size isnt really the need for a bigger tank when it comes to tangs. they are highly active swimmers and grazers that need ample room, even when small, to swim. just please keep that in mind when yours starts to put some size on. as for the white stripes on his sides, they are perfectly normal. both my yellow tang and my purple tang have the same exact shaped lines on them after i turn the lines on in the am. they will eventually fade into the body once the tang is fully adjusted.