Half my fish died last night

smokinprice

New member
To All,

I need some help. I woke up this morning to find half of my fish dead. Last night I lost my Yellow Tang, Pajama Cardinal and Falco Hawk Fish. The tang and cardinal I have had for over two years. I check everything that I could think of and the results were as follows:
Salinity 10.22
Ammonia 0
Nitrate 25 ppm
Nitrite 0.3 mg/l (less than this)
PH 7.8

I still have two clowns and an Orchid Dottyback along with a decorator crab and starfish. I really don't want to lose anything else (not that I wanted the others to die) so I need some help and fast. I of course am doing a water change. Thoughts???
 
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I should have added that I put some of this on an algae clip lady night like always and watched the yellow tang eat some of it. When I pulled the clip off this morning it smelled like swamp water. Not sure if it's related or not.
 
Not a lot to go on. Did the fish look sick at all, have you added anything new recently, did the water smell or look cloudy, etc? pH is a little low, but unlikely to be the primary cause.
 
No one was sick and all the fish ate last night. I have not added anything in months and the water was clear. The only thing the smelled was the algae clip with the red seaweed on it
 
Sorry for your losses :( I'll throw a few questions out to see if anything is related:

Do you have a deep sandbed by any chance, and if so, possibility that it was disturbed? Any kids in the house that could have dumped anything into the tank? Was the skimmer acting normal? Do you run carbon? How are you measuring Nitrites?
 
If none of the fish showed signs of illness/injury, is it possible that chemicals from cleaning fluids or something got in the tank? Did you do a water change yesterday and is it possible that your RO unit isn't working?

Sorry for your loss. The only time I've had multiple losses was when I was away. There was a power outage that my niece didn't notice.
 
If none of the fish showed signs of illness/injury, is it possible that chemicals from cleaning fluids or something got in the tank? Did you do a water change yesterday and is it possible that your RO unit isn't working?

Sorry for your loss. The only time I've had multiple losses was when I was away. There was a power outage that my niece didn't notice.

Very likely a contaminant. Just of question of what and how. Sorry for your loss.
 
Thx all for the comments. I'm sure you know how it is to have fish for two years and then lose them without any idea why. My son didn't go near the tank. No one cleans but me and I am very careful around the tank plus I didn't clean yesterday like I was supposed to. I did a water change and do far the clowns and Dottyback are doing fine. No one has or had any tumors or spots on them. I really have no idea what happened.
 
Not sure why you have any nitrites at all. You really should have zero. Since you have nitrites are you sure your ammonia was zero? What kind of ammonia kit were you using.
 
Could an electrical anomaly kill some fish & not others?

Did you own any cucumbers or other toxic critters that might have died. Could a soft coral go spastic & release toxins?

The contaminant theory sounds possible. Were you running fresh carbon at the time? Bummer. I hope you can figure it out and rebuild with confidence.
 
Do you use RO/DI water for water changes? I only ask because I was using tap water for years without problems and then all of the sudden I had multiple animals die the day after a water change and/or water top off. That was when I made the switch to RO/DI and have not had unexpected die offs since...

The PH is a 'low,' but my soft coral tank is always 7.8 despite my best attempts and the fish and corals are always fine....

Fingers crossed that you are able to save the rest of your animals!
 
No one was sick and all the fish ate last night. I have not added anything in months and the water was clear. The only thing the smelled was the algae clip with the red seaweed on it

Thats normal. Ive noticed the same thing. I only leave it in the tank for about 8 hours.
 
is the tank drilled or running off canisters? have seen non drilled tanks wiped out after they were topped off too high, which led to no surface agitation, and that led to a lack of 02 in the tank..very sorry for your losses and know that pain all too well...good luck, tk
 
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