Shark fish is great in taste and it's believed to be good for breastfeeding mums as it increases milk supply for the new born. But shark fish also increase body temperature(heat), so one has to consume in little quantity. My mom says there are two varieties of shark fish one is paal sura(young fish), which is soft and tender and cooks in 10 mins. The other variety is kombu sura(matured fish) this variety of fish is rough and flesh is chewy and will take long to cook. So its always wise to choose small sized shark fish. Since shark fish increases body temperature when consumed it tends to create lots of gas in tummy, so in order to treat that, shark fish is always cooked with lots of garlic. Another important tip is any kind of tamarind based fish curry tastes great on the next day as the sourness and spiciness gets soaked in fish, so always make big batch of curry and reserve for next day too. Its our traditional style of making chettinaad fish cury.