Fish compatibility for new tank

[Natnat]

Hi! I’m setting up a new 20 gallon tank (my first). I would like to have neon tetras and fancy guppies, and would like another compatible but hardy fish to include when first starting the tank.
Any suggestions for a good fish to add to the aquarium first?
Also, how many guppies, neon tetras, and other fish csn I have in the 20 gallon tank without overcrowding (yet letting them be in a comfortable school)?
Finally, can I have male only guppies? (I don’t want them to reproduce). And how many should I have?
Thanks so much for your help!

[Aiken Drum]

How about some corys or a small loach species that will live at the substrate and provide some interest to the bottom of the tank.

You could get 6 to 8 each of the tetras and guppies and 5 or 6 panda corys.

All male guppies is the way to go if you dont want babies. Even going all female you might get fish already pregnant. Male guppies does run the risk of them getting aggressive towards each other, but with no females to fight over and a good sized group of them to spread out aggression the risk is minimised. Every individual fish and group dynamic is different though, so there are no guarantees. Only way to see for sure what will happen in your tank is to try it.

[Danio8]

I am not sure if you want to keep guppies and neon tetras together. Neon tetras are known fin nippers and may cause trouble. Maybe you try Harlequin Rasboras. I agree with getting Cories as well.

[NStalgia]

I agree with Aiken's suggestion about bottom dwellers. How about a Kuhli loach