Any organic solvent extraction (e.g acetone/hexane) should do the trick but you will also extract a lot of other compounds if you need to purify the extracted carotene before adding to fish food that is another question all together.

Dear Anurag,

Ethanol is the most safe choice among many other used solvents to incorporate extracts into fish feed although carotene yield will be slightly lower. For more detailed information you can check the attached article.

With best wishes       SM Najim

Femi sir i think ethanol will extract beta carotene with a fair bit of yield and the advantage that we can get rid of it quickly before feed formulation.