I just got a 50 gallon fish tank. Im thinking of putting bass,sunfish,crappies, fish like that. What do you think I should put in it, and how to keep it clean and healthy for those type of fish?

keep it clean with frequent waTER CHANGES AND ACTIVATED CHARCOAL IN FILTER MEDIA, all fish are cool to watch in the tank. remove injured or sick fish asap. good luck

from what I remember about running fish tanks; those fish are going to grow pretty big so you'll want to limit how many fish are in tank. from what you listed I'd pick two or three tops for a 55 gallon tank.

A bottom gravel filter is essential with a charcoal siphoning outside filter
every couple months you may "scrub" the water with a diatomaceous earth filter
I also used to use a siphoning gravel filter tube which sufficed for water changes