I don,t think that a hippo tang kept in a 30 gallons will ever become large. I saw one kept in a 38 gallons and it was only like not even 3 inches tail incluede and it was more than 2 year old.

I know that with discus it is very easy to stunt them. If they don't eat enough in the first year they will remain like 2 or 3" at max instead of 8" to 10". Sometimes a well developing fish catch a disease and stop eating for like 3 to 4 weeks and that's enough for that discus to remain small all of its life.

I had a powder brown tang that I had for 14 years that grew to about 7 inches.
I had an orange shoulder tang that grew to about 9 inches in about a year and a vlamingi tang that grew to almost a foot in about a year.

The 'your tank is too small' in the case of tangs arises from the fact that tangs are swimmers and require the longer (6 feet) tanks that accommodate their needs not because the tang grows big.

Some reefers try to justify the purchase of a tang when they do not have a suitably sized tank by observing it size at the LFS. THe Pie Plate comment is meant to have the reefer visualize a larger fish in his/her small tank with the idea that they will pass on a purchase until that have a tank large enough to accommodate. it.

It is a dangerous myth to suggest that a fish will adapt in size to the size of the tank.

IMO fish are larger in the wild because they are eating every daylight minute whereas they may only be feed 1 or 2 times a day by the reefer.

http://www.advancedaquarist.com/2008...chterm=stunted

The above thread deals with the affects of putting marine angelfish in unsuitably small tanks but is equally true of tangs .

In summary it creates stress that leads to illnesses and premature death.