Do i have too many fish in my 5 gallon tank?

The fish will get along well enough, but you have too small of a tank for them to really thrive. You should get at least a 20 gallon tank. The guppies and white cloud minnows need a lot more room to swim in. The buenos aires tetras and neon tetras are a little less active, but their size alone will dictate a larger tank than what you have. If you change to a 20 gallon tank, you will not have to change out quite so much water. 10% a week or 25% a month.