6 month old weight 4kg

That is a good sale bird. A six month old chicken at four kilogram is strong, so price it as a heavy bird and keep it clean and active before sale. Put clear photos, mention age, weight, breed, and whether it is broiler or desi. If you want to sell it on Pashushala, use the seller page and add the bird details there. If the bird is dull, limping, or not eating, keep it aside first.