I just got a Dalmation Lyretail Molly and at first it was fine but now it will just lay on its side one the bottom for a while. Then it will swim around fine for a while then repeat over again. Checked the water ammonia and nitrites were 0 along with nitrates as well. Any ideas would be great. Also have s rainbow shark and female Betta that are doing fine. It’s s 20 gallon cycled tank.