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Organic Fertilizers and Fish Feed // Use of Fertilizer in Fish Pond


 
Organic Fertilizers

Water bodies being used for fish cultivation generally fertilized by substandard organic matter that is actually waste product, like chicken droppings poultry litter, cow dung, by products of plants along with polluted waste water. Organic fertilizers including cattle dung and other plant by products can be used in fish production ponds in order to increase the production of shrimp as well as fish. Fertilization of ponds enhances the quantity of phosphates, nitrogen and other agricultural nutrients which results in the increased growth of phytoplankton. Use of chicken manure alone as fertilizer results in the good production of tilapia fish in the range of 4300kg/ha/year. Organic fertilizers have less quantity of Nitrogen, Phosphate and Potassium as compared to inorganic fertilizers. Moreover, the organic fertilizers are cheaper and results in handsome yield of crop. But their efficiency increases when they are used along with inorganic chemical fertilizers.

FEED USED

It is now accepted internationally that the increased supply of the fish products required to meet the worldly demands cannot be obtained from wild fisheries which are either declining or stagnant. To meet the National and international demands, countries around the world have developed and improved management and technologies continuously. Feed and feed management practices improved in order to increase the production volume and efficiencies for aquatic organisms in an environment of limiting natural resources.

 Suspended Solids

Suspended solids usually consist of fish waste, plankton, uneaten fish feed, or particles of clay found in water. Solid particles which remain in suspension in water are generally called as suspended solids. Large particles of clay are also found suspended in stagnant water due to negative electrical charges linked with them.

Plankton

Phytoplankton and zooplankton are generally harmless for fish but they cause turbidity in the pond water. Phytoplankton is the source of oxygen and food for zooplankton, shellfish and filter feeding fish. In turn, phytoplankton use ammonia provided by fish as source of food. In this way, both are in symbiotic relationship. Zooplanktons are used as diet for fingerlings and fry fish just like yellow perch and hybrid striped bass. Due to high usage of oxygen during respiration of algae in the night time may increase the oxygen consumption. Phytoplankton also use additional oxygenno doubt, later on they die. Any extreme change between the oxygen levels of day and night time may lead to low oxygen concentration to the dangerous level.

Fish Wastes

Trash fish or fish waste is another source of fish feed which is rich in protein. It is reported that in Viet Nam and Australia, low value fish or fish waste after processing is used frequently and results in the increased fish productivity. Fish meal is prepared by a long process of cooking, pressing in order to remove oil and at the end, drying at 70 – 100 centigrade temperature. Europe and China are the main importer of this type of fish feed.Trash fish meal is a significant feed type which is used as fish feed in order to increase the growth and productivity of fish.

 Clay

Problem of turbidity is caused by the presence of clay which is due to the exposure of soil on the pond water, open watershed, activity of crayfish or process of feeding of lower extremity fish types like catfish and carp species. Levels of turbidity more than 20,000 ppm (parts per million) may result in the change of behavior of fish in fish pond.  Value of turbidity hardly reaches to this delicate level. Even the ponds which look muddy have the concentration value more than 2000 ppm. However, clay or soil turbidity can limit the access of light frequency and checks the process of photosynthesis. The sedimentation of soil particles may cause the destruction of beneficial communities of microorganisms like bacteria .

Turbidity caused by clay can be removed by the addition of such particles which can attach to the negative charge of the clay particles, in this way, particles settles down to the bottom due to increase in weight. Common treatment for the removal of turbidity isby the addition of 7-10 square bales of the hay per surface acre or by the use of 300-500 pounds of gypsum per surface area. Gypsum should be applied periodically after two week’s interval if still pond show turbidity. Provision of live foods to fish larvae is appreciated as a significant aspect because they supply nutrition to the larvae along with the exogenous enzymes important for the digestion of other feeds and increase the development of fish larvae’s pancreas.

Supplemental Feed

The most common supplemental feed used in the province of Punjab is rice bran or rice polish. Such types of feeds are usually inexpensive, but they are low in protein content which necessitates that relatively large amount of the above mentioned feed to be fed to the fish. Simple mixture of rice bran or rice polish and any of the oilseed cakes like sunflower that is commonly available in the Punjab can also be used as feed. Productivity of ponds which are treated with fertilizers and supplemental feeds like rice polish is approximately 1.3 times greater. Mostly fish farmers utilize supplemental feed of low protein inputs such as rice polish, gluten, choker and pieces of dry bread  Addition of fish meal further can enhance the nutritive value of the food and increase the protein content of the feed. In this way, the cost of feed will increase with the increased protein content in feed. The higher cost may be offset with greater growth output and yield per unit feed intake. The farmer should maintain the records in order to evaluate the costs and profits associated with the usage of different feeds under the conditions prevailing at his own farm

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