Join Date: Nov 2018
Location: Oil City PA. USA
7 is a good number but you could also add a few other small shoals of something like Ember Tetra, White Clouds, zebra Danios, and so on that would in shoals of 6 and a heavily planted tank be very flashy. You could add a shoal of Cory after the tank is established and cycled also.
This being said you need to have the tank overly filtered, so the Bio Load is cared for properly and the tank stays crystal clear.