There are some fish and chips shops in west, and the only serve fish (both halal ones and non halal). The fish are fried in oil, are we allowed to eat the halal fish with scaled even if it is cooked in same oil as fish that has no scale (like calamari)? Does contamination rule apply here, even if the fish are not najis but harram to eat? I’ve heard that Ayatollah Sistani has said as long you eat the halal fish doesn’t matter if it gets fried or cooked in same place as a non halal fish?

It is okay to eat it.