Unusual fish dying problem - please help!

C

c_paul

New member
Hi All,

I have an interesting challenge and am at a loss and the LFS also drew a blank.

I have a 100g SPS tank that was setup in 2011. Until this problem I have only lost a few fish in total. For the last 18 months I have been losing one fish at a time every 2 - 3 weeks.

No new livestock has been added to the tank since 2013 when I bought some new coral. The missing fish either disappear or are found without any marks, injury or visible cause.

There is only one fish (a Bangai Cardinal) that has survived. All my clowns, tangs etc. have all perished.

What on earth can be causing the problem?

My thoughts:
Predator
The regular stream of victims would indicate a predator but nothing (no new rock etc.) has been added since the tank was first established. Furthermore, the reason I had to add new coral in 2013 was because of an ATO fault dropped the salinity to 1.007 and killed all the inverts and corals. All the fish survived would you believe. I have never seen (or heard) any evidence or indication of a pistol shrimp etc.

Water quality
We moved house 6 months ago (the problem started before then) but we have been busy so water changes have not been as regular as they should be.

I don't see why this would affect only one fish at a time though?

All the inverts are fine.

The corals (almost all SPS with a wide range of montys, some easy and some really tricky Acroporas) are doing brilliantly! I have some amazing pinks, blues and greens.

Electrical charge
I can't say for sure as I have not got exact records on when each fish died but I have upgraded the skimmer and power heads in the last 2 years.

I now run a pair of RW15s. I used to run a couple of single speed Koralias.

Could these be shocking the fish somehow?

Again, why one at a time.

Any ideas?

I don't know what to try next.

Thanks,

Chris
 
I've had electrical current in my tank before. It's no fun and it can kill the fish. I'd try to test for that
 
killagoby said:
I've had electrical current in my tank before. It's no fun and it can kill the fish. I'd try to test for that
Click to expand...

I found out I had a stray current in my tank when I felt a light tingle when my hand was placed in the tank. The fish were acting a bit odd by swimming erratically and scratching on rocks. All was good when I removed the pump.
 
Fish dying/disappearing one by one over time would make me suspect a predator was involved. Just because you don't see one, doesn't mean it isn't there. You could have a brittle star or (God forbid) a bobbit worm lurking in your tank. Crabs can also take fish.

Stray voltage would affect all the inhabitants simultaneously.
 
Also to keep in mind, a predator can be introduced as a tiny juvenile or even as an egg hitching a ride with a coral or other invert, especially if those inverts can't be put into a coral dip.

Large brittle stars are quite capable of catching fish by quite literally setting up traps. And these guys can have nasty teeth as well. I would never again put one of those knowingly into my tank, let alone pay money for it.
The tiny ones are good though.
 
Thanks for the replies.

I am happy to follow the predator line of thought as it is the only thing I can think of that would only affect one fish at a time.

The question is how to find it / what is it?

All sizes of fish have been affected from small damsels to a Regal Tang that was maybe 10 inches.

All the live rock and sand was exposed to a salinity of 1.007 for about a week so anything will need to have survived that or come as a very small hitch hiker. I dip / qt everything!

I have also moved house and didn't find anything at that time. I removed all the crabs I found bar a couple of tiny red legged hermits.

Only the Bangai Cardinal has survived. Could he be our assasin? He has always been aggressive to newcomers. But could he kill a 10" tang?

Is it worth setting some traps?

Chris
 
If the Banggai Cardinal is the culprit, you should take him on the road and charge admission. :D

As far as catching the predator, you'll need to identify it first. Using a red flashlight at night might reveal the perpetrator.
 
I think some crab and worm traps are a good idea.

While Banggais can get quite aggressive, I doubt they are equipped to do too much harm. A tang would definitely have the better weapons in a fight.
 
Deinonych said:
Fish dying/disappearing one by one over time would make me suspect a predator was involved. Just because you don't see one, doesn't mean it isn't there. You could have a brittle star or (God forbid) a bobbit worm lurking in your tank. Crabs can also take fish.

Stray voltage would affect all the inhabitants simultaneously.
Click to expand...

While I agree that fish disappearing one at a time sounds like a predator, the ones that the OP found dead looked physically unharmed. Wouldn't a predator leave evidence of predation on the body of the fish?
 
krullshards said:
While I agree that fish disappearing one at a time sounds like a predator, the ones that the OP found dead looked physically unharmed. Wouldn't a predator leave evidence of predation on the body of the fish?
Click to expand...

Good point, one would think so. I'm at a loss as to the cause.
 
Exactly!

That's why i have run out of ideas.

I need a process of elimination but have run out of fish and am unhappy about buying more knowing they will die.

What preditor doesn't leave a mark? Stun /sting? Bearing in mind the only corpses I have found are for the large fish. The small ones just disappeared.

Sherlock Holmes?
 
I once had a Gorilla Crab hitchhike on some rock into my tank. It took months to figure out and I had to tear down my rock to get him
 
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