how to catch a crab/starfish??

[astroboy]

Hello,

 

I posted the message below a few days ago about what I thought was an aggressive PBT nibbling on some other fish. However, the more I think about it the more I think that the PBT might not be the problem. The PBT never really acts aggressively towards anything in the tank. I recalled before I got the tangs the wrasse showed up once or twice with a small piece of tail missing. At the time, I didn't think anything of it, but now I wonder if perhaps a crab or starfish didn't hitchhike in somehow. I QT everything, but a tiny crab could have hitchhiked in of course. 

 

The clowns, which sleep in a huge bubble coral, are always 100% intact, so that might explain why the crab isn't dining on them. You'd think a PBT might nibble on a clown sometimes, if it's going after the wrasse too.....

 

The PBT shows no damage, but perhaps it's too hard for the crab/starfish/?? to catch. 

 

However, both the yellow and hippo tangs have a lot of their tail and ventral and dorsal fins missing. Missing dorsal/ventral fins doesn't scream "PBT" to me. 

 

Any advice on how to catch the mystery guest, if there is one? 

 

Thanks,

 

Mark

 

 

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I have a 90 gallon tank with a couple of clowns, a six line wrasse, a yellow tang, and a hippo tang. The tangs are all about 3 inches long with fins, and were all introduced into the tank at the same time a few months ago.

 

Lately, the fins of the yellow tang have obviously been nibbled on. I haven't seen the powder blue tang acting aggressively, but I assume he's the bully. The wrasse and the hippo tang also show up with a piece of fin missing from time to time, no big deal, but I'm a little concerned about the yellow tang. 

 

I was wondering, would buying another yellow tang perhaps improve the situation, perhaps by dividing the powder blue's attention? Would it be likely to make it worse? As I understand it, yellow tangs are reasonably mellow, so having two in a 90 gallon, at least while they're still small, wouldn't be an issue. Is that correct?

 

Would something like a scopas tang help? 

 

Any suggestions on what to do about the powder blue acting like a hoodlum would be appreciated....

Edited March 8, 2015 by astroboy

[YHSublime]

I think it's a long shot that its a crab or starfish, it's most likely tang aggression. That being said, if you believe it's not, a pint glass with some food at an angle on the bottom of your tank will yield results come the morning.