If your biryani or any rice dish becomes too salty, you can add starchy ingredients like potatoes which absorb the excess salt.
Overcooking fish can make it dry and the flesh tough whereas undercooking fish can make the fish mushy and the flesh dry. In order to get the fish perfectly cooked, cook only until it gets opaque and flakes easily with a fork.
If your dish is too spicy, you can add sugar or acidic ingredients like lemon juice or vinegar to balance out the spice Alternatively, you can also add dairy products like coconut milk, sour cream or yogurt depending on the flavor you like.
Allow eggs, butter, and other ingredients to come to room temperature before using them. Room temperature ingredients mix together more easily and produce a better result.