All my fish died, why?

[shornik]

So it's not like I had a tankful of fish, I had 2 mandarins and 2 pipefish. But they were doing fine, I have plenty of pods in my tank, I've been feeding baby brine shrimp 2x a day. There was no sign of anything being wrong. Then.... I did a water change - I know this must have had something to do with it but I can't figure out why. Before the water change all was good, after the pipefish which were always swimming together began to separate, and started swimming vertically (I thought they were just looking for pods). Then 1 pipefish dies the next morning and the other has been AWOL, the same day a mandarin died and then the next day my last mandarin died as well. With the mandarin I could see it was breathing heavily, but the night before it died I fed it baby brine and saw it was eating.

I tested my water and ammonia is 0, nitrite is 0, nitrate is 0-2 (I can't tell), salinity is 1.0255 which is what it was before the water change. The only parameter that is different from last time I tested was phosphates that went from 0 to .1.

So I mentioned I did a water change, 5 gallons and the tank is a 50 gallon so 10%. During the water change I stirred up the sand to remove diatoms. When you disturb diatoms does that release anything that might have poisoned the fish? I say diatoms because they go away at night with lights out and progressively grow during the day with lights on. And they sure look like diatoms but could be something else.

I do have 3 gorgonians, a xenia, a sympodium and those are doing just fine. I added 2 Acans and mushroom from my other tank and those are doing just fine as well.

So I'm stumped. This tank is being set up for Seahorses and now I'm afraid to put them in the tank. I'm afraid to put anything in the tank to be truthful. So any ideas would be most appreciated.

Thanks as always!

 

[Duke4Life]

My bet is the sand being stirred released some nasty stuff. Sorry to hear this.

 

[LakeCityReefs]

Are you sure the RO water was clean from chlorine? Did you give the salt mix time to mix and relax?
Sounds like a PH or chlorine issue. Could be the sand bed. Any corals dying?

 

[Tahoe61]

If you actively or aggressively stirred up the sand bed you could have disturbed a pocket of hydrogen sulfide, the older the sand bed the more likely an area of the sand bed is anoxic/low oxygen and possibly harboring hydrogen sulfide.

Another scenario is the replacement water was some how compromised.

Double check or calibrate water ever instrument you use to test SG.

What temp is the tank running at?

 

[twilliard]

Tahoe got this one!
That is one of the most commonly overlooked potential tank hazzards.
The release of hydrogen sulfide
Highly toxic (and cyanobacteria loves it)

 

[reefrider777]

water change water might have chloramine in it.

 

[twilliard]

So it's not like I had a tankful of fish, I had 2 mandarins and 2 pipefish. But they were doing fine, I have plenty of pods in my tank, I've been feeding baby brine shrimp 2x a day. There was no sign of anything being wrong. Then.... I did a water change - I know this must have had something to do with it but I can't figure out why. Before the water change all was good, after the pipefish which were always swimming together began to separate, and started swimming vertically (I thought they were just looking for pods). Then 1 pipefish dies the next morning and the other has been AWOL, the same day a mandarin died and then the next day my last mandarin died as well. With the mandarin I could see it was breathing heavily, but the night before it died I fed it baby brine and saw it was eating.

I tested my water and ammonia is 0, nitrite is 0, nitrate is 0-2 (I can't tell), salinity is 1.0255 which is what it was before the water change. The only parameter that is different from last time I tested was phosphates that went from 0 to .1.

So I mentioned I did a water change, 5 gallons and the tank is a 50 gallon so 10%. During the water change I stirred up the sand to remove diatoms. When you disturb diatoms does that release anything that might have poisoned the fish? I say diatoms because they go away at night with lights out and progressively grow during the day with lights on. And they sure look like diatoms but could be something else.

I do have 3 gorgonians, a xenia, a sympodium and those are doing just fine. I added 2 Acans and mushroom from my other tank and those are doing just fine as well.

So I'm stumped. This tank is being set up for Seahorses and now I'm afraid to put them in the tank. I'm afraid to put anything in the tank to be truthful. So any ideas would be most appreciated.

Thanks as always!

Oops missed one sorry!
No those are not diatoms you are stirring up. Diatoms do not act that way, not like an active bacteria does.
Something like spirulina does though.
https://www.reef2reef.com/threads/positive-identification-of-cyanobacteria.253287/

 

[Wiz]

"Grows during the day and dies at night" huge red flag for me. Possible dinos. Its the only thing I know that grows in one day and dies at night. Might wanna look into that. Very sorry for your loss. :-(

 

[shornik]

Are you sure the RO water was clean from chlorine? Did you give the salt mix time to mix and relax?
Sounds like a PH or chlorine issue. Could be the sand bed. Any corals dying?

I have a RO/DI and always use it. I also have another tank and did a water change the day before the tank that the fish died in, and no problem with anything in that tank so I don't think it's chlorine. I tested the PH (forgot to mention that in the original post) and it hasn't changed since the water change either.

 

[shornik]

In addition to not mentioning I use RO/DI I also neglected to mention the tank is 3 month old. Can there still be such a build up of hydrogen sulfide? But certainly I was stirring up the sand bed more then I normally would to get rid of whatever is growing on it. Speaking of that if I understand correctly @twilliard is suggesting its not diatoms but @Wiz thinks they might be? The color of it is brown on the sand bed not red or green. I'll do the test to see if I see any water changes and go from there. Thanks everyone for your input.

 

[Wiz]

I don't know, but from your description it does not sound like cyano or diatoms to me. It sounds like dinoflagellates. That is just a guess though I definitely could be wrong. And if your tank is only 3 months old I seriously doubt you had a good enough pod population for two pipefish and two Mandarin. I am not judging nor am I saying that definitely. Just a guess. I would imagine starvation was not the problem though being that they all died close together. If it is dinos and they ate it that could definitely be a Cause.

 

[Wiz]

Doess the brown stuff that grows have little air bubbles attached to it? Do you have any pictures

 

[shornik]

Doess the brown stuff that grows have little air bubbles attached to it? Do you have any pictures

I've never noticed air bubbles but I haven't been looking for them either. Lights just came on so I'll take a picture and then a few more as whatever it is grows and then post it here so you can see what I've been talking about.

 

[twilliard]

Pictures do help but I am not sure the dinoflagellate population would be high enough to kill all the fish so quickly.
Velvet?
@Humblefish @melypr1985 is it plausible?

 

[Wiz]

My guess is solely based on the rate of growth at this time. Could definitely be wrong. I am not familiar with velvet.The only thing I've come across that grows in hours is dinoflagellates.Some of these other guys are probably more experienced than I.And as for whether or not it killed your fish I don't know. I also have trouble believing it would have killed all four that quick

 

[don_chuwish]

Dinoflagellates do usually have air bubbles. Not trapped underneath like a cyano carpet, but more like 'float bulbs' in the individual slimy strings. Google some photos and you'll get the idea. Haven't heard of them killing fish though. Also don't think stirring the sand would have done it on a young tank. Quite a mystery this one!

 

[Humblefish]

It's my understanding that exactly how dinos kills snails (and sometimes other livestock) is still somewhat of a mystery. Is it because the animal eats the dinos or is it due to toxins being released into the water from the dinos? If the latter, then stirring up the sand bed (and dinos) could have done it. Especially if this was a small tank.

Hitting a sulfide pocket or a toxin getting into the new water are other definite possibilities.

 

[fab]

Very, very sorry for this confounding tank crisis having happened to you.

How deep, thick, is the sand bed? And if it is not uniformly deep how deep is the deepest part of it?

@Randy Holmes-Farley, is there any way to test for hydrogen sulfide - even now, post facto, perhaps for newly building gas pockets in case there are any? What might cause a hydrogen sulfide buildup if the sand bed is, say, under 3" deep?

Do the behavioral symptoms that the fish presented point to or away from any possible causes?

This is quite scary. Sudden death for no known or even apparent reason. Thank goodness the OP did not have thousands of dollars of livestock at risk when this wipeout occurred.

I hope for all of our sakes that some kind of post mortem analysis can pin down what caused this sudden, simultaneous die-off.

 

[shornik]

Here are 3 pics each taken about 2-3 hours apart. It's hard to tell that the whatever it is, is growing but I'll get another pic tonight when most of it will have gone away. It might go without saying but its this stuff that I stirred up with the sand when I did my water change. I still don't see bubbles. If you want anything else closer up pics, etc. let me know...

Actually in this last picture it looks like its getting a little less covered to me.

 

[Wiz]

I agree the last picture does look a little better. Are those daytime pics they are not very bright. If you could get more lit pics so we can see the algae or whatever clear that would be great. The growth rate definitely worries me. Does it grow on rocks and coral too or just the sand?