Fish disappearing

[Aqualoon]

Tank is a 29 Gallon with about 40-55lb of live rock.

I got the tank back in June fully setup and all livestock included. The live stock that came with it was the following: 6 line wrasse, yellow tail damsel, cardinal fish, clownfish, bicolor dottyback, skunk shrimp and 10ish blue legged crabs.

All the livestock was thriving, eating well, water changes were going well - basically everything was doing great. The SW thing wasn't as hard as I made it up to be in my head (granted I have not done any corals yet).

Mid August I decided to change the substrate to sand (CaribSea Aragamax Sand). Anyways, I first noticed my dottyback was missing but didn't think anything of it since it liked to hide in the rocks, then the yellow tail, then the wrasse and then the clown. I can't find their bodies when searching for them and I really don't know what happened.

All I have left are the crabs, skunk shrimp and the cardinal fish - they have been by themselves for the past week and a half to two weeks now. The survivors are doing well and acting normal (but so were the others before they went missing).

Any thoughts on what's going on here? If there was an unknown predator in the tank I wouldn't think that these fish would have lasted from June to August. Which means that maybe it hitched a ride in the sand? If that's the case then what could be that small to go un-noticed in sand?

I don't want to restock until I find out what's going on.

[merek123]

maybe a mantis shrimp? people say you never see them. Have you ever heard a clicking noise?

[Aqualoon]

I haven't heard anything along those lines.

If it is a Mantis Shrimp wouldn't it have started to get to work on the livestock in June and July?

[Ohiomom]

Any chance of an unknown brittle star? Some can be predatory..

[Aqualoon]

I'm not sure...I mean I took out every piece of live rock (keeping it in water of course) and changed out the crushed coral.

I have personally taken down this entire tank twice now in 3 months and put it back up and haven't seen anything out of the ordinary (I helped the original owner take it down so I knew how to do it when I purchased it).

[El Diablo]

Fish can die in a established system and can just decompose in around three days. So I would check your params and I can guarantee that is where your fish are going.

[Aqualoon]

Parameters were the first thing I checked. I have been checking them weekly since I got the tank in June and have been doing my 10% weekly waterchanges without fail.

Everything is in order - which is why I am really confused.

[Aqualoon]

You know, I didn't even think about this...

The VERY night I switched from crushed coral to sand there was a tornado in my town and I was without power for 13+ hours because of downed power lines and trees on said power lines.

Could that be a large contributing factor?

[Ohiomom]

Very much so..the change in temperature alone would be an issue along with no power no filtration, no oxegyn exchange..that is your answer..will need probably to recycle the tank..sorry for your losses.

[Mayesj101]

No, if it was a temperature shock that did them in, then A) they'd all have died at once, B) you'd have lost that skunk shrimp far before you lost a yellowtail damsel (skunk shrimps are extremely intolerant of wide H2O condition swings, while damsels are probably the most hardy fish in our hobby), and C) there is no way that 10 hermits and a skunk could dispose of 4 decent-sized fish before you could see it, and without any major change in water parameter.

With all of the above in mind, I'd say that you've got a fairly small mantis shrimp. Mantis are notorious for hitchiking within miniscule holes in live rock. Also, they're almost entirely nocturnal-they spend the days asleep, and the nights hunting sleeping fish and expanding their burrow in the rock.

A good way to check on a mantis is to stay up late at night and listen to very light taps coming from the rockwork. It might take a few nights, but be patient. Once you've ascertained that you've got a mantis, you've got to be really careful-mantis are also known as "thumbsplitters", as one species in particular (the California mantis, if I remember correctly) can strike with the approximate force of a .22 caliber bullet. Use tongs or something to move a single rock into a 5-gallon bucket, then add something like a feeder shrimp (something that will survive in SW); and wait a night or two. If the shrimp is still there, then move on to the next rock. If it's not, you've found your mantis. There're several mantis traps you can find online. Then, you can either dispose of him, or get another tank set up and enjoy them for the fascinating creatures they are. Just make sure if you set up another tank that it's an acrylic, as most are well capable of cracking glass if they set their minds to it.

[Aqualoon]

I'll stay up late over the weekend and see if I can't hear anything.

However wouldn't the shrimp have eaten any of the fish in June, July and half of August?

I bought the tank in June - tank came with crushed coral. I left it this way until Mid August when I changed the substrate to sand (later that day a tornado hit my town and I was without power for 13+ hours).

Before that night all the livestock was thriving for 2.5 months together and everything was going well.

I do agree with the temperature bit though, I would have thought the skunk shrimp would be the most sensitive. But with that same thought process wouldn't a freshly molted skunk shrimp be the easier target for a mantis shrimp?

[Ohiomom]

Didn't say it was the cause..merely part of the issue..:)

[Aqualoon]

Stayed up Friday and Saturday late then last night until 11 or so and couldn't hear anything.

Since I hadn't had any fish deaths in two months and then had the majority of my stock disappear within a week or two time period I'm not 100% sold on the Mantis Shrimp idea. If there is a predator in the tank then it would have had to hitch a ride in the sand I bought. Is there something small enough that could hitch a ride in the sand?

And the cardinal fish and skunk shrimp are still around and doing well.

[stevek480]

Is it possible changing out the old sand may have stirred up toxins that were trapped in it?

[mal1099]

Maybe a nasty crab then also. I personally would take the rock out and hit it with carbonated water. and you will find your little nasty

[Aqualoon]

<a href=showthread.php?s=&postid=15628575#post15628575 target=_blank>Originally posted</a> by mal1099
Maybe a nasty crab then also. I personally would take the rock out and hit it with carbonated water. and you will find your little nasty

Would that damage the live rock a great deal as well? And I would imagine that would kill the mushrooms and small feather dusters I have going as well?

[judgedread]

<a href=showthread.php?s=&postid=15604722#post15604722 target=_blank>Originally posted</a> by Aqualoon
Tank is a 29 Gallon with about 40-55lb of live rock.

I got the tank back in June fully setup and all livestock included. The live stock that came with it was the following: 6 line wrasse, yellow tail damsel, cardinal fish, clownfish, bicolor dottyback, skunk shrimp and 10ish blue legged crabs.

All the livestock was thriving, eating well, water changes were going well - basically everything was doing great. The SW thing wasn't as hard as I made it up to be in my head (granted I have not done any corals yet).

Mid August I decided to change the substrate to sand (CaribSea Aragamax Sand). Anyways, I first noticed my dottyback was missing but didn't think anything of it since it liked to hide in the rocks, then the yellow tail, then the wrasse and then the clown. I can't find their bodies when searching for them and I really don't know what happened.

All I have left are the crabs, skunk shrimp and the cardinal fish - they have been by themselves for the past week and a half to two weeks now. The survivors are doing well and acting normal (but so were the others before they went missing).

Any thoughts on what's going on here? If there was an unknown predator in the tank I wouldn't think that these fish would have lasted from June to August. Which means that maybe it hitched a ride in the sand? If that's the case then what could be that small to go un-noticed in sand?

I don't want to restock until I find out what's going on.

hmmm black hole syndrome huh?
have a look behind yr tank you might find some crispy fish fritters there or if you got a cat then he prolly ate em before they got that far lol...

[Aqualoon]

I have two cats - one that isn't interested in my tanks and my 12 week kitten who decided to help me drain some tanks yesterday by climbing up into them :mixed:

And the Cardinal fish and Skunk Shrimp are still in there - doing fine, swimming, eating, etc.

[svynx]

<a href=showthread.php?s=&postid=15624782#post15624782 target=_blank>Originally posted</a> by stevek480
Is it possible changing out the old sand may have stirred up toxins that were trapped in it?

I'd agree with this, and add in the fact that you took out a big part of the filtration that the tank had. You went from an established sand to a brand new one, without any of the beneficial bacteria. You could have had a mini cycle and not even known it. That plus the power going out could have been enough.

[Sugar Magnolia]

It's possible that the damsel, the dottyback or sixline killed the others and each other. The damsel is an aggresive fish, especially a yellow tail damsel. If it went after the sixline, the sixline would have put up a fight. Same goes for the dottyback. You had all those aggressive fish together in a relatively small space. The territorial fighting was just waiting to happen as the fish established themselves. Just something to think about...and for future stocking decisions.

[Luis138]

In what amount of time did they disappeared? Did they disappeared one per night or how?

Luis

[VacavilleFC3S]

i'm going to assume you cause your tank to cycle when you removed switched substrates and 1 by 1 the fish died and were eaten by your clean up crew.

[Jaycen B.]

Is the tank topless? Cats like fish! Mine made my firefish jump out and than ate him. BAD CAT!!

[sks4613]

hmm possibilities....
Cats.... very good one. You cant watch them 24/7
Power outage could be but you could assume it would affect all.
fighting is a very real option don't think you could have missed it though you would have known.
Toxins in the sand again very real but it would not target specific fish. they all would have been affected.
Crabs possibly..... not likely.
Mantis shrimp is a very real one. Would move quickly and unless you just happened to be there to see it. You will only hear the clicking sound when it is redoing its home. If it found a suitable place it may not enlarge it for a while till it grows.
I would remove the rocks hit them with carbonated water if there is a mantis he will come shooting out. Take the opportunity to clean the tank a little and replace rocks. This would eliminate in my mind the nastiest of the possibilities mentioned. Sounds like these were the smallest of the fish in the tank... he could just be growing and waiting to take down the rest.
Brittle star not likely I don't think you could miss see a leg or something.
Best of luck. JMO