Only mammals have anucleated red blood cells, and some mammals (camels, for instance) even have nucleated red blood cells. The advantage of nucleated red blood cells is that these cells can undergo mitosis.

Is nucleus present in RBC of camel?

Like all mammals, camel's red blood cells do have the nucleus, that is they are nucleated and are oval instead of a round shape.

What animals have nucleated RBCs?

Nucleated RBCs are most often noted in dogs, cats and camelids in the context of strongly regenerative anemia. They can also be observed in camelids with regenerative anemias but even those that are not anemic but sick from various conditions.