I think the growth rate can be a little overated. I notice some are more aggressive and territorial than others. tank mates should be larger and able to take a " fanging" once and awhile but not overly aggressive. I keep mine with payara, rays, aros, redhooks, black bars,dats, RCK etc. I have lost my share of armatus but not to the sudden death associated with scombs but to oher tank mates. They need enough room and tanks mates that are not skittish causing them to jet into the glass causng a lethal head injury. Overall very cool fish and worth the price. Oh yeah the teeth live up to the hype. I was moving some food away from the overflow box and he bit my finger, felt like sticking my finger in a socket, had 6-7 puncture wounds and good amount of bleeding. Defenitely one of the top 5 species to won IMO. Good luck