Fish Farmer Guide (Everything You Need To Know)
To culture fish, one has to consider the properties of the water used because it plays a major role in the growth and development of fish. Fishes perform all their biological function in water including feeding, excretion, and reproduction, maintaining salt balance, growth, and respiration. For this reason, it is important for a fish farmer to assess the physical and chemical of water for him or her to achieve the desired aquaculture. The survival and death of aquaculture are determined by the water properties such as quantity, source, physical and chemical properties, physical features, and water balance in aquaculture.
- Physical Features of Water
- Density – the density of water is very specific and it increases when the water cools up to a temperature of about 39oF. When water cools below 39oF it freezes to ice. The formation of ice increases the volume of water which will then allow the ice to float instead of sinking. This helps in preventing ponds from freezing to solid state.
- Size of the body of water – water is capable of retaining large amounts of heat with negligible temperature changes. Living organisms in water cannot tolerate rapid temperature fluctuations. The larger the ground of water the slower the rate fluctuations of temperature.
- Dissolved chemical – water dissolves many chemical substances that are beneficial to aquatic life.
- Water Balance in Fish
Fish use gills to eliminate waste products from their bodies. Gills are permeable to both salt and water. In saltwater fish consumes large amounts of water while excreting small amounts of salt-concentrated urine. Conversely, in freshwater salt is removed through the gills and water enters the fish through the skin and gills. To avoid diffusion of water into their bodies’ fish excretes large concentrations of water through the kidneys. The understating of this concept of conserving water balance in freshwater allows fish farmers to learn the benefits of using salt transport in fish.
- Water Source
The selected source of water for fish production influences the negative environmental and chemical factors. The source is selected basing of quality and quantity of water required. Some of the sources include lakes, wells, rivers, municipal water, and groundwater. Springs and wells are considered as high-quality sources.
- Quantity of Water
The least amount of water required for one-acre ponds is 13 gallons per minute. This large amount of water is needed to replace the water lost through evaporation due to heat and seepage into the groundwater. The minimum water flow rate when culturing fish in raceway should be at least 500 gallons per minute.
- Physical properties of water
Physical characteristics of water include the following:
- Temperature – it is a very important factor that affects aquatic life. Fish are cold-blooded animals and their temperature is similar to environmental temperature. The temperature of the water plays a major role in growth, activity, reproduction, behavior, and feeding of fishes. Different fish are adapted to different temperature, for example, cold water, warm water, and cool water species.
- Clay soil – it causes turbidity and it is contributed by soil and watershed exposure, feeding of bottom aquatics such as crayfish, catfish, and carp. Turbidity may suffocate fish’s eggs, block light from penetrating and interfere with the rate of photosynthesis.
- Plankton – zooplanktons or phytoplankton. They are sources of food to the fish and when they accumulate in large quantities they are likely to cause turbidity.
- Fish’s waste products – they are a source of poor quality of water. They contain large amounts of nitrogen which irritate the gills of the fishes.
- Suspended solids – include wastes, clay particles, and plankton
- Chemical Characteristics of water
Photosynthesis is important in phytoplankton. It is the process by which aquatic plants convert carbon dioxide in the presence of chlorophyll to produce food and oxygen.
- Dissolved Gases
These are gasses found in water solution and they include ammonia, oxygen, nitrogen, and carbon dioxide. Their concentration in water is measured by milligram per litre or parts per million. Oxygen is a very import factor that supports the life of fish in water. Fish die due to lack of sufficient dissolved oxygen. Fish excretes ammonia to the water.
- Buffering Systems
Buffering system is essential for preventing wide changes in pH which is important for aquaculture. pH fluctuations are caused by carbon dioxide produced by respiring plants and animals.
- pH – acidity and basicity of water
- Alkalinity- this is the ability of water to neutralize dissolved acids without causing changes in pH.
- Hardness – Hardness is the measure of magnesium and calcium in the water. Maintenance of at least 20 parts per million of water hardness is recommended for aquatic life. The level of hardness is increased by the addition of lime.
- Other gases and metals – hydrogen, iron, sulfide, and sodium affect the development of fish in ponds.