Hi, I know this may sound like a pretty silly question but being brand new to all of this I am realising I know very little. Is it better to keep the light on during the night in my tank or turn it off? I have been turning it off the last couple of nights, and this morning when I turned it back on I found my platys very listless and floating on the bottom of the tank. I have been watching them for the last half hour or so and they now they seem to be coming back to life a bit more. I know that the water is the main offender for killing fish but I am wondering whether the lights play any part in their health as well. I have already lost two cory cats and I really don't want to lose my little platys as well. Please advise as I am really worried about my little fish.