Most active is an understatement I had 24 at one point in my 125g. It was a never ending tornado. Just their movement kept my Dempsey in hiding. It took the relaxation out of watching my tank so they went to auction .Giant danios are about the most active schooling fish out there. I'd recommend creek chubs but they're native and not sure how they'd do with Corys, mine are always parallel schooling in the current and beg for food.