Hi aspirant,

No, its is not mandatory.

There are many MD and MS post graduates who work after their degree.They do not enroll themselves for any fellowships.

Fellowships are not at all mandatory. Its upon your wish. Some do it to add more value to their knowledge, while some start working without doing any fellowships.

There is no assumption of success for whether you have done fellowship or not. Depends on tour skills. Initially there was no buzz for fellowships. Now a days, there is a hype for fellowships in UK AND US.

Rest all depends on your choice,

Hope that works.