I prefer adding a little flour dough..and then remove them after sometime. This trick also helps when there is excess salt in the dish.
Add fresh cream. ( malai ). OR Add roasted gram flour. OR Add coconut grated or coconut milk.
Taneesha I use same trick 4 excess salt, madhuchandra & Manisha thanks 4 ur tricks
I add potatoes cut in medium size ( boiled already ) They help to make the fish less sour and also become v tasty themselves.