Hi my male Platy has been sick since Saturday. He was either lying on the bottom or gasping for air at the top. I placed him in separate container at the top of the tank. Have given bacterial medication every day since and yesterday tried a pea. He’s still no better. Just laying In the container. All my other fish are ok which Include 3 other platys. Neón Tetra and harlequins. Is it old age ? He was my first fish and was fully grown when I got him 9 months ago.