Acro Crabs: Good or Bad?

[BiochemRobyn]

Are these little guys bad?

It turns out that there is an 5mm albino acro crab on my pink mille colony. Although he doesn't seem to do any harm, I'm concerned about the long-term prospects of having him in my tank. After a hitchiker crab decided to eat one of my seahorses, I vowed that I would never let another crab slip by me again alive. Yet I couldn't imagine this guy doing any harm until he gets big enough to waddle on to some other coral.

Any thoughts? Is it better to bite the bullet and kill him now?

[hypertech]

Good, and if you don't want him, I'll take him from you happily.

[Redwinger]

No don't kill him. These are worth more than gold. I still am going with my theory that these acro crabs eat aefw.

[morty]

I've read the smooth ones are harmless if not good, but the hairy ones (gorilla crabs) are the bad guys.

[BiochemRobyn]

I've read the smooth ones are harmless if not good, but the hairy ones (gorilla crabs) are the bad guys.

This guy is definitely smooth.

How large to the gorilla crabs get? We once saw a 3-4" extremely hairy crab in Nam's tank, but we haven't seen him since. He seemed to be nocturnal. Could he be one of them?

[BiochemRobyn]

No don't kill him. These are worth more than gold. I still am going with my theory that these acro crabs eat aefw.

What do they eat in the meantime? I don't believe that I have any aefw problems. He does seems to feed when I put mysis in the tank, but I can't be sure.

[coralreefer]

Have you seen blue planet? They show one attacking and warding off a crown of thorns starfish. The only coral in the vicinity that survived was the one with the acro crab. I have one in my stylophora and it hasn't done any harm for over 2 years. It never leaves the coral either.

[hypertech]

The one in our big acro doesn't leave it. He may catch a mysis every now and then. I've also heard they may feed off of mucus and other stuff they clean off the coral.

[mattb]

Blue-eyed hairy tend to be bad....

Why would a symbiont abandon the benefits of the relationship? The acro crabs eat a lot of stuff, mucus, probably not, but since corals have bacteria all over them, and some corals even farm bacteria for consumption, this is most likely the goods the crabs eat....

John, I've heard that some may eat aefw... I've had a couple of colonies that had both :(... I don't think it's also as simple as blue-eyed hairy ones are bad either... A lot of the maricultured (grown out in the ocean, not in tanks), have a TON of crabs that come in on them, I remember pulling nearly a dozen off a couple of mille colonies. They are the hairy blue-eyed ones... Is it something about captivity? Not enough food? It's not like these colonies were showing the signs that they were eating them either - flawless colonies...

[BiochemRobyn]

Why would a symbiont abandon the benefits of the relationship?


Sounds like the little guy will get to stay :biggrin:

Thanks for all of your input guys!

[David Grigor]

There good but impossible to get out of the colony and if you ever treat for red bugs they will be history......

[spsick]

Usually they are good but I have seen them irritate acro's to death before.

[gogregerson]

It's very Bad, you need to get it out of your tank right now.....and into my tank lol In all seriousness just keep an eye on it. The nice thing is, it's not going anywhere. If the colony starts to suffer pull it out.

[spectrum]

The one in our big acro doesn't leave it. He may catch a mysis every now and then. I've also heard they may feed off of mucus and other stuff they clean off the coral.

Thats what my book "Reef Secrets" says about them.

[morty]

There good but impossible to get out of the colony and if you ever treat for red bugs they will be history......

I was actually able to get one out of my colony before doing a dip by chasing it down to the base of the coral with a plastic stick and then blowing it off the base into a bucket of water with a strong puff of air :)

[hypertech]

Some of the stuff we do has got to just make people shake their heads.

Chasing little crabs around, setting traps with strings, I've even heard of people fishing in their tanks.

[morty]

I've even heard of people fishing in their tanks.

:gay1: A while back I bought the smallest hooks Gander Mountain had in their fly fishing section, and some ultra tiny weights and thin line, in preparation to catch an evil Sohol tang out of my tank. I caught him with a net instead, but I have the hook and line for emergency use later on if I need it.

We need a new thread - "oddest things we've done for our reef hobby".