They're Goldfish, and cannot be sexed until they are over 1-2 years old.
http://www.bristol-aquarists.org.uk/goldfish/info/sexing-fs.htm
If you did have a male and female, and spawned, you'd end up with far more than one "baby"! That's if all the eggs hatch of course, you could end up with upwards of 40 "babies" (or fry).
Breeding Goldfish is challenging anyhow, they're not easy fish to breed in fish tanks and that's best left to Goldfish collectors and commercial breeders.
http://www.bristol-aquarists.org.uk/goldfish/info/breeding-fs.htm