I have 4 guppies in a 4 gallon BiOrb. My one guppy doesn't move much anymore. It just sits down at the bottom of the tank or on top of a plant. I was told that I chose all males and that there were no females so I don't think it is pregnant. I haven't seen it eat recently either. It swims every now and then but when it does it looks like it takes a lot of effort to move. I don't know what to do!