An investigation of the survival level of Oreochromis mossambicus fry variably kept in a closed system : laboratory experiment
This paper contains literature on tilapia culture, feeding and nutritional factors of prime consideration to survival and growth of Oreochromis mossambicus. Results are presented for a three-phase laboratory experiment on survival of O. mossambicus fry in an attempt to evaluate the use of live Spirulina platensis. The experiment was conducted on fry in a closed system in an effort to maximize the use of live Spirulina and also optimize growth and production. Fry were tested for tolerance levels of salinities, 0-35 g/lt, and showed favourable survival rates up to 15 g /lt salinity without being fed. Manipulation of input in freshwater turned high fry mortalities with increasing rates without difference for physical form of Spirulina. Growth was not significantly affected by types of input. However fry grew well at 0-40% rates with considerable survival performance. It is noted good quality of water that allow improved survival and growth of fry in a closed system may be assured with rates of input up to 5 or 10% of bodyweight. These input rates can guide use of live Spirulina in saline water tilapia culture if Spirulina proves good productivity at the consistency of fry tolerance to the salinity levels established in this paper.