Hi, My friend has set up a 125l tank and so far has 3 guppies, 3 platys, and 5 cardinals. Just wondering which other fish would go well as I am not that familiar with those fish myself.
Corydoras are a fine addition to any peaceful community tank. They add a lot of interest to the bottom and are active and fun to watch. If he can find a bristlenose pleco, that would be a good choice as well. These are becoming more readily available and are quite popular.
Just tell him to take his time and let the tank get well established first.