Do camels have nucleated RBCs or enucleated RBCs?
Camel RBCs are anucleate [1, 2]. The dark structure seen in microscopic images is not nuclei but a network of microtubules called the marginal bands. Marginal bands cause these RBCs to adopt an ellipsoid shape. The unique shape of these RBCs possibly allows them to survive osmotic stress and is probably advantageous to a camel under extreme dehydration. 


References:
[1] Cohen, William D., and N. Barclay Terwilliger. "Marginal bands in camel erythrocytes." Journal of cell science 36.1 (1979): 97-107.
[2] Long, Charles A. "Evolution of function and form in camelid erythrocytes." Actas de The 2007 WSEAS International Conference on Cellular &amp; Molecular Biology, Biophysics &amp; Bioengineering. 2007.