Depends on the conditions in your tank. In a brightly lit tank with limited shade, they'll never be much more than translucent lemony-white. But in a shady tank with lots of cover and a dark substrate, and ideally with peat-tinted water, their colour is (or at least appears) much richer. It's still a semi-transparent fish, but the yellow glow is much more apparent.
Cheers, Neale
how yellow do lemon tetras get? is it just the lower fins or does the body before yellow sooner or later?
or does it just stay clearish like rummy noses?