I have an opportunity to pick one of these fish up at the LFS for about $30 and he/she is about 5" long. First, is that an ok price for one of these at that size and second, does anyone have any experience with them? Also, what would be good co-habits for a 125 gallon tank. I've done some reading on them (that I can find) and it seems like they aren't they overly aggressive in nature. Ideals?