Title Fisheries Part-7.pdf ✅

www.iaritoppers.in Whatsapp : +91-9694095242 Page | 1 Fisheries 4 th Edition 2023-24
www.iaritoppers.in Whatsapp : +91-9694095242 Page | 2 Murrel Culture in Ponds Introduction:  Murrel belongs to the family “Channidae” and is also called as snake-head fish.  Murrel is one of the indigenous air breathing fish; there is a suprabranchial accessory respiratory organ in the murrel head. It can even survive in lower dissolved oxygen levels. This fish is identified by its dark brown colour with light black stripes over the body.  Murrel is predatory inhabit and feed on variety of fauna present in the water. However, the high demand and high market value and their capacity to withstand in adverse weather conditions make them suitable candidate species for aquaculture. The most important aquaculture species of murrel in India is the striped murrel (Channa striatus), the great snakehead murrel (Channa marulius) and the spotted snakehead (Channa punctatus).  The culture technology is standardized for striped murrel. Murrel has high demand and high market value in India. Local names of murrel fish in India:  Murrai (Hindi), Korameenu, Koramatta (Telugu), Viral meen (Tamil), Korava, Vatton, Varal (Malayalam), Cheng, Shol (Bengali), Maral (Marathi), Hal (Assamese) and Gadisha (Oriya). Salient features:  High value food fish in India and can be marketed in live condition  Murrel culture can be done in small backyard, shallow or community ponds  Value added products like fillets, pickle, curry etc. have high demand Grow out:  Pond size of 0.1-0.2 Ha is ideal for grow-out of striped murrel, with a water depth of 1 to 1.5m.  For grow out culture, the advisable stocking size is 5-8 cm or more with a stocking density of 10000/ha. The expected growth in a year is 600-700gm over a period of 8-10 months.
www.iaritoppers.in Whatsapp : +91-9694095242 Page | 3 Seed:  Weaned fingerlings of equal size 5-8 cm or more can be stocked in pond. Feed requirement:  As murrel are carnivorous, good quality protein rich pellets can be given to the weaned fish.  Feeding can be done at the rate 5% of the body weight of fish during the initial period and 2-3 % during the later stage of culture. Harvesting of fish:  Harvesting can be done when the fish reaches to a size of 600-700 gm. Marketing:  Murrel fish demand is very high in the market and can be sold in open markets at Rs.400-500 per kg. Consumer preferences, lucrative market value and their ability to withstand adverse water conditions make them suitable candidate species for freshwater aquaculture.  It can be sold in live fish markets and hence it increases the interest among the customers. Recirculatory Aquaculture System (RAS) Introduction:  Recirculatory Aquaculture System (RAS) is a technology where water is recycled and reused after mechanical and biological filtration and removal of suspended matter and metabolites.  This method is used for high- density culture of various species of fish, utilizing minimum land area and water.  It is an intensive high density fish culture unlike other aquaculture production systems.  Instead of the traditional method of growing fish outdoors in open ponds and raceways, in this system fish are typically reared in indoor/outdoor tanks in a controlled environment.
www.iaritoppers.in Whatsapp : +91-9694095242 Page | 4  Recirculating systems filter and clean the water by recycling it back to fish culture tanks.  The technology is based on the use of mechanical and biological filters and the method can be used for any species grown in aquaculture.  New water is added to the tanks only to make up for splash out, evaporation and that used to flush out waste materials. The reconditioned water circulates through the system and not more than 10% of the total water volume of the system is replaced daily.  In order to compete economically and to efficiently use the substantial capital investment in the recirculation system, the fish farmer needs to grow as much fish as possible in the inbuilt capacity.  The management of recirculating systems relies heavily on the quantity and quality of feed and the type of filtration. Numerous filter designs are used in recirculating systems, but the overall goal of all filtration is to remove metabolic wastes, excess nutrients, and solids from the water and provide good water quality for the aquatic organisms. It is important to consider all factors when designing and investing in aquaculture systems. How RAS Works:
www.iaritoppers.in Whatsapp : +91-9694095242 Page | 5 Advantage of RAS:  Extended durability of tanks and equipment  Reduced dependency on antibiotics and therapeutants hence, advantage of getting high quality fish.  Reduction of direct operational costs associated with feed, predator control and parasites.  Potentially eliminate release of parasites to recipient waters.  Risk reduction due to climatic factors, disease and parasite impacts  RAS production can promote flexibility in terms of location for farming, proximity to market.  Enable production of a broad range of species irrespective of temperature requirements.  Feed management is considerably enhanced in RAS when feeding can be closely monitored for 24 hrs.  Exposure of stock to stress on RAS can be reduced for some factors such as adverse weather, unfavourable temperature conditions, external pollution and predation.  Enable secure production of non-endemic species.  Judicial use of water and land areas Disadvantage of RAS:  Constant uninterrupted power supply is required if electric power fails than backup of electricity is required  Capital cost of starting a recirculating aquaculture system is high as compared to ponds and raceways. Species suitable for RAS:  Baramundi/ Asian Seabass/Bhetki (Lates calcarifer)  Cobia (Rachycentron canadum)  Silver/Indian Pompano (Trichinotus Blochii/ Trichinotus mookalee)  Tilapia (Oreochromis niloticus)  Pearl spot/Karimeen (Etroplus suratensis)  Pangasius (Pangasianodon hypophthalmus)  Rainbow Trout (Oncorhynchus mykiss), especially in Hilly/cold water Region