Oh yay! I'm so happy you finally did the right thing for him!
Okay, epsom salt (as long as it's unscented and no other additives) you can use 3 teaspoons per gallon. Make sure you dissolve the salt first in another container (a small cup) with tank water. mix it around and then you can pour into the tank. The Pleco won't like it though so if you have another small container for her, that would be best.
Note: NOT with the Male, keep him away from your females or your going to get more females like this and it could eventually hurt them. You don't want your fishy friends hurt!