Sick Fish, I think?

[talenzmeier]

Greetings,

I have a 58 gallon plant tank with a variety of different fish. They include 4 German Rams, 2 Bolivian Rams, 2 Angelfish, 1 Gourami, 6 Neon Tetra, 4 Gold Barbs, 4 Danios, 1 American Flag Fish, and 2 Plecos.

Today I discovered that I had three deceased Danios! I’ve also noticed that the rest of the fish seem to be breathing awfully heavily. I am worried! My [acronym:a5714d1134="Nitrite"]NO2[/acronym:a5714d1134] ≈ 0.3 (maybe a tad higher), my [acronym:a5714d1134="Nitrate"]NO3[/acronym:a5714d1134] ≈ 2.5 [acronym:a5714d1134="Parts per Million"]ppm[/acronym:a5714d1134], my [acronym:a5714d1134="Ammonium"]NH4[/acronym:a5714d1134] = 0, my [acronym:a5714d1134="Carbonate Hardness"]KH[/acronym:a5714d1134] = 5, my pH = 7.0 and my [acronym:a5714d1134="Oxygen"]O2[/acronym:a5714d1134] ≈ 12. Upon closer examination, I noticed the gills on the Danios were red. I'm not sure if the others have reddened gills, they won't sit still long enough for me to notice.

I have Fluval 304 canister filter and I'm using Carbo-Plus to add [acronym:a5714d1134="Carbon dioxide"]CO2[/acronym:a5714d1134]. I'm also using a powerhead to inject oxygen.

[Allivymar]

What's your ammonia levels ([acronym:4538409dcb="Ammonia"]NH3[/acronym:4538409dcb])? You don't list it. Red gills are often a sign of ammonia poisoning. Levels of .5 [acronym:4538409dcb="Parts per Million"]ppm[/acronym:4538409dcb] and above of nitrites can stress fish; also something to look into.

I suggest a water change [acronym:4538409dcb="As soon as possible"]asap[/acronym:4538409dcb] to reduce the levels of nitrite and possibly ammonia.