I started in my small pond with 4 goldfish ( just the basic .25 cent
variety). Now I have 6 goldfish and 1 oddball that is the same size and
shape as the other small goldfish but it is a different color. It is a
murky brown/ black with a little light orange down its back.

My question is: Do goldfish have on occasion babies which are a different
color than the normal orange? If not, I have no idea where he came from.
There is no pond or stream nearby for him to have wondered in by mistake.