The lion fitting something in it's mouth,very true,my brother had a large volitan we caught and it swam around with a fish in it's mouth for two days that was to big for it and just spat it out very dead after that time.
There is a rule of thumb to numbers in a tank,but that is not always right.
If they are not stressing about the size of their home it is all good.
I had 17 fish of many varieties in a 2 foot tank and had no worries for years.
The main problem was one here and there would try to jump out.
the main thing i noticed was that there growth rate slowed a lot.
Infact the semi i caught at a fingernail size took ten years to get to four and a half inches with adult colour.
It does deform their growth and possibly make them live far longer,if they are moved on as they get to big for the tank,it would make sense.
That tank had filtration that would sustain an eight footer,that was the main thing that kept them all healthy.
The next tank back than was a 4 footer and once matured it had 37 fish and a huge amount of inverts and it did great.
It is the bio filtration and personality (species)matching to get a mosltly stress free tank.
I caught a 6 inch volitan three days ago for the next show that the club sets up called the petacular and the next day it had the coris wrasse from the same trip in its mouth and it was bigger than it,dumb fish and i was as well for having anything in with an untried volitan.