?

I'm trying to make a small above ground pond for Mom's front porch.

I found someone with metal barrels 50g, but would this be safe? ( < that is the question)

I know some metal things aren't safe for fish.

What might be going in there is probably going to be my 2 comet goldfish or some rosy minnows (If that makes any difference. I plan on plants too and have an idea for getting the light down there, will also be using some kind of bubbler thing and probably making my own filter.)

(They should hold water, they're for rain barrels.)

Serious answers only please.

Thanks.

If I were to have, lets say a barrel or something with a couple or few goldfish (probably comets), and it was in a covered area like the front porch, would it be safe to use a regular filter on it?

Like just the regular ones they have at the store?

(I'm not asking about the size or the fish, just would it be safe since the area is covered from rain and such to have 'indoor' filtration?)

Thanks!