The adoption of greenhouse technology in the aquaculture of warm water fish species such as Nile tilapia in high altitude areas characterised by low temperatures is recommended in order to improve the performance of Nile tilapia.
In aquaculture, water quality stands among the most important factors influencing the survival, growth, reproduction and development of fish and the overall management of the culture systems. The main objective of water quality management in aquaculture is to have improved growth rates of fish through improved feed utilization efficiency as well as fish survival hence optimal production performance. This will eventually results into reduced production costs in terms of time and money. Deterioration in water quality can result in poor feed intake and conversion efficiency, fish are stressed and become vulnerable to diseases which can result to poor growth rates. Furthermore, the increased cost of production due to management problems are directly related to poor water quality and in severe cases it results into fish kills.
Water quality includes all biological, physical, and chemical variables which influence the beneficial use of water. Physical and chemical variables of water quality includes aspects of Dissolved oxygen, salinity, ammonia nitrogen, nitrites, nitrates, chlorine, pH, conductivity, turbidity etc. collectively, physical chemical parameters of water quality directly affects growth of fish by influencing the rates of metabolism, reproduction, life cycles and health of fish.
Temperature has been found to be critical in determining the concentration level of most physical chemical factors. Furthermore, water temperature affects all physiological processes of fish. Under natural conditions, Nile tilapia (warm water fish) production is higher in warmer season of the year when temperatures are within optimal range. In low temperature zones and seasons, the metabolic activities of Nile tilapia are usually reduced which negatively affects their growth. To improve production in such regions/seasons, supplementary heat is inevitable. There are several methods/infrastructures for thermal regulation that has been tested with various success stories being reported.
The selection of aquaculture production technology to be employed in improving thermal energy are based on their impact on water quality. In high altitude for instance, the areas are characterized by low temperatures below the recommended range of 21-29 ˚C hence not favourable for optimal growth of warm water fish species like Nile tilapia.
In such areas, greenhouse is one of the technologies used to control temperature and humidity to boost aquaculture by preventing drastic drop or rise of temperature. Furthermore, studies indicate that water temperature in greenhouses can be increased by 3-9 °C.
Current study concluded that greenhouse has a major influence on water temperature, a critical parameter for growth of warm water fish species like Nile tilapia. Mean water temperature recorded in the greenhouse pond was within the recommended temperature range. Furthermore, resultant fish weights were upto four folds in comparison to fish grown in open pond.
Source : Akidiva Alex A, Yasindi Andrew W, Kitaka Nzula. Influence of greenhouse technology on selected pond water quality parameters and growth performance of Nile tilapia in high altitude areas. Int J Fish Aquat Stud 2020;8(4):142-147.