1. I've lost 4 fish in the last week, 2 Julii Corys, 1 female Swordtail, 1 female Platy. The only symptom I could discern was labored breathing a day or two before their deaths - no other physical symptoms.
2. Parameters: >.25 Ammonia, 0 Nitrites, 5-10 Nitrates, 80*F, 7.2 pH.
3. This 55g tank...