Three days ago, I added a platy to my tank of one Molly fish. I've had the Molly fish for four months, but I've never seen him swim in circles. Two days ago, he started swimming in circles every few minutes (twirling). I had hopes that he was just playing around, but since he's been doing it for two days now, I'm concerned. I checked the water quality and everything seemed to be fine. I don't believe it's ich because neither of the fish have white spots. I also don't think that he has swim bladder disease because he swims normally other than the whirling. Could it be stress? They are in a small-ish tank (I hope to move them to a thirty gallon soon). Again, he is twirling every few minutes. The platy fish doesn't twirl at all.
Am I just overreacting?
Am I just overreacting?