I have a 40 gallon season tank. All of sudden older female Clown fish seems to have buoyancy issues? Like shes' struggling to stay off the bottom? She'll move around when she sees me, but she's been on her side laying down most of the day. Almost as if she gets tired after moving for a few minutes? No signs on her body, no marks, there's one one smaller clown in the tank with her. Any thought?