The case of the mysteriously disappearing fish (mantis shrimp?)

[Zorya]

Hi, I'm posting for a friend.  He's got a 40 gallon breeder tank and has various SPS in it and it's doing really well.  The problem is that he has now lost 3 pairs of clowns, 2 firefish, and 3 wrasses since the beginning of the year.  Nothing else is dying (lookin at you hermit crabs) and the corals aren't bleaching, but growing rather nicely.

 

The mysterious part is that when a fish goes missing it is always:

1. very early in the morning - he goes to sleep around 2am or 3am as he works on his tank late at night some nights

2. no body floating around - you would think that if a fish died from disease, stress, water params, etc that it would be floating around or stuck in a rock or something, but there's no sign of it anywhere, not even bones

 

I have concluded that there must be a mantis shrimp that has hitchhiked in from who knows where and it is eating the fish.  Thoughts?

 

He is going to set up a trap tonight, but I don't know what kind of trap.  We have looked everywhere for the mantis shrimp or other offender that looks out of place and cannot find anything (including moving all the rocks).  What types of traps work for mantis shrimp (besides spearing it because we can't find exactly where it is)?

add a goby to that, forgot about him 😢 he was the first disappearance, but we figured he was shy and scared and died from not eating

[Clown79]

If he had a mantis he would hear it. They make a very loud noise that you cannot not hear.

 

It can sound like the tank is cracking.

 

There are other things though that can kill a fish. Certain hitch hiker crabs or even a bobbit worm.

 

The other issue with fish disappearing, they can die in rocks and never be located.

 

Within hrs a clean up crew can demolish a dead fish between snails, hermits, pods, bristle worms there can be no evidence of a fish in no time. 

 

If your friend finds no evidence of a killer hitchhiker, there is a possibility of disease especially if there wasn't 8 weeks fallow between fish additions.

[Zorya]

2 hours ago, Clown79 said:

If he had a mantis he would hear it. They make a very loud noise that you cannot not hear.

 

It can sound like the tank is cracking.

 

There are other things though that can kill a fish. Certain hitch hiker crabs or even a bobbit worm.

 

The other issue with fish disappearing, they can die in rocks and never be located. 

 

Within hrs a clean up crew can demolish a dead fish between snails, hermits, pods, bristle worms there can be no evidence of a fish in no time. 

 

If your friend finds no evidence of a killer hitchhiker, there is a possibility of disease especially if there wasn't 8 weeks fallow between fish additions.

He has pulled the rocks out several times to try and locate any bodies and couldn't find any.  That's why I thought maybe it was something that was on the rocks or in the sand.  I also suggested bobbit worm, but I'm not sure how much substrate they need because he only has about 1" of sand down.

[Clown79]

5 hours ago, Zorya said:

He has pulled the rocks out several times to try and locate any bodies and couldn't find any.  That's why I thought maybe it was something that was on the rocks or in the sand.  I also suggested bobbit worm, but I'm not sure how much substrate they need because he only has about 1" of sand down.

You normally don't find bodies.

 

The clean up crew will clean up a fish within hrs.

[Snow_Phoenix]

I had fish go missing/dead too in my current tank. I kept thinking either the tank was jinxed, a mysterious underwater portal had opened up under the rocks or the fish was simply sick when they arrived from the store. Turns out my Daum's reef lobster had been hunting down all my fish one by one, starting with my YCG. He was fed every day and yet he took down a 3.5" healthy flasher wrasse. I only found out because I took a pic of my wrasse sleeping behind my skimmer, went down for breakfast, found the fish 'missing' when I returned and then noticed half of its body jutting out from under the rocks. The fish was wriggling when I pulled it out...and the lobster was attached to its face and trying to eat it. 

 

It might not necessarily be a hitchiker offing your fish - ask your friend if he has anything else other than hermits for inverts in there (which he willingly put in). If it's a reef lobster, get it out immediately. If it does turn out to be a hitchiker issue, then it *might be a eunicid or bobbit worm. As Clown has mentioned, if it was a mantis, you would have heard it by now. Same goes for a pistol shrimp. 

P.S. If by some chance it is indeed a mantis, don't kill it. There are people who set up species tanks for them, and wouldn't mind keeping one. So give it away to someone who can and is willing to give it a home. Mantises get a bad rep. in the hobby, but they're actually wonderful and amazing critters. 

[Clown79]

2 hours ago, Snow_Phoenix said:

I had fish go missing/dead too in my current tank. I kept thinking either the tank was jinxed, a mysterious underwater portal had opened up under the rocks or the fish was simply sick when they arrived from the store. Turns out my Daum's reef lobster had been hunting down all my fish one by one, starting with my YCG. He was fed every day and yet he took down a 3.5" healthy flasher wrasse. I only found out because I took a pic of my wrasse sleeping behind my skimmer, went down for breakfast, found the fish 'missing' when I returned and then noticed half of its body jutting out from under the rocks. The fish was wriggling when I pulled it out...and the lobster was attached to its face and trying to eat it. 

 

It might not necessarily be a hitchiker offing your fish - ask your friend if he has anything else other than hermits for inverts in there (which he willingly put in). If it's a reef lobster, get it out immediately. If it does turn out to be a hitchiker issue, then it *might be a eunicid or bobbit worm. As Clown has mentioned, if it was a mantis, you would have heard it by now. Same goes for a pistol shrimp. 

P.S. If by some chance it is indeed a mantis, don't kill it. There are people who set up species tanks for them, and wouldn't mind keeping one. So give it away to someone who can and is willing to give it a home. Mantises get a bad rep. in the hobby, but they're actually wonderful and amazing critters. 

I had a hitchhiker pistol once. 

 

The first time I heard the noise I thought my tank was cracking. 

 

Every night he could be heard.

 

 

[Zorya]

Thanks for the responses!  He isn’t planning on killing the mantis shrimp if he finds out it is one of those, but he hasn’t heard any clicking. The inverts he doesn’t want in the main display go into another tank which is his sump, but it’s not yet connected to the main display (don’t ask me why). I’ll let him know what you guys have said and see if it helps. 

[luckie1966]

15 hours ago, Zorya said:

Hi, I'm posting for a friend.  He's got a 40 gallon breeder tank and has various SPS in it and it's doing really well.  The problem is that he has now lost 3 pairs of clowns, 2 firefish, and 3 wrasses since the beginning of the year.  Nothing else is dying (lookin at you hermit crabs) and the corals aren't bleaching, but growing rather nicely.

 

The mysterious part is that when a fish goes missing it is always:

1. very early in the morning - he goes to sleep around 2am or 3am as he works on his tank late at night some nights

2. no body floating around - you would think that if a fish died from disease, stress, water params, etc that it would be floating around or stuck in a rock or something, but there's no sign of it anywhere, not even bones

 

I have concluded that there must be a mantis shrimp that has hitchhiked in from who knows where and it is eating the fish.  Thoughts?

 

He is going to set up a trap tonight, but I don't know what kind of trap.  We have looked everywhere for the mantis shrimp or other offender that looks out of place and cannot find anything (including moving all the rocks).  What types of traps work for mantis shrimp (besides spearing it because we can't find exactly where it is)?

add a goby to that, forgot about him 😢 he was the first disappearance, but we figured he was shy and scared and died from not eating

I got a better question for you. Does your friend have a very tight fitting cover to prevent escapes because if not I'll guarantee the wrasses went carpet surfing?

[Zorya]

3 hours ago, luckie1966 said:

I got a better question for you. Does your friend have a very tight fitting cover to prevent escapes because if not I'll guarantee the wrasses went carpet surfing?

He does. Thanks for reminding me - I didn’t put that information at the beginning!

[A Little Blue]

Certain worms or serpent stars can do that kind of damage. I know it sounds silly, but I have seen it before. 

[mndfreeze]

It's definitely not a mantis.  I'm a mantis lover and former owner.  His CUC, not fish, would be the ones getting destroyed by a smasher mantis and a spearer would be a giant pile of obvious with hits head sticking out of a burrow in the sand.

 

My money is on some other inhabitant, or something like a worm.  There are a lot of sneaky predator worms and snails that can take out a sleeping fish.

 

[Zorya]

On 11/8/2018 at 2:49 AM, mndfreeze said:

It's definitely not a mantis.  I'm a mantis lover and former owner.  His CUC, not fish, would be the ones getting destroyed by a smasher mantis and a spearer would be a giant pile of obvious with hits head sticking out of a burrow in the sand.

 

My money is on some other inhabitant, or something like a worm.  There are a lot of sneaky predator worms and snails that can take out a sleeping fish.

 

We didn’t ever figure out what it was 😞 

 

My friend didn’t end up getting any more clowns, but has gotten a couple wrasse and cardinals and they are still doing great.

[PapoReef]

Nice update! very strange though. So he never had any issues again? nor with the cuc?

[Zorya]

Nope, no issues. His tank is actually undergoing a little bit of a meltdown - his sps are doing poorly except the acros and all his lps are fine, but no other problems with fish for some reason. 

[StealthPrix]

I second the possibility of serpent stars. I had one that got one of my clowns at night. I only knew it was the star because I caught him actively reaching for my other clown.