FISH FARMING

Introduction of Fish Production Fish Farming

Pisciculture or fish farming is a process of breeding, raising, and transporting of fishes for domestic and commercial purposes. Fishes top the list when it comes to healthy and nutritional food options as they are a rich source of proteins and other minerals. 

However, there are primarily three types of pisciculture. They are - Monoculture, Polyculture and Monosex Culture. 

To define pisciculture, first, you need to know its variants in detail. Let’s begin! 

Types of Pisciculture

There are mainly three types of pisciculture and different available. These are:

Monoculture – This system allows farming a single species of fish. It offers high production and quality. These fishes are popular among consumers. Usually, in India, an example of monoculture fish is shrimp. 

Polyculture – It is also called composite or mixed fish farming. Polyculture lets rearing different species of compatible fishes in a shared pond. However, their feeding habits have to be different so that each of the species can survive on different food from a common resource. It is a beneficial kind of pisciculture. 

Monosex Culture – Generally, this culture allows growing either female or male fishes of a species. This is how fishes are obtained through this culture. One example of such fish is Tilapia. 

Now that you know what fish culture is. Let’s proceed with other details. 

Fish Farming Methods

Different fish farms use different methods. Some of them are discussed below. 

Cage System – Metal cages are submersed into water that contains fish. This off-shore mode of farming allows feeding the fishes artificially. 

Pond System – In this system, people need a small pond or tank where fishes grow. It is one of the most beneficial fish farming techniques because the water containing fish waste is used to fertilise the agricultural field. 

Integrated Recycling System – This method makes use of large plastic tanks (with aeration) containing fish, placed in a greenhouse. Besides, there lies a hydroponic bed next to the tanks. Using the water from the fish tanks, people cultivate several herbs like basil, parsley, etc. 

Classic Fry Farming –Using this technique, the fishes are reared from eggs to fingerlings. Then they are released in stream water. 

These methods are essential when you write the answer to what is pisciculture

But in all these types of aquaculture, special care has to be taken of the parameters of the water (in some ways less attention will have to be paid in some). The one who has come to handle the quality of water- he only gets profit in the business of aquaculture. But handling water parameters is not such an easy task. So let's take a look at the water quality parameters.

Management Of Water Quality In Fish Ponds For Maximizing Fish Production.

Introduction

The aquatic environment governs fish life; hence water quality should be suitable for fish culture. When environmental condition does not conform to optimal range for normal fish growth, then fish culture could be affected. The major concerns of the fish culturist should be to deal with the aspects of water quality that may cause poor growth or death of fish (Boyd, 1978). Water quality management aims to regulate environmental conditions so that they are within a desirable range for growth and survival of fish. To a great extent water determines the success or failure of an aquaculture operation. The aquatic environment is composed of many aquatic variables. Fish culturist's must know the variables that are potential sources of stress for the fish. The variables may also explain the causes of fish culture problems.

Water quality management

Water quality is a dynamic web of the physical, biological and chemical factors, which constitute the water environment and influences the production of fish and other aquatic environment. There are many water quality variables in pond fish culture. All other things being equal, a pond with good water quality will produce more and healthier fish than a pond with poor quality. Water quality determines to a great extent the success or failure of a fish cultural operation (Piper et al., 1982). Water quality parameters, which are of prime importance, are mainly temperature, turbidity, oxygen, CO2, nitrogen, ammonia, pH, alkalinity, hardness, etc.

Temperature

The water temperature is considered to be one of the most important factors in aquatic environment because it affects all metabolic, physiological activities and life processes of different trophic levels of pond ecosystem. In addition, it also affects the speed of chemical changes in soil and water (Dhirendra, 2002). Water temperature plays an important role in influencing the periodicity, occurrence and abundance of phytoplankton as it had a direct relationship with total plankton (Tripathi and Pandey, 1990). Fishes are cold-blooded animal and dependent upon the water temperature in which they live. Every fish species has an ideal temperature range within which it grows quickly. The optimum temperature range for 'cold water' and 'warm water' fishes are 14-18°C and 24-30°C respectively. Water temperature can be adjusted to optimum level in controlled system such as hatcheries. It is difficult to adjust temperature in large water bodies. Operation of aerator during calm and warm afternoon helps to break thermal stratification of pond by mixing warm surface water with cool subsurface water.

On a hot summer afternoon, a dip in a cool pool might feel wonderful. On a cold winter morning, a hot shower might be preferable. In either situation, your body continues to regulate its temperature at roughly 98.6 degrees. The same is not true for fish. As cold­blooded creatures, they take on the temperature of their surroundings. This is an important concept to keep in mind if you’re considering fly fishing in Fraser, CO.

Because their bodies adjust to the temperature of the water, fish are greatly affected by fluctuations in this temperature. In fact, the water temperature can alter every aspect of their survival:

Breathing: Fish breathe by passing water over their gills. The water flows into the fish’s mouth and is forced out through its gills. Along this pathway, dissolved oxygen travels to the fish’s blood cells. However, as water temperature rises, the oxygen in the water is decreased. This makes warmer water less habitable for fish. If the temperature reaches critical levels, the fish can no longer breathe.

Reproduction: To reproduce, each species of fish has specific requirements for water temperature. If these temperatures are not achieved, the fish will not reproduce. Coldwater fish often breed at low temperatures. Salmon, grayling and trout breed at a few degrees above freezing. On the other hand, warm­water fish require much higher temperatures. Due to these preferences, a body of water that experiences a drastic temperature change inconsistent with its history can cause fish to either leave the area or reduce in number due to lack of reproduction.

Feeding; When a fish is in water that offers an optimal temperature for its body, it is most likely to feed. The fish’s metabolism, oxygen demand and activity will be functioning at healthy levels, which will encourage feeding. Since various fish prefer different temperatures, it is important for fishing tours in Fraser, CO to schedule outings at appropriate times and locations for the best results. Fishermen who wish to attempt fly fishing in Fraser, CO on their own should familiarize themselves with the desired temperatures of the fish they hope to catch and use this information to plan their days accordingly.

Mortality: While some fish prefer warmer temperatures, water that is too warm can be lethal to any fish. Higher temperatures increase the demand for oxygen and decrease its supply. As temperatures rise, toxicity of the water may also increase, as toxic substances become more soluble. Warmer water is also more likely to grow fungus, which can be detrimental to fish life.

Would you like to learn more about fly fishing in Fraser, CO and how water temperature affects this sport and its participants? For detailed information on the best times and temperatures for fishing and fish survival, contact the experts at Winter Park Flyfisher. Our experienced guides can answer all your questions and provide the fishing experience of a lifetime. Stop in today or give us a call to schedule your next fishing tour in Fraser, CO!

Turbidity.

The turbidity is a term that refers to the suspended solids particles, planktonic organism and humic substances produced through decomposition of organic matter. In aquaculture ponds, turbidity from planktonic organism is often desirable to an extent, where as that caused by suspended particles is undesirable (McCombie, 1953). However, heavy blooms limit heat and light penetration, then reducing the effective volume of productive zone. Optimum Secchi-disc visibility of fish ponds is considered to be 30-40 cm. In ponds with Secchi-disc visibility of 10-20 cm, dissolved oxygen concentration may fall so low at night that fish are stressed or even killed (Romaire and Boyd, 1978). Turbidity due to suspended solids can be controlled by application of organic manure 500-1000 kg/ha or gypsum @ 250-500 kg/ha or alum @ 25-50 kg/ha.

Dissolved oxygen

Dissolved oxygen is one of the most important chemical parameters in aquaculture. Low dissolved oxygen levels are responsible for fish kills, either directly or indirectly. The concentration of dissolved oxygen in natural water is influenced by the relative rates of diffusion to and from the atmosphere, photosynthesis by aquatic plants and respiration by aquatic biological community. Dissolved oxygen along with the turbidity could provide information about the nature of an ecosystem better than any other chemical parameters (Hutchinson, 1975). It was also observed that dissolved oxygen content of pond water in the range of 5 mg/litre to saturation level favour good growth of flora and fauna. Aeration is proven technique for improving dissolved oxygen availability in ponds. Several form of mechanical aeration are available to the fish farm e.g. Paddle wheel aerator, airlift pumps, air diffuses, agitators etc.

Carbon dioxide (CO2)

The primary sources of carbon dioxide in fish ponds are derived from respiration by fish and the microscopic plants and animals that comprise the fish pond biota. Decomposition of organic matter is also a major source of carbon dioxide in fish ponds. The fish producers are rightly concerned with maintaining adequate concentrations of dissolved oxygen. The problem with the potential toxicity of carbon dioxide can be related to the daily fluctuating pattern of dissolved oxygen and carbon dioxide concentrations. Carbon dioxide concentrations are highest when dissolved oxygen concentrations are lowest. Carbon dioxide concentrations are maximum during winter and minimum during summer. However, carbon dioxide is rarely a problem in winter because dissolved oxygen concentrations are usually well above saturation levels. Freshwater fish pond should contain a low concentration of free CO2 (<3 mg/litre), although it can tolerate high concentrations of CO2 (Boyd, 1978)Aeration and increasing of pH can control the high concentration of CO2. Experiment have shown that 1.0 mg/litre of hydrated lime can remove 1.68 mg/litre of free CO2 (Adhikari, 2006)

Carbon Dioxide exists in most natural waters. Carbon dioxide content is closely related to pH. PH decreases as carbon dioxide content increases and pH goes up as carbonate alkalinity goes up.

Carbon Dioxide exists at pH levels between 3.6 and 8.4. Carbon Dioxide cannot be found in water with a pH of 8.5 or higher. "The pH value is not a measurement of the amount of carbon dioxide in the water, but rather the relationship of carbon dioxide and bicarbonate alkalinity." (Enting Engineering Handbook.)

Carbon dioxide can be used as a means of controlling the pH of swimming pools, by continuously adding gas to the water, thus keeping the pH level from rising. Among the advantages of this is the avoidance of handling (more hazardous) acids. (Wikipedia.)

Although carbon dioxide mainly consists in the gaseous form, it also has a solid and a liquid form. It can only be solid when temperatures are below -78 oC. Liquid carbon dioxide mainly exists when carbon dioxide is dissolved in water. Carbon dioxide is only water-soluble, when pressure is maintained. After pressure drops the CO2 gas will try to escape to air. This event is characterized by the CO2 bubbles forming into water. (Lenntech.)

Carbon dioxide is essential for internal respiration in a human body. Internal respiration is a process by which oxygen is transported to body tissues and carbon dioxide is carried away from them.

Carbon dioxide is a guardian of the pH of the blood, which is essential for survival.

The buffer system in which carbon dioxide plays an important role is called the carbonate buffer. It is made up of bicarbonate ions and dissolved carbon dioxide, with carbonic acid. The carbonic acid can neutralize hydroxide ions, which would increase the pH of the blood when added. The bicarbonate ion can neutralize hydrogen ions, which would cause a decrease in the pH of the blood when added. Both increasing and decreasing pH is life threatening. (Lenntech.)

Ammonia(NH3)

Ammonia is the first measurement to determine the health of biological converter. Fish are very sensitive to unionised ammonia and the optimum range is 0.02-0.05 mg/litre in the pond water. When ammonia accumulates to toxic levels, fish cannot extract energy from feed efficiently. If the ammonia concentration gets high enough, the fish will become lethargic and eventually fall into a coma and die. In properly managed fish ponds, ammonia seldom accumulates to lethal concentrations. However, ammonia can have so-called "sub-lethal" effects such as reduced growth, poor feed conversion, and reduced disease resistance at concentrations that are lower than lethal concentrations. 

The main source of ammonia in fish ponds is fish excretion. Protein in feed is the ultimate source of most ammonia in ponds where fish are fed. Another main source of ammonia in fish ponds is diffusion from the sediment. The decomposition of this organic matter produces ammonia, which diffuses from the sediment into the water.

There are two main processes that result in the loss or transformation of ammonia. The most important is the uptake of ammonia by algae and other plants. Plants use the nitrogen as a nutrient for growth. The other important process of ammonia transformation in fish ponds is� 'nitrification'. Bacteria oxidize ammonia in a two-step process, first to nitrite (NO2) and then to nitrate (NO3).

Aeration can also reduce ammonia toxicity. Healthy phytoplankton removes ammonia from water. Formalin may also reduce the ammonia. Proper feeding management should be maintained in fish pond. Biological filters may be used to treat water for converting ammonia to nitrite and then to harmless nitrate through nitrification process (Cole and Boyd, 1986).

Nitrite(NO2)

Nitrite is the second chemical measurement made to determine the health of the biological converter. Nitrite should not be detectable in a pond with a properly functioning bio-converter. Nitrite is produced by the autotrophic Nitrosomonas bacteria combining oxygen and ammonia in the bio-converter and to a lesser degree on the walls of the ponds. 

Nitrite has been termed as the invisible killer. It can be deadly, particularly to the smaller fish, in concentration as low as 0.25 ppm. Effective removal of organic wastes, adequate aeration and correct application of fertilizers are the methods to prevent accumulation of nitrite to toxic levels in pond culture.

Hydrogen sulphide

Freshwater fish pond should be free from hydrogen sulphide. Fish lose their equilibrium and subjected to sub-lethal stress at concentration of 0.01 mg/litre of hydrogen sulphide. Frequent exchange of water can prevent building up of hydrogen sulphide. Further increasing water pH through liming can also reduce the hydrogen sulphide toxicity. Potassium permanganate (6.2 mg/litre) is also used to remove hydrogen sulphide from the water.

pH

pH is a measure of hydrogen ion concentration in water is acidic or basic. It has direct effects on fish growth and survival of food organisms. Hence, to achieve good fish production pH of the water should be monitored regularly to ensure its optimum range of 6.5-8.5 (Banerjea, 1967). It also exerts considerable influence on toxicity of ammonia and hydrogen sulphide as well as solubility of nutrients and thereby water fertility. The generalised effects of pH on fish are presented in Table 1.

The best way to counter water pH problem is application of lime for increasing soil pH to greater then pH 6 and total alkalinity and total hardness to greater than 40 mg/litre as calcium carbonate. Calcium carbonate (CaCO3), dolomite CaMg(CO3), calcium hydroxide (slaked lime)-Ca(OH)2 and calcium oxide (quick lime)-CaO are the different lime material used. Lime should be carried out a few weeks before addition of fertilizer and stocking of fish. Agricultural gypsum (CaSO4) is applied to correct the total hardness without affecting total alkalinity. It may be also applied to correct the alkaline pH.

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pH fluctuations of aquaculture pond water.

Alkalinity.

Alkalinity is the capacity of water to neutralize acids without an increase in pH. Total alkalinity is the sum of the carbonate and bicarbonate alkalinities. Some water may contain only bicarbonate alkalinity and no carbonate alkalinity. The carbonate buffering system is important to the fish growth regardless of the production method used. In pond production, where photosynthesis is the primary natural source of oxygen, carbonate and bicarbonate are storage area for surplus carbon dioxide in the buffering system would never be limiting factor that could reduce photosynthesis, as in turn reduce oxygen production. On the other hand, by storing carbon dioxide the buffering system prevents wide daily fluctuations. Without a buffering system, free carbon dioxide will form large amount of weak acid (carbonic acid) that may potentially decrease the night time pH level to 4.5. During peak period of photosynthesis, most of the carbon dioxide will be consumed by the phytoplankton and as a result, drive the pH level above 10. Pond water with low alkalinity <20 mg /litre as CaCO3 and >300 mg/litre is unproductive. The ideal range of total alkalinity for freshwater fish pond is 50-300 mg/litre as CaCO3.

Salinity.

Salt helps to counteract handling stress, restore osmoregulation, prevent and control diseases, improve overall condition and survival of fish prior to and after transportation.

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Salinity management in aquaculture.

Hardness

Water hardness is similar to alkalinity but it represents several facts. It is important to fish culture and is commonly reported aspect of water quality. Hardness is the measure of calcium and magnesium, but other ions such as aluminium, iron, manganese, strontium, zinc and hydrogen ions are also covered. Calcium and magnesium are essential in the biological process of fish. Fish can absorb calcium and magnesium directly from the water or food. Hardness values are of at least 30 mg/litre should be maintained for optimum growth of aquatic organisms. Low hardness levels can be increased with the addition of agricultural lime.

Nutrients

Nutrient a major constituent of protein occupies a predominant place in aquatic ecosystem. Though a relatively minor constituent, phosphorous is often considered to be the most critical single element in the maintenance of aquatic productivity (Moyle, 1946). Dissolved inorganic nitrogen in the range of 0.2 to 0.5 mg/litre may be considered favourable for fish productivity and phosphorous fertility for aquatic productivity ranges from 0.05 to 2.0 mg/litre. In natural water, silicate remains in silicate form and is important structural constituent of diatoms. (Moyle, 1946). The nutrient status of both water and soil play the most important role in governing the production of plankton organism in fish pond (Banerjea, 1967). Nutrient can be increased in the ponds by adding inorganic and organic fertilizers in measured doses. However, increased levels of nutrient may be harmful; it can cause excessive plankton growth, algal bloom and oxygen depletion.

Other metals and gases

Other metals and gases may sometimes cause problems to the fish pond. Most complication arising from these can be prevented by properly pre-treating the water prior to adding it to ponds. The range of treatment may be simple as aeration, which remove obnoxious gases to expensive use of iron removal units. Normally, iron will precipitate out of solution upon exposure to adequate concentration of oxygen at a pH greater than 7.0. The ideal values of various physico-chemical parameters (Boyd, 1998) for freshwater aquaculture are presented in Table 2.

Conclusion

Water quality varies considerably at different geographical locations. Fish can use some water supplies considered impaired for human use, even some saline waters have aquaculture potential. Water quality affects growth and well being of fish. Therefore, water quality should be of great importance to the aquaculture. A high quality water testing kit is essential for measuring water quality on a regular basis. It is equally important to know how to interpret the water quality parameters that are measured to maintain the health and well being of their fish stock.

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