there is no minumim lenght, there are opinions on what people think the minimum lenght should be but if you want to get technical 2 miles is the minimum lenght. this is what they commenly forage in the wild, but thats also when they have to look for food, when you feed them they can have a much smaller area.

I feel size is a factor, and the narrower your tank the longer it should be, but I know in my tank mine doesent look agatated (what does that look like anyways) it is fat and it swims gently and no chalontly (*SP) unless the kids scare him/her :eek: now I also have a lot of flow and it is in random currents and the fish get a heck of a lot of exercize moving around the tank (the first two days were halarious watching them learn the currents). My tank is 3 foot long but it is also 2 foot wide so there is a fair amount of open swimming area also. one thing I do recomend is to throw out the old 40 gal min for a yellow tank and replace it with 75 and up.

Steve

my yellow tang was a complete space cadet, it made the one on Finding Nemo look brainey. It zipped around my 55g tank for a year and a half. One day it just quit eating and 4 days later it was dead. It still had a round fat belly though and no sign of parasites.