Been cyclling 26 gallon for 35 days and nitrates are 50 and nitrties are 1, ammonia been 0 for a week. Been using 6 tetras and 2 cory during cycle and am very concerned. One of the tetras looks super fat but still eats, like it is prego. Tonight 3-4 of them seem to be swiiming real fast up and down, I know it's the water. What I have done so far is, changed filter cartridge one week ago (left 2 inch piece of old in it, it stunk so bad I had too), have done a few water changes, 30% last night with 1/2 gravel clean. Water looks dirty for last 3-4 days and I have used Amquel that Gunnie suggested once but it looks like it is for ammonia and I am good there. Suggestions, like water changes back to back days, I am afraid I am losing fish. My water is ok out of the tap and I just can't control the nitrates and nitrites. Helppppppppppppppppp.