if I remember correctly these things get MASSIVE, maybe I'm wrong. I thought I read an article a while back saying they get 3+ feet and are aggressive but don't quote me on that
There are a few guys on here that have them that over three feet in lenth. I got mine at 8" in July and he is around 19" now. They are omnivorous and are best housed alone. Mine will kill feeders that are left over when he is full and they have been known to kill any and all tankmates. I have only seen one that was in a community tank but most must be alone. They are very fragile when young and get stressed by light and movement easily.
I have heard from many sources that they will kill anything housed with them.
They are pretty cheap when they're small though. One of the wholesalers I visit just got some in a few weeks ago and they're $8 each. Probably $15-$20 retail.