I guess everyone does things differently.
A friend of mine in GA has had 7 in a 55 gallon tank for 3 years now. They started out as under 2" (caught in a net when they were hunting for minnows to fish with).
Now the largest is 11", most 9inches or so. The largest one is the 'boss' of the group, no deaths in all that time (he knows about cycling a tank and added them one at a time over 2 months). He hand feeds them, says they are quite personable and not at all shy anymore. And he does 50% water changes weekly.
Mostly he keeps saltwater tanks, this is only one of 2 freshwater tanks he has. The other one is a darter tank. I wish he'd come on here and post some of his reef tank pictures. All fish he has caught while SCUBA diving.