I set up alot of tanks for friends, family, and their friends ...
always, give them a list of fish and corals to keep, based on tank size and filteration and so on.
noone, EVER, follows it.
why ? cause 99.9% of ppl see a 2" tang, and say it is indeed a small fish ! they do not realize its needs.
many ppl say ... "but the tang is only 2", when it gets bigger, I will give it to you to put in your larger tanks" but what they do not get, is that in order for a 2" tang to grow, it will need swimming room, alot of food, and good water, none of which can be met in a smaller tank ! most of the times ! a new reefer cant feed a 40G ALOT, and have EXCELLENT water ... so they will fail !
this is honestly starting to make me feel bad .... I have been reefing for over 10 years and breeding stingrays[freshwater] for 10 years before that.... I can do alot, and sense alot with my fish that many newer reefers cant ! [not bragging, please donot get me wron] which is making me think, in short future, we will either get our hobby banned, or it will have to follow some sort of licensing ! my LFS, who is also a friend, is a very nice guy, and cares for fish ... he often refuses to sell bigger fish to ppl with smaller tank, but at the end, he cant do much !!! if the customer wants it, he has to sell it ....
sorry about the rant ....