Introduction

Fish is a very rich source of protein. In Nepal, both local and exotic species of fish are available. Fishes are naturally available from rivers, ponds, seas, and wetlands. For fish farming, a pond is necessary.

Feeding Management of Fish

Fish need nutrients. Fish farming also requires a balanced diet that includes carbohydrates, fats, proteins, vitamins, and minerals. Fish are fed differently than another animals. Food for fish is supplied in the following ways:

Application of manure in the fish pond

Manure of pigs, chickens and ducks increase production rather than the manure of cows and goats. There are many ways to apply manure such as:

1. Before stocking fingerlings in the pond: The pond is drained and cleaned after harvesting fish. Lime is applied and tilled, filled with half water and manure is spread uniformly about two weeks before stocking the fingerlings.
2. During growing period of fish: Manure is either filled in a basket or sack and placed on one or more sides of the pond. Manure is released weekly as required. If the temperature is less than 18^oC, the manure application should be discontinued.
3. By integrated farming of fish: Integrated fish farming with ducks and pigs may directly supply the fresh manure to the pond.

   

There are some special advantages of organic manure over fertilizers, which are:

• Helps to reduce seepage in ponds.
• Contains trace minerals and vitamins required for fish.
• Improves the quality of soil for the growth of planktons.
• Some of the ingredients can be directly consumed by fish.

Feeding readymade feed: Readymade feeds are important for fish farming. It supplies balanced nutrition to the farmed fish. Feed are put in a flat feeder, possibly a clay pot, suspended with a strong rope and placed at one or more places in the pond. Feed is required only to supplement a balanced diet and to administer medicines.

Preparation of Balance Diet from Local Materials

Fish can find natural food by themselves under ponds. Daily, maximum 5% of their body weight is supplemented from outer sources. We can buy readymade feed from the market or prepare ourselves from rice bran, soya cakes, maize, flour, etc. While making a balanced diet for fish, we must include nutritious foods. Sources of nutritions include:

Carbohydrates and Fat: Carbohydrates are the main source of energy. The main sources of carbohydratesarerice, maize, barley, and wheat.

Minerals: Minerals are important for the body to stay healthy. The sources of minerals are common salt, bone meal, oyster cells, and readymade mineral mixtures. Calcium and phosphorous are required in a large quantity.

Proteins: Proteins are large, complex molecules that play many critical roles in the body. The main sources of proteinsare soybean, mustard seeds, leguminous crops like cowpeas, grams, lentils, peas etc.

Vitamins: Vitamins are organic compounds which are needed in small quantities to sustain life. Vitamins are found in both plants and animals. Most of them are found in feed ingredients.

Lifecycle and Reproduction Management

Reproduction depends on fish. Every fish do not have same reproduction system. The length time also varies depending on the type of fish. The lifecycle of fish depends on the species. In general, fish progress through the following cycle stages:

Eggs: Fertilized eggs develop into fish. Due to some adverse environmental conditions, disease and predators, most eggs do not survive to maturity.

Larval fish: Larval fish live with a yolk sac attached to their bodies.

Fry: When the yolks are fully absorbed, the young fish are called fry during their first month. It is ready to eat on its own.

Juvenile: After fry starts developing from fry to mature adult and gains reproductive capacity, it is called a juvenile. Most of them do not survive.

Adult: This is fully developed and sexually active stage. Fish start to reproduce.

Spawning: Female fish release eggs into the stagnant water and male fish fertilize eggs by releasing milt. Some fish spawn many times in fixed season each year while other spawns only once and then die.

Production Management

Fish contains high nutritional value and is a very good source of fats. It is also used as decoration in an aquarium. We can manage this by collecting following data of fish keeping up to date:

• Capital goods record
• Income and expenditure records
• Fish production records
• Growth record of fish
• Pond preparation cost

Diseases of Fish

Fish gets diseases due to several reasons like infection, metazoan, unicellular parasites. Some of the most common diseases are as follows:

Fin rot: A fish with fin rot will have ragged, frayed fins. Both the fins and the tail may be affected. If left untreated, the fins will eventually erode away and the infection will spread to the body of the fish. It is brought on by poor water conditions, injuries or poor diets.

Gyrodactylus: It is a parasitic infection. It can be treated by adding sulfuric acid in a small amount of fish. The symptoms are sluggishness, fin-drop, flashing color etc.

Ulcers: An ulcer is a discontinuity or break in a bodily membrane. A major symptom is theloss of appetite. We must keep the ponds clean for its prevention. Apply topical medication to the affected area of fish for treatment.

Trichodina: Trichodina is a genus of ciliate protists. Red patches and cloudy appearance on skull and gills are seen. It can be controlled through salt treatment.

Black spot: Small dark spots are seen in the fin and the body. It is also a parasitic infection.

Ichtyophthirirus: Main symptoms are scratching on head and white spots on the whole body, cloudiness on eyes and fins are slow. It can be controlled through salt treatment. The pond should be clean for prevention.

Proper sanitation, feeding, and salt treatment are good practices for the prevention of fish diseases.