I recently purchased a used hexagon acrylic aquarium. It is more tall than it is wide and it is about 40 gallons. If I did put some fish in there it would be a bigger depth range for them than the width. I want a fish that like to dive really deep and go up . What sort of fish do that? or prefer that? I think aquarium is at least 3 feet tall.

Also, would you know what soft of lighting type , bulb, is best(most powerful) for the 3 foot tank, if I were considering putting some plants on the bottom or half way on a branch?

discus and angels do great in tall tanks...

if you want to add plants, i would get some t5's or metal halides...