I've been working as an advisor for the fish club at my workplace, a state prison with about 3,000 inmates, for around four months now. This program has been running for seven years, and we're the only one in the state so far. I've been impressed by the inmates' knowledge of fish-keeping, but there's also a lot of trading and overstocking going on behind the scenes. Some of these guys keep fish together that you wouldn't even think of pairing, yet they rarely lose any fish. Their tanks are always spotless, with more than enough filtration to handle the load.
I visited the prison yesterday and saw something that left me stunned. One of the inmates had a 29-gallon tank filled with mbuna cichlids and green corydoras, all living in perfect harmony. The corys were even swimming at mid-level, blending in seamlessly with the cichlids. I didn't see any fighting or chasing, just peaceful coexistence. Some of the cichlids were quite large, while the corys were relatively small. This setup has been working for two years now.
I'm not going to lie, I was baffled by this. I don't condone this kind of stocking, but it's interesting to see that it can work in some cases. I wish corys were more compatible with other fish, as I love them, but I wouldn't dare try this myself. The inmates can be quite stubborn when it comes to changing their stocking strategies, so I keep trying to persuade them to adopt more conventional methods.