this is one of those things that will be hard, if not entirely impossible, to ever codify in an objective way.
i've had a yellow tang (Zebrasoma flavescens) and a yellow eyed kole tang (Ctenochaetus strigosus - which is a bristle tooth) in my 75. which is a 4 foot tank.
subjectively the yellow tang appears unhappy as he grows. he started around 2" in length, now is probably closer to 3.5" and to my eyes at least, looks like he wants more swimming space. he tends to hover in areas and shoot back and forth with quick bursts while flaring his fins throughout the day.
the C. strigosus was sadly killed by my yellow tang a few months after i got him. he was larger, around 3" total length or so, and had a completely different swimming style, but would still happily utilize all 4' of the length of the tank.
where the yellow tang swims more like a race car, the kole had a lopey, almost swallow (unladen European swallow to be precise) type of swim if that makes sense. where he would use his pectoral fins to pull himself around in short bursts, dipping in "altitude" in between. the yellow tang seems more tail heavy propulsion.
the 60 cube if i remember correctly is a 2'x2'x2'? i feel (again subjectively) as if that would be too much constraint, even for the bristletooth varieties. they really seem to prefer straight line areas, as opposed to having to round a corner.
side note for anyone concerned. the yellow tang will be getting a nice, new 150 gallon home come june of this year when we move.
