Any crabs that are just plain too slow to hurt fish? Don't have to be reef safe.

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Betta132

New member
I've been looking around a bit, and I've found pictures of hitch-hiker crabs that are identified as being not reef safe... But some of them are plump and have these thick claws with only a bit of claw and a lot of muscle. Those guys can't move THAT fast...
Are there any crabs that are considered bad because they eat corals and such but are too slow to catch fish? Now, I don't want somebody who's going to try to eat sleeping fish, or somebody who's going to be constantly scaring them. I'm thinking more along the lines of somebody who's just too slow to be interested in fish... I don't care if he'd try to keep corals, I can leave those out.
It would also have to be somebody who's not gonna be breaking my turtle grass, though.

Are purse crabs fish-killers? They're sure neat.
 
Bottom line...all crabs are opportunistic ominvores. Given the chance any crab can catch a sleeping fish.
 
Well, other than little porcelains. Those guys have claws that don't even work all that well.
Darn. Guess I'll just have to stick to meanie crabs in the sump.
 
Acros won't hurt anything. Pom pom crabs are pretty safe as well.. too tiny to do anything.

As far as something bulky..
Calappidae species are just bulldozers, their claws are built specifically for bivalves and snails (one is hooked while the other is normal), They will consume frozen food of course so nothing diet specific.. but they won't be targeting fish even when hungry. I can guarentee this with calappa calappa as they're pretty stiff like a horseshoe crab with very tiny claws, but the others seem more flexible so I can't 100% say for certain..

However like I said, they're bulldozers, in a tank filled with rock or stuff in the sand it's doomed to be knocked over or pushed to the side.

Good luck finding one though, I've seen calappa calappa only twice available, both which I snagged ;) (Unforunantly both didn't live either.. first one I lost in a tank crash and the second didn't survive shipping)
 
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Oh yeah, PomPoms are awesome little guys to watch.

I avoid any other type of crabs besides whats mentioned.
 
I like pompoms, but I've always been a bit concerned that they'd end up stinging something... Do they sting things with their anemones? I have a damsel who likes to tail-whap new additions, and I don't want the little spazz getting himself stung up.
 
Acro crabs are very neat and they just sit in their coral, so they are visible but won't be wandering around looking for a neighbor to eat.
 
Betta132 said:
I like pompoms, but I've always been a bit concerned that they'd end up stinging something... Do they sting things with their anemones? I have a damsel who likes to tail-whap new additions, and I don't want the little spazz getting himself stung up.
Click to expand...

Nah, they wouldn't hurt anything. Also remember clownfish are damsels so they have the anemone resistance too.

Reguarding coral, they're not potent enough to do much damage. The pom pom usually will keep it's distance from coral for the anemone's safety.

One problem with the pom pom however is they are VERY VERY shy.. I've had times where mine disappeared for 3 months!! They're also very skiddish.. walk up to the tank and inside a rock they go. They're best in small nanos where you can see them better.
 
Good points on the acro and pom pom crabs. My mind went to typical larger species crabs since he mentioned hitchhiker crabs.
 
PomPoms pretty much use the anemomes on their hands to capture floating food. I usually see them run up the tops of the rocks waiving their pompom to capture brine or mysis I feed them. Mine when I had them where always out. Would wave their pompoms in front to tell the fish don't even think about it , then continue on their business.
 
I haven't kept many crabs, but what I have kept (other than hermit crabs which are always safe unless the fish is dead or has no chance at living), Emerald crabs are the way to go. They're reef safe if you ever go that route, and they eat lots of algae. Sally light footed crabs are good when they're small, but when they get big they become a problem. The other crab I've had, which isn't even a crab at all, is the horseshoe crab. Many people denounce it because it grows to large, but I've had mine for 6 years and it's gone from the minuscule size of 1 inch to the estonishing 2 inches. So not really a problem there. They are extremely fast but never hurt your fish, but will eat corals. They are a thrill to watch swim around your tank and i garantee you'll love them. They also get along with just about every fish, crab, shrimp, snail, etc... Everything there is except for corals
 
Oh and also all the crabs are very easy to care for and will just eat algae (except the horseshoe crab) until it's gone and then they will take anything you give them. All super hardy. They are all currently living in my 75 non reef tank happy as can be. They were the only survivors of my tank crash 2 months ago just to prove the point. I hoped i helped! And you can get Emerald in red and green
 
Emerald crabs are known to sometimes eat fish if they get hungry. Not risking it. Plus, it's a macroalgae tank, I don't want a plant-eater crawling around in there.
Sally lightfoot crabs are notorious fish-eaters, they move far too fast, they're hard to catch, and they actually have claws made to grab and kill things.
Horseshoe crabs are doomed to eventually die of starvation. One growing that slowly is probably not getting enough food or has something else wrong, they grow quite a bit faster in the wild. There should be a noticeable size change every molt and a molt several times a year. A horseshoe crab is supposed to reach adult size in about 8-10 years.
 
peasofme said:
things are going to grow bigger in the ocean than in a tank
Click to expand...

That mainly depends on the animal's food supply in captivity. Some fish do grow larger in the wild but they also have a larger abundance of food to keep up with their natural growth rate.
 
Eh well I've had no problems I know the Sally lightfoot aren't that safe but the horseshoe crab still seems pretty good and I just can't se an emerald crab being able to catch any fish that wasn't already so sick it didn't have a chance at life anymore. I have 3 with a mandarin, and if they can't catch that they won't be able to catch anything else
 
Horseshoe crabs shouldn't even be collected. They WILL starve in home aquariums. They live on the food found in the sandbed, which they quickly diminish. Not to mention an over a foot diameter crab is one big mouth to feed.
 
I have had two emeralds. First one took 6 hermits in one night. The second constantly worked on bubble algae. Unfortunately since he was the only new inhabitant I am assuming she was also what took my healthy firefish and attacked my lubbocks fairy wrasse. I caught and dumped her and have had no issues since.
 
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