I heard that it is permitted for a sefaradi to eat fish with butter but not with any other dairy products. Is this a valid statement?
With credit to Gershon Gold for providing the link:
Nevertheless, regarding eating fish with butter (which is not considered like actual milk as opposed to other dairy products), several Poskim have ruled leniently on this matter, even according to the Sephardic custom. Indeed, Hagaon Harav Abdullah Somech zt”l of Baghdad writes that the custom in his city was to permit frying fish in butter. Thus, those who customarily eat fish with butter may continue with their custom. Ashkenazi Jews customarily rule leniently on all of the above (including eating fish with milk or cheese) and they may indeed continue with their custom as well.
It is not a valid statement. Many sefardim eat fish with milk products as they don't have that minhag. Those that do not eat fish and milk follow the Beit Yosef strictly.
Many more sefardim indeed eat fish with butter.
If a sefardi doesn't have that minhag, he doesn't have to take on that humra (stricture) -- by coincidence I checked that today with a Rosh Kollel in Bnei Brak (but didn't ask if I can quote him).
But this is much better explained elsewhere on MY.