Opinions!

[MaisyDawgThirteen]

I have a 10 gallon tank. It has:
-1 Male Guppy, all his friends died. :( He thinks he is a rasbora. LOL He is small, has recurring fin rot and is silver.
-2 Female Platies, one is small and skittish, other is huge and eats a lot
-5 espei rasbora, these look like harlequins but are much smaller.
-Topfin 20 filter
-Topfin 100W heater
-lots of silk Plants, a large cave and a few decorations

What do you guys think I should do with this tank? Add a female betta?

[ChoclateBetta]

Might work but some females are very aggressive.

[Freyja]

It depends on the female so have a back-up in case it doesn't work out. I tried putting my daughter's female VT in the community tank with the platies and she started chasing and nipping everyone so back she went to solitary, which is a 2.5g long all to herself.

[MaisyDawgThirteen]

I decided to leave it as it is for now. The remaining guppy is getting pretty old now, so I suspect I won't have him for much longer. When all the present fish are passed I will probably make it into a sorority.