Your original sentence is mostly clear and understandable, but we can make it a little smoother and grammatically correct. Here is the corrected version:
The penguin dad keeps the egg warm by gently holding it on his feet, tucked away in his feathers, while the mother is off swimming and catching fish for her family.
Explanation:
- Since the subject is penguin dad (he), we use keeps instead of keep.
- Everything else in the sentence is correct and easy to understand!
This sentence tells us that the dad penguin carefully holds the egg on his feet and keeps it warm under his feathers, while the mom penguin is swimming to catch fish for them.