I clean rust with dilute pool acid. About 25% acid + water. I hold the part with monofiliment fishing line. Removes rust in a few minutes. But be careful, this stuff will burn skin and eyes.

Or if you are more patient, vinegar will work.

What finish do you want on the item?
If you use a conversion coating it chemically turns the rust into a black tough (phosphate based) coating that is an excellent primer under paint.
The conversion coating works on tight rust, but there must be rust present to convert.

thanks, hook and brickeyee....

Brickeyee, tell me more....when i bought the metal fish art, I just hung it. Now, what can I do with this conversion coating? And where do i get it? Auto supply? I think the fish is pretty rusty and corroded, and quite frankly, I don't care whether I paint it or keep it natural metal, it looks fine whatever it is as a patio piece.

I guess...what would prolong it's life the longest if I don't care whether it is a painted fish or a bare metal one. And of equal importance, I do not want to sink a ton of $$$ into the fish...I'm looking for a way to keep it happy on the porch without it costing me an arm and a leg.

I appreciate it for the art, but there is no emotional attachment. The metal as the original artist has intended is now corroded, but it is not a Picasso!!! I can do whatever I care to....