Answered by Shaykh Yūsuf Badāt
Is there any islamic restriction to use fish and milk or milk made items together?
Jazāk Allāh Khayr/ Thank you for your question.
We have not come across any verse of the Qur’ān, ḥadīth or fiqh ruling, restricting consumption of fish together with dairy products. Therefore, Islamicaly, consuming both items together is mubāḥ (allowed).
This is more of a medical matter. You are to consult your doctor in reference to whether this combination is appropriate for your body or not. Some individuals are lactose intolerant while others maybe allergic to fish.
And Allāh Knows Best