When setting up your reef tank, live rock is a very nice looking rock and keeps your aquarium healthy. Live rock can also harbor many types of visitors: some good and some bad. They are called hitchhikers. One common hitchhiker is Gorilla Crabs. They are known as the “killer hitchhiker” because they will eat your fish, coral, snails, and other small animals in your tank.
Keep reading to find all about Gorilla crabs and what to do if you find one in your marine aquarium!
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What Are Gorilla Crabs?
Gorilla Crab is a member of the family Xanthidae. The family Xanthidae is very diverse. To date, Xanthid crabs are the most species-rich family of crabs. There are more than 500 different species of Xathid crabs and possibly hundreds more waiting to be discovered.
They are called Gorilla Crabs because of their hair-like fuzz that covers their shells, legs, and claws. The number and color of hair will vary depending on the species. Some species may have hair on the whole body, or only on the claws, legs, or almost none. Hair color also varies from brown, tan or light green, muddy color.
Many species of Xanthid crabs are extremely poisonous, even when cooked. They not only kill fish but also cause human death. The concentration of tetrodotoxin in the muscles and egg masses is enough to kill you if you try to eat one.
Although they are very common, most gorilla and xanthid crabs are fairly ugly and not interesting enough, or even too poisonous, for aquarists to add to their tanks.
Why Are Gorilla Crabs Bad?
Some crab species are scavengers and detritivores. They will eat any leftovers food your fish missed or dead tissues. Seems like they’re your saltwater cleaning team when it comes to keeping things looking tidy?
But the Xanthid and Gorilla Crabs wouldn’t be content with just eating scraps and leftovers. They grow quite large and are omnivores that will scavenge and eat anything they can find.
And then, Xanthid gorilla crab will wreak havoc on our reef aquariums. They can eat corals, invertebrates like shrimp, starfish, anemones, clams, even small and slow fish. Gorilla Crab are usually quite small but they can overpower anything else in their size range or even a little larger.
It can also be very difficult to remove them from the aquarium. Once the Gorilla Crab finds a hiding spot, they tend to stick to it, only coming out at night. If you try to catch them, they will run away into the hiding spot.
How Do You Remove A Gorilla Crab?
There are not any fish or creature that can be added to the tank to remove Gorilla Crabs. You must do this yourself. Catching them by hand is the best option. But don’t take them by surprise or they’ll hide in a cave where you won’t be able to catch them.
Since they are nocturnal, the best time to catch them is when the lights in the tank is off. Once they show up, there are a few things you can do:
- Use a sharp stick to spear them.
- Set a crab trap. You can place a bottle with the top half cut off and upside down near the crab hiding place. Lure the crabs by putting some bait in it. The crab will fall inside and cannot climb out.
- Use nets to trap crabs. However, you have to be quick or they will startle and run away into hiding place
- If all of the above options don’t work, try the following. Remove all rocks from the tank and check every nook and cranny.
Keep in mind that if you found one Gorilla Crab, there may be more hiding in your own tank. Be sure to keep an eye out for rotters and other pests before they can cause any damage.
Some Other Ralated Questions
What do Gorilla crabs eat?
Gorilla crabs will eat anything they can get their claws on, including coral, small fish, starfish, shrimp, snails, and clams. It is not recommended to put a Gorilla Crab in your aquarium. These pests will prey on your fish and coral.
Are Gorilla Crabs reef-safe?
No. Gorilla Crabs are not reef-safe. Gorilla Crabs should be removed from your aquarium as soon as you spot one. They are pests that will eat anything they can get their claws on, including small fish, starfish, clams, and shrimp.
Are gorilla crabs poisonous to eat?
Gorilla crabs are highly poisonous, containing toxins which are not destroyed by cooking and for which no antidote is known. So you should not eat this crab even if you try it.
What are the difference between Gorilla Crab and Emerald Crab?
Gorilla Crabs and Emerald Crabs can be easily confused because they look similar, the difference is that Gorilla Crabs have black-tipped claws, while Emerald Crabs are entirely green. While Gorilla Crabs are not welcome, Emerald Crabs are safe to have in your tank. They can even be beneficial because they eat algae. Gorilla Crabs are not safe for your tank and should be removed.
It’s likely you’re dealing with a Gorilla Crab in your reef tank, one of the most irritating pests you can accidentally end up with… The creatures in the aquarium will not be safe when there are Gorilla crabs around. If you spot a Gorilla crab, you should get rid of them immediately
Annette M. Chaney is an experienced marine biologist with over 20 years of experience as an aquarist and fishkeeper. She started her first aquarium at a young age, filling it with frogs and goldfish obtained from the ten-cent pet store.
Annette grew up caring for and breeding African Cichlids, which led to a hobby in high school that doubled as a profitable means. Attending Reed College gave her time to solidify herself as an accomplished aquarium caretaker with an eye for sales. After that, from 2009 – 2013, she studied at Roger Williams University – one of the most prestigious universities for Aquaculture and Aquarium in USA. She is the founder of AquariumCircle since 2010