my ball has developed a strange feeding behavior she will stalk the rat when she smells it in her cage but then she'll change her mind whe she gets within striking range and will even run from it if the rat approaches her.

1.sometimes she'll eat but will always run from the rat.
2.shes ate same size rats before with no problem.
3.started developing all these problems after i moved her from a 10 gal. to a 20 gal.