I have a freshwater aquarium (10 gallon), and it’s nice and all, but I’d like to try an aquarium with some really beautiful fish. A lot of the colorful ones are saltwater. I take care of my tank, and it’s not a big hassle. I change the water, add some chemicals, feed them, make sure everything is ok every day, and that’s about it. Is a saltwater tank significantly harder to maintain? And besides for what I just mentioned I do to take care of my freshwater tank, what additional things do I need to do to support a healthy saltwater tank?

Or would you recommend just buying a bigger tank and purchasing aggressive fish? Those seem to be really nice too. I was thinking cichlids and some others, maybe an eel too. Can peaceful fish such as my australian rainbow be put in with fish like those? Thanks, any ideas/help/comments would be appreciated.
In answer to how much I want to spend, not too much, but I don’t have a set limit. I want to make sure I get good equipment. The size I’m planning for is 55 gal. Is that a good size that will allow me some diverse fish, or is that too small? Also, as someone mentioned the lighting, is that for the coral etc., or fish? In my current freshwater tank I rarely have the lights on.