sudden carnage

[dfepeman]

I have a pair of wild perculas that have lived together for almost a year- one was from an original mated pair and when the mate died I introduced another ( a bit smaller- they are both only 2-3"). They seemed to get along and didn't seem to have any battles except mild ones occasionally. They share a hammer coral and seem quite fine together.

Last week I got an emerald crab to try to control some bubble algae- that and a new coral gobie and some more scarlet hermits are the only new occupants.

Well, tonight I come home and one of the perculas (the larger, more dominant one) is all torn up: most of the tail is missing and the dorsal as well; she is staying down in a secluded corner looking very bad- I don't think she'll make it. The other is still hanging out in the hammer coral, but also has some chunks missing from his tail and dorsal. He visits the other one and doesn't seem aggresive.

So, the question I have is: Did the small emerald crab (3/4", perhaps; seems juvenile) do this, or did they suddenly have the mother of all battles after living in harmony for over a year?

It is so sad to see them now- they were doing so well!

[Wolverine]

My first bet would be the emerald crab.
Which of the "coral gobies" do you have? There are several species which go by that name.

You said those animals were the only "new" ones. What are the "old" inhabitants of the tank?

Dave

[hrrsncrg]

When I first introduced my emerald crabs they beat up my clowns as well but eventually moved on.

I have no proof but from my experience the clown healed fine. I also dose my tank once a week with Lugol's solution. If you don't already I would begin dosing w/Lugols. It stimulates healing and keeps everyone in the reef happy.

craig

[traveller7]

I would not discard the concept of a disease entering the tank with the new additions either. I would not expect an emerald crab that size to get to 2 clowns in short order unless they were in a weakened condition.

As Wolverine asked, what are the other inhabitants?

[Juck]

My money's on the crab. Here's a picture of one eating my firefish,,, he got through 3 or 4 damsels as well.

http://reefcentral.com/gallery/data/500/50355crab.jpg

[stykthyn]

my vote is for the crab as well.

[dfepeman]

Sorry, I didn't get enough info. The other new inhabitant is sometimes called a "pink gobie"; don't have my books handy to give the proper name (has some nice diagonal maroon stripes). I haven't seen him since I added him to the tank, like other shy gobies I've put in. Doubt he's a predator. The other inhabitants in my 90 gal tank are a blue tang, a foxface rabbitfish, 6 green chromis, target mandarin, hectori goby, bicolor blennie, a green gobie, another greenstriped goby that hangs out in the acropora, 2 skunk shrimp, and 2 peppermint shrimp.

I don't suspect disease, since the sudden shredding of fins doesn't fit. I don't think the other fish are to blame- they are generally peaceful.

This morning the badly beaten up clown is gone, thanks apparently to the clean-up crew, etc. The other is hanging out in the hammer coral. If he heals up okay, maybe the emerald wasn't to blame (or he had one psychotic killing spree; hard to believe).

I had avoided adding crabs for all the stories of aggresion I've heard, though they are usually for mature crabs. I caved in to the LFS owner's assurance that the emerald wouldn't be a bother, but I am surprised if it is the culprit being so small.

That being said, I don't want to take chances. How can one catch an emerald crab? I hear it is a nightmare. I could put him in my sump, perhaps.

[boomsticks]

Emerald Crabs wouldn't attack a clown, at least not in my experiences. Well you never know, but I think people give crabs an awful rep even though they themselves never had a bad experience with them. I am partial to lobsters though. I think they are fascinating, crabs are just more of a pain (knocking over stuff) but reletivly harmless....well some are....

[Wolverine]

<a href=showthread.php?s=&postid=7429473#post7429473 target=_blank>Originally posted</a> by boomsticks
Emerald Crabs wouldn't attack a clown, at least not in my experiences. Well you never know, but I think people give crabs an awful rep even though they themselves never had a bad experience with them. I am partial to lobsters though. I think they are fascinating, crabs are just more of a pain (knocking over stuff) but reletivly harmless....well some are....

I've witnessed emerald crabs going after fish.

After seeing what else is in the tank, I'm changing my vote to the chromis (or at least one of them). Remember, they're damsels. Bicolor blennies can also be pretty destructive, but that's usually more towards other blennies.

Dave

[podder]

All this over bubble algae! =\

Perhpas the moral of this story is to resist adding "something" to your tank in hopes of it "removing" something from it. Too many people believe the answer to "X" is something that will eat it.

Yes mithrax are known to eat sick and/or unsuspecting fish. After all they are not obligate bubble-algae eaters!

Hope your fish recover!

[dfepeman]

Well, the remaining clown seems to be doing just fine. No one considers that this might have been a long-delayed battle between the two perculas?

I add things to my tank quite slowly, so my suspicion about the emerald crab might just be coincidence- any change to a tank might alter the behavior, but if it was clown warfare it is remarkable that they did it after so long living as juvenile buddies. That and the fact that the one I thought was smaller and most likely to be the male winning the fight.

I think it is still a mystery, so I'll be watching things closely.

[dfepeman]

Oh, and about adding things to fix a problem: My foxface was introduced to take care of a macroalgae infestation, and that worked out great. Sometimes the meddling with nature works :)

[Wolverine]

<a href=showthread.php?s=&postid=7437414#post7437414 target=_blank>Originally posted</a> by dfepeman
Well, the remaining clown seems to be doing just fine. No one considers that this might have been a long-delayed battle between the two perculas?


Not too likely. Usually if they're going to really go at it, it's early on, before they've established who's going to be the female. IME the real fighting only last a few days in perculas and ocellaris, and they don't tend to do too much damage if there are only two of them.

Dave