I don't know if I am putting this in the right place, I apologize. I have a 20 gallon long. Fake plants. Mix of sand/gravel substrate. It will have 6x diamond tetras, 2x ghost shrimp, and 1x mystery snail. I am still cycling it so it doesn't have these yet. My friend is giving me the snail and I will buy the rest. (I have 1 diamond tetra and 1 ghost shrimp now.. bought before I understood how to properly set up tank, so doing a fish in cycle). I will not add them all at once. My daughter really wants the colorful guppies. A few questions before I tell her okay - 1) Most important - Will guppies be okay with this set up? 2) We don't want to deal with babies. Can I have just male guppies and if so, how many? Would one or two be okay? 3) If I have to have females to keep them healthy and happy, how to prevent babies? Thanks! Edit: I keep reading about aerators.. I don't have one. Do I need one?