Aims of the Projects
A. Improving culture and feed of the Nile tilapia
Aquaculture is an important sector of Ghana's economy and increasingly supplements capture fisheries. In Ghana, tilapia is the major species cultured mainly in cages on the Volta lake, and in earthen ponds. Fish production in ponds remains low at 2.0t/ha annually compared to 5.0t/ha in similar systems in Asia. Despite the growth seen in aquaculture over the last decade, development of the sector is hampered by:
- High feed costs due to reliance on imported ingredients;
- Poor water quality and low quality of fingerlings;
- Lack of species diversification in Ghanaian aquaculture (tilapia production accounts for more than 80%)
Following global industry trends, increasing aquaculture production has been a major government’s strategy towards bridging the over 500,000 tonne fish deficit currently met through fish imports (about US$ 200 million annually). As a contribution to address the high feed cost, the Department’s efforts have focused on developing two environmentally and economically sustainable tilapia feed (DANIDA funded 13-P01-GHA, https://su sfeed.knust.edu.gh) using four locally available oilseed meals. The current project is manipulating the carbohydrate sources in the feed and exploring low cost techniques to improve the floatability of the diets.
Additionally, the project seeks to improve productivity in Tilapia culture by optimising the culture environment. Tilapias are tolerant to sub-optimal water quality conditions which allows them to survive for extended periods under conditions that would be detrimental to other species. However, under suboptimal conditions growth is not maximised even when the best feed and care are provided. Studies are ongoing to identify the critical water quality variables that affect the physiology and growth performance of tilapia in ponds. Guidelines for enhancing water quality for tilapia pond will be developed for fish farmers and shared with regulators.
B. Reproduction of the African bony-tongue
Attempts at diversifying aquaculture species in Ghana has been beset with challenges that hamper commercial culture. The African bony tongue (Heterotis niloticus) is a fast growing species with a high consumer preference. However, its larval stages are characterised by high mortality with poor larval nutrition identified as a critical determinant for survival. The Department is researching on environmental and physiological factors that influence reproduction of the African bony-tongue as well as develop protocols to improve larval survival and weaning diets in order to develop the species for commercial culture.