Cory deaths (and not pandas)

[itiwhetu]

Salt and Cory's not a good mix

 

[Gypsum]

Yeah, the salt may be your problem. They can tolerate small amounts of salt for a short period of time, like if you're treating something, but they can't cope with it long term.

 

[Stefan3289]

So do we think the main issue was the salt that was slowly killing them of rather than a cycle crash? Are neon cardinals also sensitive to salt? I performed a water change yesterday and didn’t add salt and I plan on doing another one tomorrow.

 

[Gypsum]

Yeah, I would go with that and see what happens.

 

[Colin_T]

Post clear pictures of the fish.

That level of ammonia (0 - 0.1ppm) is not going to cause problems to fish when the pH is 6.8.

You can have tanks with 0 nitrate, it's not unheard of.

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How often do you do water changes and how much water do you change?
Do you gravel clean the substrate when you do water changes?