Moving my YT from a 75 to a 90 then a 180 had no impact. I do think they grow in the first couple years then stop, regardless of environment. Although I've bought very small yellows and still nothing. Maybe I release FGI from my skin?? :)

Growth of my achilles tang in the 175g bowfront using the nori clip for size comparison

http://img.photobucket.com/albums/v2...02brad0001.jpg

and then 2 yrs later
http://img.photobucket.com/albums/v2.../april6016.jpg

and yet my powder blue tang has grown very little if at all in the 8 months I've had him in my 300g.....I wonder if position of dominance also has something to do with growth because the powder blue gets put in his place by my other 3 tangs on a daily basis

I have a yellow, kole and a naso in my 90 g, all have grown a little and eat well. What ever FGI is maybe a good thing! :lol:

I have a Yellow tang, Yellowed Eyed Kole, Hippo

Yellow has shown no growth other than getting fat (had him 3 months).
Hippo tang I got at maybe 2" and is now easily 4" (had him just over 3 months).
Kole Tang Has gotten fatter for sure but he hides anytime im near the tank so I dont see him much, but I dont think hes really grown much.

Interesting side note.

My 2 clown fish being moved from a 35gal to a 125gal have doubled in size in 4 months and show no signs of stopping.
My 6 line has grown quite a bit as well with the extra swim space.

Fish Growth Inhibitor :)

My clarkii clowns easily have grown faster than my tangs, , my female is the size of my hippo, bigger than my yellow. My hippo has grown a bit since adding, not much though. Yellow and sailfin have stayed the same, as has my blue throat trigger, all are just fatter.

I noticed the female clarkii's growth started right after moving her from the 55 gl to the 180. Maybe size does matter (tank). :lol:

That's a very interesting question.

Would say my Purple Tang is about the same size as when I got him about 11 years ago (~4"). The Regal has grown maybe 2" over the 6 years I've had him (to ~6").

To add to this, my Emperor Angel hasn't grown either.

On the dominance thing, I'd expect that could impact rate, but not sure if that would span species?

fish release a pheromone into the water column.... when this pheromone reaches a saturation point it triggers a reduction in the growth rate in the fish.....so in a way tank size can have an effect on growth rate do to the time it takes for the pheromone to reach its saturation point in a given tank.....the smaller the tank, the quicker this saturation point will be reached.....this will vary a lot of course depending on water change schedules and volumes.....diet will also play a part and so will stress.....