Hey guys. I just bought this acro from my LFS and it came with 3(!!!) different crabs, each a different species. This album has the pictures https://imgur.com/a/5b3LK. One of them is kind of hairy. I don't want to write it off as a gorilla crab without a fair trial though. The last one is a tetralia, I know that, and I've put him in the tank with the coral. I used a paper clip to force the other 2 out of the coral until they get appropriately ID'd. For the moment they have an airstone. Also, the coral wasn't properly ID'd at the store, just kind of sold as "acro". If you happen to know what it is I'd like to know as well. Thanks!
Got 3 Acro Crabs on my new purchase, can I get an ID?
- Thread starter NeiDan
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Cary Meredith
Active Member
Can we say you got crabs 
lol not good if they eat them, lots of ones can be good though, these don't look like it
lol not good if they eat them, lots of ones can be good though, these don't look like it
Vaughn17
Well-Known Member
Same here. Recently found three hairy blue eyed crabs on maricultured colonies, gave all three a chance, and all three munched on the coral. The colonies recovered quickly once the crabs were removed.
All right so the Cymo andreossyi, or blue eye crab, seems to munch on polyps but also cleans the coral and protects it. It's generally considered symbiotic in the wild, but given the size of my colony I'm not sure I'm comfortable with it munching, so he's definitely going in with the mantis shrimp. The first one is giving me some trouble though, let me know if you need another picture of him. Based on the way he was camoflaged and the shape of him I want to say he's symbiotic, but I don't want to assume.
If you dont feed your acro crabs, they eat the coral. I believe the hairy one prey's on the acros crabs(because I only have 2 acro crabs now)
do you have a large stylo colony? mine migrate.... across the tank.
more than likely the outcome. My Pink stylo they came in on and green stylo are both like softball's
filbie70
Valuable Member
I banished my hairy blue eyed after he munched on my acro. From what I read they don't kill the coral in the wild because the coral out grows the rate which they feed. Not so on a 3" frag. Although, I did not sentence mine to a Mantis..gulp...he was banished to my sump. The little white one in the 3rd pic, takes good care of my Acros that he lives in.
Vaughn17
Well-Known Member
I fed mine, Salty. They still ate coral.
Vaughn17
Well-Known Member
They are commensal acropora crabs not symbiotic.
Strictly speaking symbiosis can refer to any 2 species that form a close relationship with eachother which includes commensalism, mutualism and parastism. In commensalism only 1 species benefits, while the other is largely unaffected. Mutualism is a synonym with symbiosis (which can refer to the whole range of interactions or just mutualism, depending on who you talk to) and refers to both species gaining something. In this case the acro crab does cause harm, which might point to parasitism, but it also protects and cleans the coral, which is mutualistic. You could make decent case for it being commensalism or mutualism IMO.
Vaughn17
Well-Known Member
Yes, I am familiar with the meaning of symbiosis. Careless error on my part. Typing without engaging my brain.
Crabs from the Xanthidae family have been implicated in the destruction of wild colonies of acropora that have high densities of the crabs. Whether they were behaving parasitically or the coral was unhealthy and they were just being opportunistic is reputedly unknown. IME, in a glass box, I would categorize hairy brown, blued-eyed acro crabs as parasites.
I have one other acro crab, presumably from the family Trapeziidae, that has caused no harm.
Crabs from the Xanthidae family have been implicated in the destruction of wild colonies of acropora that have high densities of the crabs. Whether they were behaving parasitically or the coral was unhealthy and they were just being opportunistic is reputedly unknown. IME, in a glass box, I would categorize hairy brown, blued-eyed acro crabs as parasites.
I have one other acro crab, presumably from the family Trapeziidae, that has caused no harm.
I would definitely agree that it would be closer to paratisism in a closed system like this. I sent a few pictures to the guys at Wet Web Media and asked them what they thought and they're response was to let the last crab in with the colony, so that's what I did.
Vaughn17
Well-Known Member
Also, I noticed that the three Xanthidae crabs stayed in the same spot for days and did not appear to be cleaning the acro colonies, while the Trapeziidae crab is constantly moving around in its colony. The Xanthidae crabs also moved around to other acro colonies. Two of mine did significant damage, so I would watch yours. Maybe he will be fine.
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