I'm making yellow curried fish over on my food blog, and that means a quick visit to the local market for the ingredients. The quality of the fish is the most important thing in that dish. The curry just adds the usual flavor, but a good meaty fish that holds it shape while cooking is essential.
Phuketians are very lucky when it comes to seafood. The fish are plentiful and very fresh and what's more very very cheap. The traditional Thai markets are the place to go shopping for fish, my fishmonger recommends these small tuna for the yellow curry, 60 baht a kilo, this one cost me 50 baht.
He guts and cleans them for free too. What more could you ask for.