Ok so I just got back from a two day event. Before I left my aquarium was fine. I had fed them just to keep them happy. When I got back I noticed that they all on the top gasping for air. I did a PWC
and had to leave. When I got back I noticed all of my fish dead except for a few catfish and Danios. I tested the water and the Ammonia was 1.0 ppm
and my no2
was at a scary 5.0 if not more. This tank has been cycled for over a year, but now my lovely fish are nearly all dead. I need help with this! how do I return the tank to it's original state. I took some filter media from my bro's 10 gallon tank and just added it in. I will keep a close eye on the water parameters.