Alrighty i have a 100 gallon koi pond.....with no koi lol. It has had them before but we had a bit of a racoon problem.Yeap we got at him a couple times but he always ended up getting away. I also had 3 pet bass. Very amazing. But they shared the same fate as the koi. For some reason the racoon left, or died somehow,but now i have a bluegill.I had 2, but for something happened to one of them. He got crippled out of no where like something smashed his side, and ended up dying from it.We think he got caught under the filter when we were cleaning the pond. So now theres one, and he has made a spawning bed  ;D. He gaurds it even though theres no eggs or anything.Just a gravely,sandy green spot in the middle of the moss clumps in the pond. Do you think it would be fine to put a female in there and they would mate, or would he be aggressive towards her?and do any of you know how to tell the difference between a male and a female?thanks 

Thats kind of cool. Google is your friend

http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Forum=7&topic=000214&Number=0&site_id=1#import

thanks