Since yesterday i noticed that my bronze corydoras was very inactive. Today when i feed them food i saw him only standing there doing nothing( he went crazy before after food). I noticed also that his puppils are very big. I had another corydoras for about 3 days ago. My water parameters are 0 on amonia, nitrites, nitrates, ph 7.5 water temperature 28 degrees celsius/82 f. Can it be bacterial infectation and if so what can i do?