and, that plant doesn't look unhealthy, just stretched to hell and back... repot it up to the cotyledons (little round bean leaves)and it will do just fine.
get cfl's pronto; they are cheap, and mandatory if you want to do this with any success at all. hid's are best, flouros are next in line.
as for the fish tank; unless you are going to do a 55g dwc, scrap that idea; trust me, a closet or cabinet will make you much happier, and will give you less headaches.
glass doesn't allow good air flow, and heat cannot pass through it.