Performance Of Nile Tilapia Oreochromisniloticus (L) In Cages of Varied Stocking Densities

Abstract

Philemon Nsinda, Benedicto Kashindye, Magreth Musiba, and Amon Shoko

Cage culture is a new venture in Tanzania, and the knowledge of stocking density in cages is still needed. Growth performance of Nile tilapia, Oreochromis niloticus (L) stocked in cages of varied stocking densities and their impacts on waters were evaluated for 212 days in Shirati Bay of Lake Victoria. We started with fingerlings of 18.0±2.1 g, 19.9±14.7 g, and 18.5 ± 8.0 g mean weights. They were raised in cages at stocking densities of 70 (Treatment I), 100 (Treatment II), and 130 fish/ m3 (Treatment III) each in triplicates. We recorded monthly fish weights and lengths, total nitrogen, total phosphorus, ammonia, and micro-benthos. Parameter such as dissolved oxygen, pH, temperature, and transparency were all monitored weekly. The final average fish weights were 374.1±59.8g in treatment I, (194.8 ± 63.7g) in II, and (273.2±20.6g) in III. Percentage fish survival was the highest in treatment I (76.7%), followed by II (65.4%) and III (54.3%). Specific growth rate, production and yield was the highest in treatment I, and significantly different from treatments II and III (p <0.05). This indicates that Nile tilapia flourished well in the lowest stocking density. Water quality parameters were within the range of fish culture throughout the study and observation of water depth, distance from the shoreline, and the prevailing water currents showed lack of adverse environmental effect caused by fish cage culturing.

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