I have a 20 gallon moderately planted tank. My ph is 7.5 and I keep the temp at 78. I currently have 5 neon tetras, 5 glow light tetras and a pair of bolivian rams. I'm looking for a fish that will stay at the top of the tank most of the time. Anyone have any suggestions? I was thinking maybe a female betta or two? Could I safely keep a male betta? I'm open for any suggestions. Thanks.