What is this thing

Dsturgeon · Jul 4, 2018

Ok I’m new here, I have been 3months in cycling my tank, and last week I started adding crabs and snails etc, then fish this week.

Seen this little fella hiding out of a bit of rock. At first I thought it was algae but I watch the spot for 20mins and he has eyes and does move a bit.

Please help

HotRocks · Jul 4, 2018

Welcome to R2R!

Can you describe exactly what in the pic we are looking for?

Let's see if the #reefsquad can help!

KJ · Jul 4, 2018

Remove them.

TexasTodd · Jul 4, 2018

BAD crab. Remove to sump.

Dsnakes · Jul 4, 2018

Some sort of hairy crab?

Maritimer · Jul 4, 2018

That's a crab that tends to live in Acropora and other SPS corals. I had two of them, but had to delete one (the smaller) for chewing on my green slimer. The larger one lives in a birdsnest, and _so_far_ hasn't caused a lot of trouble - but I'm keeping an eye on him.

~Bruce

Lasse · Jul 4, 2018

Looks like a hairy crab - but can anyone explain for me that they always will be seen as unwanted in a reef aquaria - just because it is hairy. This guy that you can see in the beginning show up after 5 years in my old aquarium - a teddy bear crab. And he/she was not a small crab - just look at the spectator at the right side of the video. It did never harm anything in my aquarium - moving rocks - yes but eating anything - no

Sincerely Lasse

KJ · Jul 4, 2018

Cymo Andreossyi acro crab.

Lasse · Jul 4, 2018

Maritimer said:
That's a crab that tends to live in Acropora and other SPS corals. I had two of them, but had to delete one (the smaller) for chewing on my green slimer. The larger one lives in a birdsnest, and _so_far_ hasn't caused a lot of trouble - but I'm keeping an eye on him.

~Bruce

Did you actually see that the crab was damaging your green slimer? My Sally Lightfoot (and its big) often sitt in the centrum of my corals - cheving a lot on them but never ever I have seen any damage to the corals afterwards - it is like it clean them instead.

Sincerely Lasse

Gerald Garcia · Jul 4, 2018

Dsturgeon said:
Ok I’m new here, I have been 3months in cycling my tank, and last week I started adding crabs and snails etc, then fish this week.

Seen this little fella hiding out of a bit of rock. At first I thought it was algae but I watch the spot for 20mins and he has eyes and does move a bit.

Please help

Hi! For one... I hope it's not a gorilla crab. Take another pic of you can. If the claws are black... it just might be. The stone crab are also known as Teddy bear crabs.

There are several different "teddy bear crabs" and it's hard to tell them apart because of all that fur! But this one looks like a Pilumnus, in the family Xanthidae.

They're general omnivores and will eat anything they can catch. Several xanthids are known to be poisonous because they eat zoanthids & retain the toxin produced by the zoanthids for their own defense.

Lasse · Jul 4, 2018

And @Dsturgeon
Welcome to R2R !!

Sincerely Lasse

Diesel · Jul 4, 2018

Gorilla crab

kill them fast, hard and twice to make sure they are history

ThunderGoose · Jul 4, 2018

I'm with @Lasse , not all crabs are evil. BUT there are thousands of species that could show up in a tank, many of them with little or no information available. I have enjoyed watching the little crabs in my nano tank. No identification on most of them and, once I pulled out the red mithrax, no obvious damage to corals.

TexasTodd · Jul 4, 2018

I'd sure keep an eye on it. Generally hairy legs is suspect. All the Acro crabs I've ever seen are not hairy like this one. Mithrax aren't hairy either. Sally will eat fish sometimes but I've never had them eat corals.

Maritimer · Jul 4, 2018

Lasse said:
Did you actually see that the crab was damaging your green slimer? My Sally Lightfoot (and its big) often sitt in the centrum of my corals - cheving a lot on them but never ever I have seen any damage to the corals afterwards - it is like it clean them instead.

Sincerely Lasse

The slimer was being damaged on the branches where the crab was hanging out, so I dropped the crab into my sump. A week and a half later, the slimer had healed somewhat, and the crab had found its way through my return pump (pretty big impeller...), but landed at the other end of my 220 gallon display. Two weeks after that, the crab had crossed the tank to return to the slimer - and once again, the branches where it was living were turning white and ragged-looking.

Circumstantial evidence, but pretty convincing circumstantial evidence . . .

~Bruce

Dsturgeon · Jul 5, 2018

Thanks everyone for your reply’s and the welcome I’ll see if I can get a few better pic close up as you zoom the quality demishes.

I notice this guy appearing about a week or so after the Sally Lightfoot was added to the tank, possible hitchhiker from the crab??

Dsturgeon · Jul 5, 2018

He has a dark brown/ Black body, hides under the fuzz he has. He doesn’t move from that one piece of rock. Somewhat defends it from the snails which is funny considering the size of him