Help!

[Pablos]

I got up this morning to go to work and put the light on in my marine tank. All my fish were fine swimming around. I've just got home and there all dead. Starfish is fine atm, crabs fine, shrimps fine. But the rest dead. Softy's look ok. What's going on?? Im just bout to do a ammonium test and a nitrite test. What do i do?? The only new thing we have done is brought more salt ro water and done a 10% water change on friday. Please Help!! What could have happened???

 

[Colin_T]

Possibly whitespot, bacterial infection or low oxygen levels. Do any of the fish look red around the body or any unusual patching?

It's unlikely to be water quality if you have cleaner shrimp in the tank and they are fine. Remove the bodies and leave the tank for an hour, then check it. If there have been lots of dead fish in the tank you will probably have an ammonia reading from all the bodies. Check the water again in 24 hours to see if there are still high ammonia readings.
If you have a protein skimmer it should be going nuts so check that as well.
Check the temperature to make sure you haven't cooked the fish, and make sure the filters are running properly.

 

[Pablos]

Possibly whitespot, bacterial infection or low oxygen levels. Do any of the fish look red around the body or any unusual patching?

It's unlikely to be water quality if you have cleaner shrimp in the tank and they are fine. Remove the bodies and leave the tank for an hour, then check it. If there have been lots of dead fish in the tank you will probably have an ammonia reading from all the bodies. Check the water again in 24 hours to see if there are still high ammonia readings.
If you have a protein skimmer it should be going nuts so check that as well.
Check the temperature to make sure you haven't cooked the fish, and make sure the filters are running properly.

Done Water checks
Nitrit is fine
Ammonium is a little high but not bad for something like this to have happened.
Skimmer seams to be working fine as far as i can see. filter fine, Was hot dwn here today but not that hot in the house. ive had the fans going.
other tanks seem fine. Unless it was that. Its had to know as no one was in the house. Everything seems fine.

 

[Musho3210]

unfortunately, we cant really tell if ammonia was the culprit, if you check it now, it will probably be high since of all the die off, but we dont know if it was previously high, or that something else caused the deaths which then caused the ammonia.

Anything above 0 ammonia on hobby test kits has the power to do something like this.

 

[Colin_T]

Unfortunately things like this sometimes happen and you never find out why. It happened recently in my LFS, they lost most of the fish in a display tank. They were fine one day but dead the following morning.
There were a couple of theories including a few fish had died and produced ammonia. The CO2 unit malfunctioned and the PH controller raised the PH to compensate for the CO2 dropping the PH. Then the ammonia (produced by the dead fish) became toxic because of the higher Alkaline PH. The combination of excess CO2 at night with minimal surface turbulence and high ammonia levels in alkaline water put too much stress on the fish and wiped them out.
A similar thing can happen in a marine tank due to the alkaline PH of seawater (approx 8.4). It only takes a very small amount of ammonia to cause serious problems when the PH is that high. You might have lost a fish overnight and the ammonia levels weren't too bad. But during the day as the body started to decompose, the ammonia levels went up and reacted in the alkaline water, and wiped the rest of the fish out. But because the shrimp are ok it probably wasn't that.

You could take a couple of the bodies to a fish vet and have them autopsied. Then at least you would know if it was a disease. If the fish are clean and free of disease then it has to be the water.

Was the new water mixed for any length of time before you used it?

 

[SkiFletch]

what fish did you have pablos? Sounds more like Oxygen deprivation coupled with just a little ammonia...

 

[tropicalwaters]

did you spray anything? cleaning etc? or paint possibily?