kkContact Mr. P.Ganesan. He is professor in Tamilnadu fisheries university. He will guide you. His number is 9965344330.
But you need to find agents in your surrounding area for marketing.
Fish farming is profitable only if you have 4 or 5 ponds.
Investment varies for freshwater and salt water fish farming. Freshwater fish farming needs less investment.
All the best !!!