FYI Virgo, don't know if you know, but I have read that GT's and the like have been known to breed with acara's and produce hybrid offspring. Don't know how you personally feel about this, but just wanted to make sure you were aware of what's probably going on
My wee Gold Saum is a male, and I have seen him show some interest every now and then at the largest female acara. Right now everyone is still under 3 inches, but for now with the GS in the same tank I'm not going to keep any fry that might happen. IMO it's a real shame that I'm such a purist (or jerk) about hybrids, because I think Blue Acara's and the GT types would make very good tank mates in the larger tanks.
When my acara's were in my 75 gallon, I didn't have any very small fish, but they weren't the least bit aggressive to any other living thing in the tank. When I moved them to their own tank, they eventually started bickering among themselves quite a bit, so I ended up adding some dithers and this has really helped the squabbles.