Basil

This little bird flew into my house. I managed to get it to trust me enough so that it perched on my finger . I went outside to let it go and it wouldn't fly away. I tried to put it on branches, bushes, etc. But it won't leave. So, i just made a little nest with a towel in shoe box for it.

I need to feed it, but I don't know what or how or where I would go to figure it out. It still has a few of those downy feathers, but it can fly so... I don't know whether or not it's considered a baby. Does someone know what I should do with this bird?

So, I salvaged an old fish tank from my basment, (because new tanks are expensive) and it had a lot of calcium build up over the years of storage and spiders and dust. In hopes of restoring it, I cleaned it with white vinegar (just the kind you'd find around the house) and a scrubbing brush, hosed it down, and set it out to dry. When I came back, there was a rainbow-y residue ( kind of like when the sun hits gasoline kind of rainbow). So I hosed it down 3 or 4 more times, and the rainbow-y residue was still there...

What is it? (is it from the vinegar?)

Would fish be safe with it?

If not safe, how would you go about removing it?