Mrigal or Morakhi Fish Farming

The fish is called Mrigal, Morakhi or Mori fish and its farming is very popular along with two other popular carp fish species namely Rohu (Danbra or Kurero) and Catla (Thairi or Thaila). The mrigal fish is very suitable for commercial fish farming. The mrigal carp is also known as the white carp. it is native to streams and rivers in Pakistan. The fish is important in polyculture with other native fish species, especially with Rohu and Catla. The mrigal fish has become an important component in the fish farming systems of Bangladesh, India, Thailand, Laos, Nepal, Myanmar and Pakistan. It has also been introduced into China, Japan, Malaysia, Sri Lanka, Philippines, Mauritius and Vietnam. As the global food demand is increasing, so the popularity of freshwater fish species like mrigel is also increasing. Commercial Mrigal fish farming business can be a great way for earning some extra money.

The Mrigal fish has a long body, its lower body parts are straight lengthwise and its upper lip is curved downwards. The lower body part and two sides are silver coloured, back side is grey coloured. Fins are slightly orange in colour in larger specimens. They also have a pair of the trunk. It can tolerate a minimum temperature of 14°C. Its average body length is about 1m. They usually live in lower water level and feeds on small insects, organic particles and decomposed organic element etc. It gives eggs once a year during monsoon season. It is always marketed in fresh condition. It gives around 1.50-2.0 lakh eggs per kg of their weight. It is reared along with Rohu and catla fishes in equal proportions. It is a slow-growing fish but has more survival. If 10,000 fingerlings are stocked then the recovery of Mrigal fish is about 9,500. In one year it attains a weight of 600-700gm.

Mrigal fish farming is very easy and simple. One can easily raise this fish along with other fish species in a pond. The taste of Mrigal fish is excellent, so the market demand and price are also very high. It is very popular as a food fish and a very important aquacultured freshwater fish species throughout South Asia. It is widely cultured as a component of a polyculture system of 3 major carp, along with Rohu and Catla fish.

Site Selection

Try to select a site with full sun for starting mrigal fish farming business. It will also be very good to select an area which is free from noise and pollution. Also try to select a site far from the residential area, because lands far from residential areas are much cheaper.

Suitability of soil

The land which is not good for agriculture is used to make fish farm. For fish farm some points should be kept in mind such as the land should have water holding capacity. Don’t make a pond on sandy and loamy soil. If you want to do soil testing then at that land dig 1 foot-wide and deep hole and fill it with water. If the water remains in the hole for 1-2 days then it is good for fish farming but if no water remains in the hole then it is not good for fish farming. Mainly 3 types of ponds are there i.e. Nursery pond, Rearing pond and Production pond.

Pond Construction & Size

After selecting a good site, construct a pond on it. if the pond already exists then its ready to go. Natural or earthen ponds are preferred and good for commercial production. Concrete or plastic ponds can be constructed, but both of these will cost more money. The size of the pond can be any depending on available land. It is recommended at least 1 acre sized pond for freshwater fish farming business.

Seed Collection

Mass-scale seed production of mrigal fish is done in hatcheries through induced breeding now. Although riverine collection still forms the source of seed in certain small areas. Farmers should try to collect seed from trusted sources. There are many breeding hatcheries to collect the seed. Government Fisheries department hatcheries are the best source of receiving Mrigal fish seed  along with other private hatcheries.

Care of baby fish: Remove the fish from the adult fish tank with the help of a scoop or cup. Baby fish must be given a few drops of infusoria which is a liquid diet with the help of an eyedropper several times a day. After some days when they reach half an inch in size, it is placed in the new tank which has enough space for them to grow.

Rearing the Fingerlings

Initially, the fingerlings are raised in a nursery pond and then stocked in the main pond. You can stock up to 0.1 to 0.2 million fry per acre in the nursery pond. There the fries are raised up to their 10 grams body weight and then stocked in the main pond

Stocking in the Main Pond

The fingerlings are stocked into the main pond when they are large enough or reach about 10 grams of body weight.  Only the mrigal fish is not stocked in a pond but stocked with other fish species. It is very important for mrigal fish farming because mrigal fish is a bottom feeder (they consume food from the bottom level of the pond). So, stock mrigal fish with mid and upper-level fish feeders. A pond having an average water depth of 2.0-3.0 m can be stocked at the rate of about 2000 fingerlings/acre. The stocking ratio of Rohu, Catla and mrigal can be 30:30:40 respectively.

Feeding the Fish

Always feed the fish with very good quality feeds for keeping fish healthy. Applying fertilizers in the pond will help to produce a sufficient amount of natural fish feed into the pond. Although, it is needed to apply additional supplementary fish feeds for better growth of fish. Ready-made commercial carp fish feeds will be very good for this purpose.

Fertilizer management

Organic and inorganic fertilizers are used in aquaculture.

Inorganic or mineral fertilizers: It contains mineral nutrients which are manufactured in industries and material is taken from agricultural fields. It mainly includes animal manure, chicken manure and some other organic materials. Organic materials such as composts, grass, sewage, and rice bran.

Organic fertilizers: It contains a mixture of both mineral nutrients and organic matter. It is manufactured mainly by the local people, which includes farm animal waste and agriculture waste. It consists of at least one of these plant nutrients such as nitrogen, phosphorus and potassium.

Diseases

Tail and fin rot: The symptoms are rotting of the tail and fins, light white colour is seen at the corner of the fin, and then spread all around the fin and then finally falling.

Treatment: Treatment with copper sulphate @0.5% is done. The fish is drowned in treated water for 2-3 mins.

Gill rot: The symptoms are grey colour gills and then they finally fall. The breath of fish will squeeze and they come to the upper layer of water to take the breath and at the end, they will die due to breath squeezing.

Treatment: Fishes are drowned in 3-5% salt water for 5-10 min to treat from disease.

Epizootic Ulcerative Syndrome: The symptoms are ulcers on the body, fall of skin and fin and then ultimately death of the fish.

Treatment: Put 200 kg/acre of lime in water and don’t put fertilizers in the water.

White spot disease: White patches are seen on the skin, gills and fins of the fish.

Treatment: Drown the fish into formalin solution @0.02% for 7-10 days for 1 hour.

Black spot disease: Small spots of black colour are seen on the body.

Treatment: Drown the fish into picric acid solution @0.003% for 1 hour.

Argulosis: The symptoms are slow growth, loose fin and blood spots on the skin.

Treatment: Add Malathion (50 EC) @1l/acre at the interval of 15 days 3 times.

Leech: The symptoms are wounded skin and gills.

Treatment: put 1l/acre of Malathion to treat the disease.

Vibriosis: The symptoms are white or grey colour lesions found on the spleen and intestines.

Treatment: A dose of oxytetracycline @3-5gm/100lb of fish/day is given for 10 days or the dose of Furazolidone is given in feed @100mg/kg/fish for 6 days.

Furunculosis: The symptoms are darkening of the skin, enlarged spleen, rapid breathing and bloody mucous. This disease will increase the mortality among fishes.

Treatment: A dose of Sulfamerazine @150-220mg/kg fish weight/day is given for 10-14 days or the dose of Furazolidone is given in feed @25-100mg/kg fish weight/day for 10 days dose of oxytetracycline @50-70mg/kg fish weight/day is given for 10 days or the dose of Oxolinic acid is given in feed @25-100mg/kg fish weight/day for 10 days.

Red mouth disease: The symptoms are reddening of fins, mouth, throat and gill tips.

Treatment: Several antibiotics and vaccinations are available which are used to cure red mouth disease.

Harvesting

Harvesting the Mrigal fish is very difficult by using a dragnet because the Mrigal fish are bottom dwellers. Complete harvesting of mrigal fish is only possible through draining. Cast nets are also often used for partial harvesting in small and backyard ponds. Production is normally 1-2 tonnes/acre per year, with mrigal contributing about 20-25 per cent.

Marketing

The mrigal fish is generally marketed fresh in the local markets. Although, long-distance transport and marketing of mrigal fish are also possible by packing with crushed ice at a ratio of 1:1 in rectangular plastic crates in insulated vansis also practised. Try to send the fish to the market as soon as possible after harvesting. 

Handling and processing

Post-harvest processing and value-addition are almost non-existent at present in any of the producing countries. During recent years a small quantity of major carps is being exported to the Middle East, degutted and frozen.