Fish dying, shrimp dying, and even a crab has died (Arrow Head)

[Tcompton4]

I would recommend changing things only one at a time, so you can see what factors are at play. I personally would cease all algae treatment and ich treatment, and see where that leaves you in 3-4 days. NOPOX is varsity level chemistry, I played with that for a while and regret it. Focus on a water change and water quality. Let algae grow for now. See if it stabilizes. Nitrate is really 0? That is very odd, and not ideal. Again, I'd cease the nutrient removal stuff.

And of course it could be two things hitting all at once - like velvet on the fish. Good luck!

No, white on fish at all and no film on the ones that have died. I don’t believe the test on the Nitrate at all but two different test came out to zero (Red Sea and API). I have found normally the API is off compared to other test which is why I used two test as a double check. We just did a second water change on the tank and have discontinued all meds for the tank. Stopping the dosing for algae may not be a bad idea but I will wait a few days to change anything else. Only trying to change one item to see what is going on. Thank you for all of the advice as the stopping dosing was something I was thinking about.

 

[Tcompton4]

Which city?

Leavenworth, KS