My usually voracious and active neon blue platy seems a bit off today. Didn't eat this morning and looks to have clamped fins. Isn't swimming as much either. Have a 20 gallon tank that is fully cycled. A=0, N2=0, N3=10. Last PWC/gravel vac was 4 days ago. Stocked with 4 panda corys and 3 platys. Also posted in the catfish area because one of my pandas hasn't seemed right for a couple days now. Wondering if the problem might be related?? Any suggestions on what could be wrong or for a course of treatment? Wanna keep this guys alive! Thanks!!