Hi, I have a 20 gallon high (hexagon shape) freshwater tank with 1 corydora, 2 ACF's & 1 Apple snail . My African clawed frog's are still small so they aren't a problem with the corydora yet but I know once they get bigger it can be a problem. I was looking to get another type of bottom feeder to help with cleaning but was given the advice to either rehome my single Corydora to someone with a shoal or separate the frogs & get more Corydora for a shoal in order to keep my Corydora happy. I don't want any of my animals to be unhappy, I've had the Cory for a year now & originally I bought him, a bushy nose pleco & 4 glow fish, but the glow fish didn't last long & my pleco died last month When I got them I wasn't told that a single Corydora is considered an unhappy Corydora. I can't add more Corydora with the frogs but I do have a 10 gallon tank setup for emergencies but I'm not sure if it's an ok size to have multiple Cories in. If u have any advice or live in the Long island Suffolk county, NY area & have a Corydora shoal & looking to adopt please let me know.