Im going 2 put fresh water fish witch ones idk yet.
I have a cray and 2 tri-color sharks aka balla sharks
i want a few diffrent type
also this is the kit im geting http://www.thetankaquariums.com/product_info.php?products_id=6
but for 175 bucks and then 30 bucks in free fish
theres nothing wrong with a 55 gallon... get a mated pair of apistogramma that would look real nice. a good filter is an emperor 350 or 400. personally i like to have a filter on each side (and even in the middle on bigger tanks) so 2 350's would work well for you.