what is eating my fish

a mantis would be much more likely to go after your cleanup crew, if its a smasher, only spearers take down fish, I don't think those are very common..
 
Seems like a lot of people have this same problem. Including me.

I have a 55 gallon reef and I had 2 firefish, a blue-striped goby, and a royal gramma disappear on me. Plus countless peppermint shrimp. I didn't really worry about it too much, since my mom lets her dog run around untended and I've had a few jumpers before (which I found before the dog). But recently with the mysterious disappearance of my beloved full 5" Blue Tang, my large Skunk Cleaner, and a large emerald crab, I'm getting suspicious. I also had a Coral Beauty that was fine one day and died the next, but unlike the others, I found the body untouched. I'm breaking down my tank this week for an upgrade, and hopefully find out what's behind it all.

Something I'd like to point out, though. All of the fish and inverts that I mentioned had a tendency to sleep hidden away in some crevice and often during the day as well. My tang, skunk cleaner, and crab were on and off behind the rocks, in front of the rocks, which might explain why they haven't been touched until recently. I have a clown that I've had since day one that's always out in the open and is still with me and a medium-sized algae blenny that does the same.

However, I've stayed up late with a red flashlight to see what I could find. I've seen a bristle worm, which I think might account for the shrimp, but for a large blue tang? I also saw some sort of brown worm, but only it's head. It looked pretty much like an earthworm and recoiled really quickly when I hit it with the light. I've read about a huge one taking out lots of coral, but a small one in a 55 taking out full-sized fish?
 
What about an anemone? My curly que helped itselt to a sailfin blenny. (burp) One day the blenny was there, next the anemone had a full tummy.
My green brittle star has been know to snitch fish too. What kind of seastars do you have?
 
I would imagine, other than an octopus, you should be able to find the culprit by digging through your rocks. Something that big shouldn't go unnoticed I would imagine. Though I'm sure by now you have already done that.

It sounds like whatever it is may be nocturnal. I'd sit up at night and occasionally spot around for it. Maybe try to bait it using some closed weighted container with some holes drilled into it. I'd try some frozen scallops, clam, or something that's cheap.
 
I recently found the remains of a fish I lost 4 months ago. It jumped out and landed (flopped) almost under my 44 gal brute trash can I use to store RO/DI water.

My other lost fish stories are overflows and crabs. The three mantis shrimps I had only took out my cleaning crew.
 
A few posibilities, depending on where your live rock is from:

-Carnivorous "cone snail" Be VERY careful if you see a snail with a cone shaped shell that has a "snout" protruding if it comes from the South Pacific. Some of these things are DEADLY, people die each year from these things in the wild.

-A large crab, lobster or "spearer" mantis shrimp hiding in the rock

-A large serpent starfish that is hungry. (Would need to be VERY large)

-The fish are being stressed to death by more agressive tank mates.

-Predatory worms.

These are the things I have encountered over the years...

-Alfred
 
well i imagine with a fairly new tank that the chemistry swings are causing much stress on the fish, and perhaps the fish arent well established either, IMO i have never heard my mantis "snap" only actually smashing somethings shell...sometimes snapping sounds are often snails getting rattled on the glass by a powerhead blast, or hermit crabs moving rubble against the glass..i have had a few fish dissapear on me too...not in the mantis tank either...some jump out . some get sucked into powerheads or find their way to the sump and get pureed by the mag 24 like my mantis did...just about everything will eat another dead or dying fish, they get blown around till the get stuck, usually where we cannot see, then nature takes over...i would definitely check on the tank at night, and take a small 1/2 liter water bottlecut the top off at an inch down the side, then invert the top and stick it into the bottom, it should stay, you might need glue....put a piece of raw seafood in there with a few cottonballs(sometimes the shrimp and bristleworms get tangled it them)...submerge it in the tank(remove all air) and nestle it in a corner or cave...please pm me if you catch anything...and if you have an octo, how much do you want for it?
 
<a href=showthread.php?s=&postid=6026989#post6026989 target=_blank>Originally posted</a> by ediaz
The same happened to me more than 15 years ago, i had an small octopus that came with the live rock.

Ed

What type of octopus? do you still have it?
 
While looking in all the little places on my LR in a 3 week old tank I found a cone snail about 1/2 inch long. I got tweezers and grabbed him. Glad he didnt get bigger or that I didnt get stung while working in tank moving LR around! I hope they dont travel in pairs!! Dont know if one this size could hurt a human, but did not want to take a chance.
 
Yes, a tiny cone snail can kill a grown man, some of the most toxic "venom" in the world is produced by them. You are very fortunate.

-Alfred
 
Cone snail!!! Careful with those, some are really dangerous. I've never heard of a serpent star eating fish, but there is one brittle star- I think its a brittle- that specializes in killing fish by making it's body look like a cave. When a fish goes to sleep underneath it, BAM!! There is also a urchin- I think it is called a Pencil Urchin- that is extremely good at eliminating fish. Well, good luck catching and disposing of 'yalls fish and invert nappers!
 
Wow, very lucky you found the cone snail! Would a freshwater dip or hyposalinity get rid of all the unwanted hitchhikers? Also I think some heavy duty gloves might be in order for working in the tank.

Glad my husband didn't see this thread, he doesn't even want me to get a Lionfish. He said he was afraid he'd come home and find me dead in front of the tank.
 
I'm with the fire worm idea, I have had them catch a sick flame angle and consume it in one sitting. Nothing left but the bones. Lil bastards.
 
If you have a power head too low it could be pinning a fish in a tight spot in that mountain of live rock. It only takes a couple of hours in the reef to be eaten up. Check the flow but I would say you have a predator of some kind set a trap to be sure.
 
Watch out for certain mushrooms. We had a one snare a lawnmower blenny bigger than it was---bagged him up like a pig in a sack and expanded while he walloped the daylights out of it. By the time we could get it to cough him up, he was a goner. But it explained the disappearance of a dragonette, a mandarin, and certain other perching or low-riding fishes.
 
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