Where can trout farming be done in India and what climate does it need?

Trout is a cold water fish, so it can only be farmed where you have a steady supply of cold, clean, well oxygenated running water, generally in hilly Himalayan regions like Jammu and Kashmir, Himachal Pradesh, Uttarakhand, parts of the North East, Sikkim and high altitude areas. Water temperature must stay cool, since warm water kills trout, so it is not suitable for the plains. Farming is usually done in raceways or tanks fed by flowing stream or spring water. If you do not have reliable cold running water, trout is not an option for you. This is a niche but valuable crop in suitable hill areas. Confirm that your water temperature and flow are right and get guidance from your state Fisheries department, which runs trout programmes in these regions.