Placental mammals reproduce externally. (not in pouches)
All foxes are mammals and reproduce internally.
Externally.
internally
externally
internally
External, like most fish.
Female goldfish have ovaries to produce eggs, and reproduce externally. Male goldfish have internal testes, and they also reproduce externally.
Dolphins reproduce internally and give live birth.
Horses are mammals and reproduce internally, and the female gives birth after a gestation period of about 335 to 340 days.
internal
Baby mammals cannot reproduce, they have to be mature.
Externally fertilize eggs.