Disappearing fish.
 

Hello all,

So... I have a 29 gallon tank, assortment of Zoos and LPS corals. I've had fish randomly dissapear over the last 1.5 yrs... and it's really beginning to irk me. So far have lost a firefish blenny, a lawnmower blenny, and one clown (he just died though... about 3 yrs old.... poor guy). The other two I never saw again. Shrimp don't seem to last long either.

I know the usual suspect is a Mantis.... but I have never seen one, never heard one, have put out traps... and nothing.
I do have some biggish emerald crabs.... could they do it? Rawr. I miss my fish!

large emerald crabs can prey on small fish, especially if ther are hungry or develop a taste for meat, I've g=had ti remove several large emeralds from my tank for that problem. don't underestimate a mantis though, they're sneaky buggers

My guess is that your fish died and the crab ate it. Shrimp usualy die and decompose. I had 3 fire shrimp that died without much trace. 2 killed eath other and soon after died. One was missing all of its legs from the battle. The other remaining lived for another 6 months and died, then was eaten by the little crabs in my tank. Small fish especialy can be consumed fast.

I think a mantis would need to eat quite a bit more than 2 fishes in a 1.5 year. You already know the clown died, the rest probably did the same. Most fish tend to hide when they are sick and probably die when hiding.

I've lost a few fish, and I've Never seen a dead body. I know I had a huge crab in the back of my tank before (body was the size of an egg, round like an egg too). Around where he hides is a graveyard of snail/conch shells too.

Thankfully I think he kicked the bucket now too, as I've put more snails in the system, and they're all accounted for.

If you can find it, catch the crab and put it in your sump!

IMO if a small fish or shrimp dies and you find much more than a skeleton after a day or two, you should re-evaluate your cuc.

A good clean up crew will take care of a small fish after it's demise.

Huh. Well, thanks for the input.
I'm pretty sure my fish aren't just randomly dying, I've never had a problem with water chemistry.... and the other fish are completely healthy. Even the clown was perfectly happy and eating, and then I just found him dead the next morning. The others just vanish, but right up to that point are active, and eating. Hrmphh.

Once again I am left to ponder the mysteries of nature.

What other fish do you keep? Anything that could potentially be killing or eating your disappearing fish?

Hey there,

Well not much that I can think of. One remaining clownfish, and then a dwarf angelfish. Cleanup crew is comprised of Nassairus Snails, Turbo and Astrea snails, and a few hermit crabs (quite small ones). Also 1, possibly 2 emerald crabs, about the size of a toonie. Thats about it, just some smallish bristleworms.

Thanks again!

I know how you feel , I have lost 3 gobies . no sign of a corpse , 1 day eating fine next day gone . I have something snapping in my tank but I think it is a pistol. pretty frustrating

Hehe I know what you mean.... if anything, owning a reef tank has demonstrated that life is not nearly as happy 'Under the Sea' as Sebastian the crab would have you believe. Everything is trying to kill everything else. Still love that song though.

R.I.P.
 

So the other day I was reaching around the back of my tank to get some rubble for mounting frags... I felt something very smooth back there, and pulled it out... I nearly dropped it cuz my hand was shaking so bad out of shock/fear!

https://lh6.googleusercontent.com/_1.../s800/CRAB.JPG

THE BIG BAD CRAB IS DEAD!!! No wonder all the snails I recently bought are still around!!! This shell is huge! About 3 inches across!! It reminds me of The Predator :S But I was so relieved that it's gone! Now I wont have to worry about my inverts, and I can get more if I wanted!

Wow you win the "I'm never sticking my hand in the live rock again' award for sure. That thing is enormous. Are you sure it is off to the great big reef in the sky, or did it just shed? I'm pretty sure they shed. Just in case. Wouldn't want you to go out and but a bunch of really expensive food for that beast.

It looks like the Rancor from return of the Jedi.

WOW.
 

Thats awsome! I have caught about 10 BAD crabs in my tank over the last 6 months on a mission to rid my tank of them. I have 10+ snail shells missing snails so something is still eating them.

Crap, the molt too? Hmmerz... This shell felt pretty hard. Arent molted shells usually softer..? Well I'll continue to keep an eye on my snails for now. It's been at least 3 weeks, and they're still accounted for. And I havent see the big bad crab in at least a month...

BUT, I did see something strange the other morning. It looked like a long oval shaped creature, with legs at the front and back (almost like an underwater cockroach). It slowly crawled out from under a rock, and slid behind another rock. (and I didnt have a flashlight on hand!) I also noticed the rocks in that area slowly rose up, then fell back down one day. So something is definitely lurking in that area...

lol it amazes me what you can find in a tank that you never put there to begin with :wink:

looks like a moult to me & the cockroach like critter sounds like a mantis shrimp .

I think the fish need to eat a lot of praying mantis more than 2 to 1.5 years. You already know the clown died, the rest may be the same. Most fish are often hidden in their illness may die when hiding.

I can relate!! I lost a small dottyback to something hiding in my LR. And I think my new firefish might be the next victim. :sad: Ive checked the rock, but havent found anything, guess the only thing to do is set another trap and take another look.