand signs that a hermit crab is set to molt, you can move it. Hermit crabs like to molt in peace. By setting up a second location, it can do so. In advance of molting, hermit crabs will:
- Become shy and lethargic
- Turn a duller color, usually gray
- Eat more than usual
- Burrow at every opportunity, as though building a new home underground
Acting before the molt begins protects crustaceans and fish alike. When a hermit crab molts, it discards a dead exoskeleton. This will be eaten by the hermit crab to provide calcium. The bad smell may upset fish, though. Moving the crustacean keeps everybody happy.
Space is always a concern for animals. Marine lifeforms are no exception. Ensure an aquarium is large enough to house both fish and hermit crabs. These crustaceans may be small, but they still require their own territory.
With fish and hermit crabs alike, bigger is better. Never consider a tank below 10 gallons in size. Ideally, double this. Go even bigger if you have space. The more room you have, the more marine animals you can add.
Allow at least 4 inches of substrate for burrowing. If sharing a tank with fish, consider upping this to 6 inches. Hermit crabs will look to burrow for peace and safety. The more substrate they have, without impending on swimming space for fish, the better.
You need to consider the substrate that lines the bottom of an aquarium. As mentioned, hermit crabs need the opportunity to burrow. This means that rocks and gravel are insufficient. A hermit crab needs something soft, ideally sand.
You can purchase sand for an aquarian from any pet shop. These will typically be colorful and expensive. They are designed with aesthetics in mind. In reality, play sand is ideal.
Just purchase sand that would be used to fill a child’s sandpit. This will be safe and suitable for your hermit crabs without harming fish. Just remember to change it regularly as part of your aquarium deep cleaning.
Fish That Can Live with Hermit Crabs
Not all fish can live with hermit crabs, and vice versa. You must ensure that you weigh up the pros and cons of inter-species living arrangements. Things to consider include:
- Water temperature
- Feeding schedules
- Animal temperaments
- Saltwater and freshwater needs
- Chemical level in the water
- Available space in the tank
If you can meet the needs of both species, consider which fish to keep. Some fish accompany hermit crabs better than others. Let’s review some of the best options for pairing fish with hermit crabs.
Hermit crabs and clownfish make natural tankmates. These 2 species co-exist peacefully in the ocean. They can replicate this relationship in captivity.
It is possible for clownfish to go grow aggressive. This typically happens when they change gender. Clownfish are born male and can choose to evolve into females. They will do this to become the dominant female in a school.
Even if this transpires, a clownfish will usually leave a hermit crab alone. Clownfish are only territorial toward fellow fish. As clownfish and hermit crabs enjoy similar living conditions, they will typically be fine together.
Damselfish have a similar temperament to clownfish. This can be both a blessing and a curse. It means they get along fine with hermit crabs but may attack other fish.
Damselfish are undeniably visually striking. If you wish to establish a hermit crab tank with fish, consider damselfish. This species is tough and hardy. It will flourish while you adjust to your new tank set-up.
Just be wary about adding more fish afterward. The damselfish is dominant and territorial. It may attack any interlopers. As with clownfish though, a damselfish is unlikely to show any interest in a hermit crab. The two species will each mind their own business.
Royal gramma fish are among the most visually impressive saltwater marine life out there. These fish are also completely docile. They are just as shy and peaceful as hermit crabs. The two species will rarely interact.
The only note of caution is shared seclusion. Royal gramma fish, like hermit crabs, like to hide. This means the two animals may invade each other’s territory. This can lead to conflict.
Overall, the royal gramma should be fine with hermit crabs. There is little reason for these two species to interact. They’ll both go about their business, helping an aquarium look stunning.
Colloquially known as, “gobies”, the Gobiidae family are often used as tankmates for hermit crabs. The firefish is arguably the most common example of this fish family. Gobies are generally docile and rarely attack hermit crabs.
Gobies and hermit crabs share a love of shells, though. Gobies like to build and reinforce walls around a den. This means the animals may come into conflict, albeit inadvertently. The gobie may grab what it believes to be an empty shell and drag it away.
These two species can live together harmoniously. Just ensure these are plenty of shells to go around. Allow for two or three for each fish and crustacean to minimize conflict.
Wrasses are bright fish that have a reputation for being cantankerous. They will certainly attack other fish that look similar. Hermit crabs and wrasses can live side by side without incident, though.
Just be mindful of the voracious appetite of the wrasse. These fish can be greedy. They will often attack and eat an exposed hermit crab. This is not an act of aggression. The fish just saw a snack and seized upon it.
You’ll be fine if your hermit crab can protect itself. Ensure the crabs are never left without shells for long. Provide plenty of options. Ensure your hermit crabs have enough substrate to burrow into hiding places, too.
The pajama cardinalfish is a beautiful and docile addition to any aquarium. Multiple pajama cardinalfish will live happily and peacefully together. They will also leave hermit crabs alone.
You could pair a pajama cardinalfish with any of the other fish we have discussed here. Just be aware that they may be bullied by more dominant species. This may lead to the pajama cardinalfish turning on hermit crabs.
It’s rare for the pajama cardinalfish to show interest in a crustacean. If muscled out of food, though, it may seek nourishment elsewhere. This could be an unsuspecting hermit crab. For the safety of all aquarium inhabitants, consider pairing these fish with gentle equally breeds.
Guppies should be approached with a little caution. These are freshwater fish by nature. They can tolerate a little saltwater, though. This means they can live alongside hermit crabs.
While there are undeniably better choices, guppies are ideal for smaller tanks. The diminutive size of these fish and dwarf hermit crabs takes up little space. Guppies are also low maintenance to care for.
Perhaps most importantly, guppies are just as gentle as hermit crabs. The two species are unlikely to cause each other any concern. Just be wary of larger hermit crabs. A more aggressive and confident crustacean may attack a curious guppy that explores the substrate.
The cleaner shrimp is a crustacean that acts as a tank cleaner. Cleaner shrimp eat algae and debris in an aquarium.
This does not mean that you need to make an either/or choice, though. An aquarium should be big enough for both species. It’s rare for cleaner shrimp and hermit crabs to fight. As long as both animals have their own hiding places, they’ll be fine.
Cleaner shrimp will certainly fare better than sea snails. A hermit crab may attack these aquatic animals to steal their shell. Cleaner shrimp have no shell to offer. They are also fast and nimble enough to dodge pincers.
Fish That Shouldn’t Live with Hermit Crabs
While many species of fish peacefully co-exist with hermit crabs, this does not apply to all. Some of the most popular pet fish and incompatible with hermit crabs. This must be taken under advisement before pairing species.
The goldfish is among the most popular aquatic pets in America. Hermit crabs and goldfish should not live together, though. Both species have unique needs, and rarely cross over.
Water is the biggest issue. Goldfish do not flourish in saltwater, while hermit crabs need this. In addition, goldfish like cooler water than hermit crabs. It is almost impossible to find a mutually satisfying living arrangement.
Betta fish are among the most popular tropical fish in the world. They look stunning and bring any aquarium to life. Can hermit crabs live with betta fish, though? The answer is usually no.
Consider the other name for bettas – Siamese fighting fish. These are not shy and retiring fish. They can be aggressive. This means a betta may attack a hermit crab. This will cause stress to the crustacean.
It can also be dangerous for the fish. If provoked, the hermit crab may fight back. An adult hermit crab can slice a betta into two with its pincers. For the safety of all parties, keep bettas and hermit crabs in separate aquariums.
Bettas have a reputation as aggressive fish, but they are shrinking violets compared to cichlids. These brightly-colored fish look great. They are hugely territorial and constantly battle for dominance and territory.
If a cichlid has seen off competition, it will quickly turn its attention to hermit crabs. This fish is large enough to attack and eat a hermit crab. Your crustaceans are unlikely to survive long with these tankmates.
Can Hermit Crabs Live in a Pond?
The primary concern is one of temperature. Unless you are going to heat a pond permanently, you cannot control water temperature. In the winter, your pond water will drop sharply in temperature. It may even freeze over.
This fine for common pond fish, such as carp. These fish enter a state of torpor, remaining motionless until temperatures increase. This is not an option for hermit crabs. These crustaceans will die exposed to regularly temperatures below 50 degrees Fahrenheit.
Consider the safety of your hermit crabs, too. As mentioned, hermit crabs can be a fish snack. The larger the fish, the likelier this is. Bigger fish, like the carp, will make short work of hermit crabs.
It can also be tough to provide sufficient shells in a pond setting. Hermit crabs constantly molt and seek enhanced protection through shells. If these are floating free, the crustacean will struggle to safely make use of them.
This will also force your hermit crab closer to the surface of the water. This is not a hermit crab’s natural territory. It may find itself submerged on dry land. If not picked off by a swooping bird, a marine hermit crab will suffocate. Keep your crabs to a fish tank, not a pond.
Marine hermit crabs can live with fish. In fact, this can be a mutually beneficial arrangement for all involved. Hermit crabs will keep a fish tank clean, eat well, and add character to an aquarium. Just ensure the species of fish and crustacean are compatible, and all are cared for appropriately.