Control of prolific reproduction is vital for a profitable tilapia aquaculture enterprise. All‐male tilapia culture is a popular method used to control prolific breeding, because the male individuals grow faster than female and mixed‐sex populations. Presently, most farmers use 17α‐methyl testosterone (MT) to produce all‐male tilapia individuals, although synthetic hormones are linked to human health and environmental risks. Recently, considerable attention has focused on plant‐based products as alternatives to MT, because they are affordable, safe, and eco‐friendly. Despite the growing interest in using plant extracts to prevent frequent spawning in tilapia production, the available information is not collated to standardize application guidelines. Accordingly, this review article consolidates existing knowledge on the use of plant extracts to control prolific breeding in tilapia culture systems. In addition, limitations to commercial application of the extracts are identified. To date, seed, root, and leaf extracts of 20 plant species, most notably, Tribulus terrestris, Mucuna pruriens, and Carica papaya, exhibit potential for controlling unwanted breeding in tilapia production systems. The extracts are mainly administered orally, incorporated in fish feeds. Saponins and flavanoids are the main bioactive compounds in the phytoextracts, which induce sex inversion and fertility impairment in tilapia. The commercialization of plant extracts is, however, hampered by lack of standardized information on extract preparation, optimal dosages, and mechanism of action. Thus, future studies should address these technical limitations and highlight economic incentives for commercial use of plant extracts in tilapia aquaculture.

Nile tilapia (Oreochromis niloticus) aquaculture continues to significantly contribute to the growth of the aquaculture sector in Uganda. However, its production is beset by erratic and unreliable seed supply. Also, most hatcheries practice inbreeding of broodstock, resulting in inferior seed characterized by low growth rates. As such, a selective breeding program is necessary to readily avail fast-growing seed that respond to farmers’ needs. The present review consolidates available information on developing a Nile tilapia breeding program in Uganda. The article discusses the significance of genetic improvement, drawing lessons from successful Nile tilapia selective breeding programs in other countries. From a literature review, no systematic Nile tilapia selective breeding program was traceable in Uganda. Scanty information on the selective breeding efforts of the species was available, with little evidence of selection for improved performance. Overall, the national capacity for aquaculture research and development, including fish breeding and strain improvement, was weak and poorly funded. The review recommends purposive support for developing a systematic strain improvement breeding program, which will be a source of improved broodstock and seed for hatcheries and farmers, respectively. The program would guide the formulation of standard operating procedures for quality seed production towards ensuring sustainable aquaculture growth in Uganda.

In Uganda fish is a great source of animal dietary protein, however, natural stocks continue to decline. Therefore, aquaculture provides a viable option to bridge the increasing fish supply-demand gap. Accordingly, a study was conducted from March to August 2016 to investigate the effect of stocking density on the growth performance, and survival of Nile tilapia (Oreochromis niloticus) in floating net-cages to contribute to aquaculture production in Uganda. Nile tilapia fingerlings, with an average weight of 4.07 g were stocked in 8 m3 cages at three different stocking densities; 200, 250, and 300 fish/m3, and fed on a locally formulated commercial feed for 180 days. At the end of the experimental period, results showed that fish stocked at lower densities were heavier than those stocked at higher densities. The mean final weights of fish were; 150.79±85.71, 127.82±68.43 and 118.73±49.29 g in cages stocked with 200, 250 and 300 fish/m3, respectively. The mean final weight in lower density (200 fish /m3) treatments was significantly higher (P0.05) among the stocking densities. Survival rate and stocking density were negatively correlated. The best survival rate (94.19%) was obtained in low stocked cages (200 fish/m3) compared to 92.98% in highly stocked cages (300 fish/m3). The results of this study suggest that 200 fish/m3 of a cage, is the best stocking density in terms of fish growth parameters. Key words: Aquaculture, animal protein, per capita, livelihood, yield.

Cage fish farming, a recent development in aquaculture, has enhanced fisheries production due to its higher stocking densities than traditional pond and open-water systems. Although it can enhance production, the system can pose biodiversity threats when there is an unintentional or intentional release of stocked fish into the wild. In this review, we examine the expansion of Nile tilapia (Oreochromis niloticus L.) cage aquaculture in Africa and the potential threats that this may have on congeneric Oreochromis species. Threats such as interspecific competition, disease transmission and hybridisation, which are drivers of genetic diversity loss among native fish populations, have been reported. However, most studies have focused on investigating cage fish production, water quality and the associated economics, but research assessing the genetic and ecological impacts imposed by the escaped fish from cages on native species is still limited across African countries. While direct evidence of hybridisation due to cage fish farming is lacking, genetic mixing of Nile tilapia with native Oreochromis species has been reported in some African water bodies. Further, only Egypt, Kenya and Uganda have functional Fisheries and Aquaculture regulations for guiding the aquaculture activities. Thus, there is an urgent need to institute regulatory frameworks that not only provide clear guidelines on aquaculture production but also balance between environmental conservation and economic sustainability

Despite the importance of Nile tilapia as a main aquaculture species in Uganda, limited research has been conducted concerning its genetic diversity, particularly in farmed populations. This gap has hindered the development of a systematic breeding program for this species. Successful aquaculture development, especially for genetic improvement, relies on the diversity and purity of wild and farmed populations as germplasm sources for selective breeding. Using microsatellite markers, the current study evaluated the genetic diversity of 480 samples collected from 20 populations of Nile tilapia (Oreochromis niloticus) in Uganda. All the populations exhibited a higher expected heterozygosity (0.50 ± 0.01) than observed heterozygosity (0.42 ± 0.01), although this was not significantly different. Populations from ponds showed lower FST values (<0.001), an indication of lower genetic differentiation. The populations formed four main clusters; the first comprising of mainly cages (Pal and Busana), the second with cages: Katosi and SON in addition to Rocks hatchery, the third comprised of Bawe cage fish farm and Tendo hatchery, and the fourth were populations from ponds and beaches on Lake Victoria. Given the higher genetic diversity and genetic differentiation of Tendo and Rocks populations, these farms would provide potential candidates for the development of local strains in Uganda. These results provide more insights into the management of local Nile tilapia strains towards reduction of inbreeding levels.

The study was conducted to identify the constraints and potential opportunities of cage fish farming in South Western Highland Agro-Ecological Zone (SWHAEZ). 82 questionnaires were administered to six respondent groups (current cage fish farmers, potential adopters of cage aquaculture, farmers who have abandoned cage aquaculture, regional and district fisheries officers, and financial institutions) to obtain insight into the challenges in cage fish farming as well as opportunities that can be exploited to promote cage fish farming. People in relevant government institutions were also interviewed. Primary results show that lack of funds and lack of government extension services are key challenges in cage fish farming. Lack of funds incapacitates farmers’ failure to get aquaculture inputs like feed. It also accounted for the inability of potential adopters and farmers who have abandoned cage aquaculture to start or continue cage aquaculture respectively. Major opportunities identified include; availability of the market for the fish, willingness of the financial institutions to offer loans at a cheaper interest rate, availability of the extension services at the sub-county level. Our preliminary recommendations is that the government can also provide subsidies to most expensive inputs like feeds, seine-net, water testing kits and construction costs for aquaculture. There is need to empower and build capacity for the extension workers through improved good management practices like feed and feeding and record keeping.