If you do have babies in that tank (and sooner or later you will, you will end up with a lot more fish than you can cope with. Personally, having been in that position I would only keep males. Females can store sperm for up to (I think - I'd have to check) four months, so even if you get some that aren't obviously pregnant, you can get a delightful surprise one day . . .
Are your plants plastic? I would put some real ones in.
That sounds like an excuse to start a predatory/carnivorous fish tank to me. Cichlids, bettas, etc.
	            
						
					
.  Of course, one of them may identify as a female . . . 
)
 
 since I'm very often not. But when it comes to livebearer sexing... I'm fantastic! Wait, that sounds so wrong...