Innovations in Indian major carp culture technology by the farmers of Andhra Pradesh, India.
Authors: Nandeesha M. 
Published: April 2021

India is one of the leading countries in the production of carps in the world. The Indian major carps catla (Catla catla), mrigal (Cirrhinus cirrhosus) and rohu (Labeo rohita) contribute most to the total reported Indian aquaculture production of more than 2 million t. Among these carps, rohu is considered to be tastier than the other two and it has high demand throughout the year, particularly during special festive occasions. Andhra Pradesh on the east coast of south India has reservoirs built for irrigation purposes and a large lake, Kolleru. Rice is a major crop in the State, but low profitability and problems in the cultivation of this crop prompted farmers to explore fish culture as an alternate by transforming paddy fields into fish ponds. Some farmers in the Kolleru lake region began to experiment with the culture of carps following the scientifically recommended practice of six species, the three Indian major carps, plus common carp (Cyprinus carpio) and the Chinese carps, grass carp (Ctenopharyngodon idella) and silver carp (Hypopthalmichthys molitrix). Farmers were able to get good fish production, but due to problems encountered in culture and in marketing of Chinese carps through long distance transport, farmers began experimentation to evolve technology for the culture of Indian carps with focus on rohu, which has the highest assured market throughout the year. Farmers innovated a simple method of fish pond construction by making trenches within the pond and using the excavated soil for building the dykes. Based on experience, farmers have also found that large ponds are best for growing market-size fish and hence the average size of pond used is around 3.5 ha in the region. As the Indian major carps are known to grow better during the second year, farmers always use stunted fish seed aged more than 6 months with an average weight of more than 100 g. The technology evolved by farmers is normally composed of rohu at more than 80% of the total stocking density with the rest being contributed by either catla and/or mrigal. The stocking density used ranges from 5,000 to 10,000 fish ha-1 and the density of fish depends on the final predicted harvested weight of the fish. Organic manure such as poultry and buffalo manure is widely used at more than 20,000 kg ha-1, with heavy application of lime and inorganic fertilizers that account together for more than 3,000 kg ha-1. Supplementary feed is provided to fish on a regular basis, i.e. de-oiled rice bran combined with various types of oil cake. Due to its relatively high cost, the percentage of oil cake used in the feed is regulated based on the growth of fish and season of the year, with the oil cake inclusion level generally kept below 30%. A new method of feeding fish using feed bags has been developed by farmers which has reduced feed wastage and increased efficient utility of the feed mixture. The total quantity of feed used is generally more than 20,000 kg ha-1 with a food conversion ratio of 2.5 -3.5. Though fish disease has been encountered with the increased intensification, various treatments have been developed that combine scientific information generated in the fisheries sector and knowledge available in the veterinary field. Generally, the size of fish at harvest is more than 1 kg and the current average production is more than 8,000 kg ha-1. Fish grown in the area are transported to various parts of the country, mostly to the eastern part. Carp culture using this indigenous technology evolved by farmers is reported to cover more than 80,000 ha in Andhra Pradesh. This farmer-innovated carp culture system has been sustained for the past three decades and they have been steadily increasing production from the system, with some farmers producing more than 15,000 kg fish ha-1. Coconut cultivation on the dykes is a popular form of integration and the income earned by farmers from this integration is appreciable.