Hey! Welcome to fish keeping! I have around 20-30 corydoras in my 60 gallon. 10 albinos, 7 blue spotted corydoras, and 10 emeralds! I am also a breeder. I have around 40 in my 2.5 gallon tank.(not even an inch long). It's been stated above to get more, but corydoras LOVE to swim through currents...