Dead Clown and Hermit Crab

[Malibu41]

Just got back from Orlando for the day and found my bigger Clown (about 1 1/2 years old) and one of the Hermit crabs dead in the back corner of my tank. The crab appeared to be torn in half and maybe a mark on the side of the clown. Would they have killed each other?Maybe I have a visitor in the live rock I have not seen yet that did it? I caught a glimps of a creature the other day that looked like a short fat centipede but that didnt seem big enough, maybe 1/4 inch long. There also appear to be hundreds of small white bugs on the glass and rocks that I didnt see before, maybe a hatch? They are as small as a tiny grain of sand and are crawling all over the place. I took some photos but they dont show well. I added a Small Emerald crab and 5 more small hermits yesterday but I cant imagine they came in with them. Just kinda wierd the bugs showed up at the same time as the deaths.

[Malibu41]

Looks like from what I have been reading the bugs are not a bad thing but a form of zooplankton. Back to my first thought maybe the fish and hermit crab killed each other...... All levels look good, PH a little high at 8.4 but everything else is @ 0. The clown seemed healthy and the other clown is fine.

[CarmieJo]

The bugs look like copepods to me and should not cause any problems.Tthe centipede sounds like a bristleworm and most are harmless detrivores. A hermit ripped in half sounds like a predator but I think it would have to be something like a mantis.

[Rostr02]

Sorry to hear about your losses. How long where you gone for?

[Malibu41]

Its crazy! Normally there is someone home being as my kids are home schooled. Today we went to Orlando around 11am and back by 9ish so not that long really.

[CarmieJo]

You didn't have any evidence of a power outage did you?

[Malibu41]

No sign of power outage. I did spot some type of creature in the rocks where the clown died. I wasn't able to get a good look, though.

[Rostr02]

If your clown was alive before you left then all of the sudden in half when you came back a few hours later, I am going to have to agree with carmie that you may have a mantis floating around in there. might want to try a bottle trap.

Bob

[Malibu41]

Well the other clown is dead also. It was hanging around in the rocks where I found the other one and the half a crab. As many times as I chased it out the little dude kept going right back, then it was gone. I found it under the rocks in the same area. I made two traps out of plastic condiment cups and placed them in the tank. I cut a cross shape opening in each and placed a little raw shrimp in each. I am pretty sure what I saw was a Mantis in a hole in the rocks. I guess for now I will leave the tank empty of fish and hope I can figure this out. At this point I have lost 1 Hermit crab, a snail I found that I thought the crabs got and both the Clowns. Thanks for the help.

[CarmieJo]

If the condiment cups don't work try taking a plastic 16 or 20 oz pop bottle, cut the top off a little way below the shoulders, reverse it so the mouth of the bottle is pointing towards the bottom (the 2 cut edges will line up together), and glue the 2 halves together. Pop the bait in through the mouth and place it on the bottom of the tank. A mantis will be able to crawl in but should not be able to crawl back out.

[PhotoJohn]

if you have a mantis in your rocks it should be pretty obvious as they like to wack things making a loud poping sound. If you have a spearer it would be in the sand

[Malibu41]

What is a spearer? Going to google, thanks.

[CarmieJo]

Some mantis club their prey and some spear their prey. Whether you have a mantis or not this video is really cool. Sheila Patek clocks the fastest animals | Video on TED.com

[Malibu41]

I saw the creature again as well as some others I didn't know were in there. I have not heard any tapping so I am thinking I have the spearing type. I saw it a little while ago and tried to suck it up with a baster but know luck, it was in a hole in the rock. I will keep you posted but if this goes on too long I will pull that rock and try to get it by isolating it in a bucket of salt water. I saw another thread that said if I dip the rock in super salty water. They said it stuns everything in the rock and they will fall out. Have you heard of that? Its only one rock I guess I could just pull it and be done. Also lost a Blue leg crab today, ripped in half just like last time. Thanks Carmie

[CarmieJo]

Divers call mantis "thumb splitters" so do be careful in case that is what it is. Most would be too big to suck up in a turkey baster.

I have heard to dip it in fresh water. Just be aware that this causes osmotic shock and will kill good and bad life on the rock. Either way you are creating osmotic shock.

[Malibu41]

If I dont catch it by this weekend I may pull the rock and place it in a bucket of normal salt water, maybe if I take it away from the food supply i will catch it in the trap.

[Malibu41]

Still no luck catching anything in my trap. I may try and pull that rock and put it in a bucket of saltwater for a couple days, then try the bottle trap Carmie mentioned. Is there any chance my new Emerald Crab is the killer? I had read they were peaceful.

[CarmieJo]

I think it is unlikely that an emerald crab is the culprit.

[Malibu41]

Thats good to hear! Its currently my favorite.

[Rostr02]

Any luck yet finding the culprit?

Bob

[Malibu41]

I think I have found where it lives but no luck catching it. I went to my LFS today and he said freshwater dip will bring it right out. He also said if its a Mantis he will buy it. The good thing is I have not had any more deaths in about 2 days. I plan on doing the freshwater dip in the morning.

[V]

what have you introduced recently for this to be a new occurrence bud? Or on the flip side, have you cut down the feeding routine as of late

If you suspect a mantis, you can bind a guitar pick to a tooth pick & place it near a suspected entrance. That will soon tell you.
I wouldn't say its bristle or fireworms, they scavenge and are akin to opportunistic feeds rather than predators.

Fresh water dip is the last resort, however given the losses, you may be there already.

[Malibu41]

The only thing I added was a Emerald Crab last Sunday. It seems to mind its own business though, it just hangs out in the rocks and eats algea. I tried to trap whatever is killing with shrimp in a home made trap with no luck. I have seen what I think is a fireworm or two (centipede like body with one end red the other end dark red brownish). I did see what I thought is a small Mantis in a hole that runs down through the rock and comes out to a dugout area of sand under the rock. Thats where I found the first clown as well as the torn up Hermit crab. The next day the other clown would not leave that area and kept sticking his nose in the hole. He was there then he was gone! I pulled the rock up and he was dead under in, it couldnt have been 10 min since I had seen it swimming around. In hindsight I should have pulled out him when I couldn't keep him away from that corner. I could have put it in the little 2.5 gal until I got this figured out. The Emerald crab spends alot of time in that area but has not been bothered yet. I may through him in the little tank until I get this sorted out. On the plus side my algae is just about under control. I have stopped feeding fish food into the tank after the second clown died, there's no fish. I wasn't sure if I should still put a little in for the Nasarius snail but the guy at the LFS said they don't need it. Any advice?

[CarmieJo]

You will need to feed the Nassarius. They are carnivores and so it is not like they will eat algae that might just be present in the tank.

[Malibu41]

So I am going to pull the Emerald crab out if I can catch him in the open. I am still getting Hermit crabs torn apart about once every two weeks. The killings started about a week after I added it and I saw him attack a Hermit crab the other day. Any of the corpses have been close to where his "home" is and after two months still no signs of a Mantis. I don't want to add anymore livestock until I get it out.