hello dear student !!

There are so many good universities  in India which provide MSc  in Zoology such as Delhi university, Banaras Hindu University, Jawaharlal nehru University, Punjab university,etc. But all of them mostly takes admission  on entrance basis and even if they takes admission  on merit basis, you've  to be graduated  from the respective university  then only you  can apply for merit basis. For example,  to apply for Delhi  University  on merit basis, you have to be graduated from Delhi University  only , that too from the course Zoology. Since you have done your graduation  from Bihar so you can't  apply to these  Universities in merit based admission.  But you  can appear in there entrance  examinations. In order to apply for merit basis, there are some private universities  which are good but these are little expensive and are not as good as government  universities.  Some of them are : Lovely professional University,  Chandigarh University , Chitkara University, DAV university etc. But all of them are expensive so i would suggest  you to prepare well and  appear for entrance examination  of the respective government  universities .

All the best!