Wow! Did you do something bad in a previous life? My cbb, dwarf angels (flame and bicolor) and regal tang are model citizens.It's more a question of what you morally and ethically feel is an appropriate amount of discomfort for the fish. Those fish will have no problem living for years in that tank If you find the right food balance related to slowing the growth rate and also filtration for water quality. I have had a 4 inch zoa eating blue regal tang, nem eating copper banded, and a coral eating coral beauty in my 40 gal sump for about a year now trying to find a good home for them. You know the fish aren't happy about it but they look as good as the day they went in there.