I have to tell you that if you do keep one again, please make absolutely sure that your tank is 100% safe and escape proof. I mean Alcatraz. It would also be wise to make a sign you can tape on the side or top of the tank that details the effects of the toxin so that if you do get bit someone knows what to do to get you proper help IMMEDIATELY. If you have any family or friends over often, make sure the tank is in a secure area of the house where children cannot access the tank. It would be wise to rig a locking latch on the lid just to protect any curious visitors or family.
My main concern with keeping one myself, would be that the octopus would find a weakness in the sealed top, escape, and my dogs would eat it. I wouldn't worry about being bit myself because I just wouldn't have my hands in the tank. You never know though. One careless moment could result in a really terrible death.
TONMO.com is the best place.