Several animals in the Jawaharlal Nehru Biological (JNB) Park in Bokaro city - including the tiger, hippopotamus and the African lion - are living without another mate since many a month.
This violates the Central Zoo Authority norm, according to which the animals must be kept in pairs of opposite sex.
The park has been sweating it out to keep the tigers in pairs, but the plan was hit by the death of the big cat a few years ago.
Currently, a white female tiger is housed alone in zoo for several months.
"She is in robust health and eagerly awaiting a male partner. We could discern this from her call," said a zoo worker.
The case of the hippo is similar.
The male animal was brought to the park to pair with his female counterpart.
However, the female hippo died leaving the male hippo alone.
The lioness, however, is alone in the park for other reasons.
The zoo authority has asked the park management not to keep hybrid lions.
The Asiatic lions are rare and found mostly in the Gir forest.
The zoo does not have enough funds to import the African lion from outside of the country.
"According to the zoo authority, keeping the animal single is not an ideal. The primary objective of the zoo is conservation and reproduction. Entertainment and education comes afterwards. The park management should take steps for keeping the animals in pairs," said the divisional forest officer of Bokaro Kumar Manish Arvind.
When confronted with the issue, the park officials said that search was on to find the partners for the animals.
"We have written a letter to several zoos in Madhya Pradesh and Chhattisgarh, but none of them could meet our requirement. Now, we are in touch with the zoos in south India and Delhi," said a senior officer.