I have a 15 gal at 75°f with a goldfish, 2 small albino plecos, 3 small Cory catfish, and 3 glofish, a pink, a blue and a longfinned yellow. My problem is with the yellow one, he chases the pink one all day and the blue one knows to stay out of his way , are thay maybe wanting to mate, are they playing , are they being aggressive. They don't have any nicks like they yellow has nipped them at all but the pink one just sits like it's tired of it. Idk how to sex them so idk what to do. There are plenty of areas for them to have their own territories. I even have like a rock shelf. I'll post a picture and if I can a video. The blue is hiding on the bottom, the pink stays pretty much where it's pictured.