Physio-chemical parameters of freshwater fish pond are given bellow –
Temperature
Temperature is one of the most important physical factors influencing the aquatic life. It is the basic environmental factor that effects chemical and biological reaction in water. Water temperature, a regular factor for various physico-chemical as well as biological activeties in ecosystems, is found to fluctuate markedly with the variations in air temperature. A prior knowledge of maximum and minimum water temperature of the water body is essential for fish culture. Ideal temperature 24°C to 30°C holds good for fish culture in pond.
Turbidity
Turbidity refers to the decreased ability of water to transmit light caused by suspended particulate matter and phytoplankton. 20-30 NTU is suitable for fish culture.
pH
The water tend to be more alkaline if it possesses more carbonates and less alkaline when possesses large quantities of calcium, bicarbonates and CO2. However, it is more often governed by the photosynthetic activities of producers in lakes. The hydrogen ion concentration (pH) of water is considered as an index of environmental conditions. Better fish production could be possible in pond water with pH value ranging between 6.5 to 9.0. pH is an important limiting factor in fish culture. It indicates the acid base balance of the water. The survival and growth of fish is also depending on pH of the water. The ideal pH for the growth of fishes is between 7.5 to 8.5, above and below this is stressful to the fishes.
Dissolved oxygen (DO)
Dissolved oxygen is the most crucial factor for the growth and survival of fish. The optimum concentration of DO in pond waters is 6 to 9 mg/l. Dissolved oxygen is a measure of amount of gaseous oxygen dissolved in an aqueous solution that plays a vital role in the biology of cultured organisms. Of all the dissolved gases in water, oxygen is the most important for the survival of organism under aquaculture. The minimum concentration of DO is 4 mg/l should be maintained in fish ponds
Free Carbon dioxide
Free Carbon dioxide was significantly inversely correlated with DO. An inverse relationship between DO and Free Carbon dioxide in fresh water bodies was also reported by many scientists. Free Carbon dioxide in water is the byproduct of metabolism. More than a particulate level, carbon dioxide in water is toxic to the life in water. The water supporting good fish population should contain 5 mg/l free carbon dioxide.
Alkalinity
Alkalinity is the sum of negative ions reacting to neutralize hydrogen ions when an acid is added to water. Concentration of alkalinity will be taken care by proper liming. The ideal value for fish culture is 50- 300 mg/l.
Total hardness
Hardness of water depends on the dissolved solids and pH. Hardness gives a measure of the total concentration of the divalent metallic cations like Calcium, Magnesium and Strontium. Proper liming can rectify the hardness. The ideal value of hardness for fish culture is 30-180 mg/l.
BOD
The Biochemical Oxygen Demand is the amount of oxygen taken up by micro-organism that decomposes organic waste matter in water. This is an indication of both sewage and industrial pollution. The optimum BOD level for aquaculture should be less than 10 mg/l.
COD
The Chemical Oxygen Demand of water represents the amount of oxygen required to oxidize all organic matter, biodegradable and nonbiodegradable by a strong chemical oxidant. This is an indication of both sewage and industrial pollution. The ideal value of COD should be less than 50 mg/l for fish culture.
Chloride
According to Trivery and Khatavker (1986) chloride value should be ranged between 10- 25 mg/l.
Phosphate
Phosphate although present in very small quantity in water is important for the production of phytoplanktons, which forms food for fishes.
Nitrate
Nitrate is not toxic to aquatic animals even in large concentrations. Its favorable range is 0.1 to 4.5 mg/l.
References
- Boyd CE (1982) Water quality management for pond fish culture. Elsevier Science Publishing Company, New York.
- Boyd CE and Pillai VK (1984) Water quality management in aquaculture. CMFRI, Spl. Pub. 22:1-96.
- Dhawan A, Karu S (2002) Pig dung as pond manure: Effect on water quality pond productivity and growth of carps in poly culture system. The International Centres for Living Aquatic Resources Management (ICLARM) quarterly, Manila 25C1: 1-14.
- George MG (1961). Observations on the rotifers from shallow ponds in Delhi. Curr. Sci.30: 268-269pp.
- Sharma RC and Kumar K (2002) Conservation and management of lakes of Garhwal, Himalaya. In eco logy and conservation of lakes, reservior and rivers. ABD publishers, Jaipur. India. 2:562-580.
- Sarwar SG and Wazir MA (1991). Physico-chemical characteristics of freshwater pond of Srinagar (Kashmir). Pollut. Res.10(4): 223-227.
- Trivery RK, Khatavker SD (1986) Phytoplankton ecology of the river Krishna in Maharastra with reference to bio-indicators of pollution. Asian Environ 31-42.
- Zweigh RD (1989) Evolving water quality in a common carp and blue tilapia high production pond. Hydrobiologia 171: 11-21.