My guess is that you might have spread it to the male while you were doing water changes without knowing it. I try to make sure I'm pretty much sterile after touching the sick ones, but Winston had an injury on his forehead that turned into a white speck on his forehead not long ago... I treated it quick and he's fine, but I'm thinking I might have gotten the bacteria into his tank by mistake.
Definitely test your water though, you never know what could be in the city supply.
Winston~ Damian~ Twitch ~ Evans