That's good it is eating a lot of nori. However, if you look at things like horses and cows... it takes an incredible amount of vegetation to keep something alive. So I would definitely not stop trying to get it to eat something else, I wouldnt think a diet of only nori would suffice to get it real nice and fat.
In the wild the seaweed they are chewing up has little critters and other "stuff" mixed in with it, so they get at least a somewhat varied diet. The nori we feed is straight dried seaweed and most likely little to nothing else, so I'd like to think feeding only nori isnt meeting all their requirements.
Anyway, my 4" PBT will eat the 3mm pellets but it's pretty hard for it and I'm not sure exactly how it does it. It can only eat like 2-3 and then it doesnt eat for a while, so I think it probably just gets them past it's teeth then holds them in it's mouth for a while until they get soft enough to go down easily. Just a guess though.
My slightly larger lieutenant tang eats the 3mm pellets with gusto though, so I bet pretty soon the powder blue can as well.
And yep, my goal is to get everything onto pellets. My main food source for the fish is pellets. I mix up NLS (3mm and 1mm) and Ocean Nutrition #1 and #2 in about even parts, plus the good NLS flake. The flake is new, I have never fed saltwater fish flakes before but they really seem to like it and since it's a NLS product I trust it to be good for the fish. Anyway, I mix all those 5 things together into my auto feeder and let it feed 4 times a day, basically once every 2.5 hours. I sometimes supplement with frozen mysis, but that's about once a week, twice at the very most.
I have only had most of these fish 3-4 months so I cant comment on their long term health on a diet of only pellets, but my old 210 I had for over a year and my fish only got bigger and bigger fast and got healthy fast. At first I was feeding a lot of meat to that tank but the water quality was so hard to maintain I switched to pellets which made it a lot easier and the fish grew faster, if anything.
Tangs really seem to do good on pellets... my dussumieri went from 10" to 12" in about 2 months, only eating pellets. My little clown tang is getting bigger every time I look in the tank, it's crazy how fast he's growing and he just mows through the NLS pellets.
I have a chocolate tang which was skinny and I was a little worried about and within a week of eating pellets every day he has filled out really nicely and looks to be a good healthy fish...
Anyway, I really tout pellets as being a wonder food, nutritionally I think they are great but also for convenience. Say you get sick or hospitalized, what do you think will be easier to get someone to go feed your fish? Mysis which they have to thaw, strain and put in the tank? Or tell them to go dump 50 pellets in? And oh yeah, you can autofeed pellets to
I'm not saying dont feed other foods, by all means do, but I would definitely try to make the staple of their diet be pellets.
As far as your pbt being skeptical, give it time. Most of my fish wean over to pellets within a week, it's usually a pretty quick process, especially if you stop feeding frozen and the only thing they can get to eat is pellets. Dont let them starve, but if you keep feeding frozen a lot then they wont bother making the switch, imo.