How to differ loop animation for the instances of Game Object

Hi,

   I have a question regarding how to make animation loop for different frames for instances.

    I have created instances of fish, that I have imported from unity asset store. It has loop animation of one cycle of a swim. I want to initiate instances of fish with different frames for one cycle of a swim in order to overcome the uniformity. I tried with creating instances at different timings but of no use. Please let me know how to proceed with this. Thanks in advance.