Dead fish help
So I have a temperate tank, with fancy goldfish, cool-tolerant Corydoras, and until yesterday a shoal of 7 beautiful Rainbow Shiners. I’m aware they’re probably the most sensitive fish in that selection.
Yesterday I visited a fish shop a few kilometres away in Spain as my LFS doesn’t stock a huge range of aquarium stuff. I bought and used Tetra Crystal Water just in that tank as it’s always cloudy, but I assume from goldfish and Corys rummaging in the sand. This morning all my Rainbow Shiners were dead. Why?
Another issue I have is I have only found 2 bodies, which means there may be another 5 fish about to start rotting and releasing ammonia. So should I leave it today, hope the Corys eat their fill, then do a massive clean out and water change tomorrow? Or should I do that tonight, though I believe peak ammonia emissions happen after 36-48 hours. I’ll never use Crystal water again for sure!