My female molly might be sick! I have her in a 29 gal. with 3 platys. Ever since my black molly died she has been sitting at the bottom. She comes up and eats though. She hardly EVER swims around. Just in one spot. My water tested good. The nitrates are a little teeny weeny bit high but not bad. I can reduce those by doing water changes. What do you think is wrong with my molly? I need the help. Thanks!