Roadman I think quite a lot of users of this site have tropical aquariums (including me). What exactly do you need to know (although I find the internet gives better answers than random strangers unless they are real experts in the subject matter)?
I have 5 White Cloud Mountain minnow in a 25L fish tank i want to get one corydora but would it get lonely being the only corydora obviously the minnows won’t be a threat
As I said, this of the internet
"These then are hardy fish and an excellent inexpensive choice for your first cory. As with nearly all Corydoras they should be kept in groups of at least three, while more is better"