A clarification of the morphological character data supporting the hypothesis of labeonin monophyly, and also for one of its subgroups, the Garraina, is presented. As an aid to ongoing studies, a full listing of putative labeonin genera is provided. Included in the Garraina is the widespread and taxonomically problematical Afro‐Asian genus Garra. Getahun (2000) in an unpublished thesis clarified much of the taxonomic confusion surrounding the African members of this genus, and we summarize many of his conclusions in the form of an artificial identification key for all 17 valid species of Garra on the African continent. The diversity of Garra in Ethiopia, the geographical centre of species diversity for the genus in Africa, is resolved and redescriptions of the six species previously recognized in Ethiopian inland waters are provided, along with formal taxonomic descriptions of an additional five new species from that country. Four of the new species are endemic to Ethiopia: Garra regressus sp. nov., Garra duobarbis sp. nov., Garra geba sp. nov., and Garra tana sp. nov., whereas the fifth, Garra dembecha sp. nov., is more widespread and found also in Eritrea, Kenya, and Tanzania in eastern Africa. © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society, 2007, 150, 41–83.

Lake Tana, Ethiopia's largest lake, has a remarkable and conservation-worthy assemblage of fish species, requiring fisheries management for sustainable exploitation. However, due to anthropogenic impacts, many of these fish species are threatened. Hence, an improved management of these resources is recommended. To allow a more sustainable exploitation of natural resources, a better understanding of the cause-effect relationships between anthropogenic impacts and environmental components is fundamental. The Drivers-Pressure-State-Impact-Responses (DPSIR) framework is a useful tool to describe these links in a meaningful way to managers and policy makers. Despite its potential, application of DPSIR is virtually lacking in developing countries. This paper assessed the potential of the DPSIR framework and used it to comprehensively describe the available knowledge and management needs in the lake catchment. Rapid population growth and the economic transformation are the main driving forces leading to various pressures such as water quality and wetlands degradation as well as declining fish community, which is detrimental to the socio-economic state and health of the local inhabitants. As feedback to the driving forces, pressures, state changes and impacts, optimal multi-level responses are developed. This study aims at providing policy makers a better understanding of the lake catchment in order to bridge the gap between science and decision-making.

This research was conducted to investigate the e¡ect of stocking density on the growth performance and yield of Oreochromis niloticus in cage culture in Lake Kuriftu. The treatments had stocking densities of 50 (50F), 100 (100F), 150 (150F), and 200 (200F) ¢sh per m À 3 . All treatments were in duplicate. Juveniles with an average weight of 45. 76 AE 0.25 g were stocked in the treatments. The ¢sh were fed a composite mixture of mill sweeping, cotton seed, and Bora food complex at 2% of their body weight twice per day using feeding trays for 150 days in powdered form. The growth performance of O. niloticus was density dependent. The ¢nal mean weight of O. niloticus ranged 147.76 AE 0.28^219.71 AE 1.42 g and the mean daily weight gain was 0.69 AE 0.01^1.15 AE 0.02 g day À 1 . Fish held in cages with lower density were heavier than the ones held at higher densities, and showed higher weight gain and daily weight gain. The most e¡ective stocking density, in terms of growth parameters, was 50 ¢sh m À 3 . The gross yield (4.52 0.55 kg cage À 1 ) showed a signi¢cant di¡erence with increasing stocking density (Po0.05). Moreover, the apparent food conversion ratio (2.48^7.22) was signi¢cantly a¡ected by stocking density (Po0.05). However, survival rate was not a¡ected by stocking density (P40.05). It can be concluded that the most e¡ective stocking densities were at 50 ¢shm À 3 cage for larger size ¢sh demand in a short period and 200 ¢sh m À 3 for higher gross production with supplementary feed.

No abstract

Fish populations of nine Ethiopian freshwater lakes were quantitatively sampled with a standardized protocol, using multi-mesh gill nets. In total, 27 species were identified, but only 14 species were common. Based on the common species, the fish communities showed large differences in their species composition, except for Lake Abaya and Lake Chamo which were similar. Most fish species were observed in only one or two lakes. Compared with the information reported in literature the present study generally underestimated the species richness. The empirical model of Amarasinghe and Welcomme (2002) for African lakes was used to estimate fish species richness, which was compared with species presence reported in literature. Biodiversity in the two northern highland lakes is low, but not lower than the model estimate. Lake Tana has a high biodiversity which is close to what is estimated by the model, but three Rift Valley lakes have low biodiversity, lower than estimated by the model. There are also strong indications for the Rift Valley lakes that species richness was higher in the past because the species richness reported in the older literature was generally much higher than those observed by us in the present study and those reported in the more recent literature. Threats like overfishing, high sediment load and degradation of habitats were identified. It is recommended that Ethiopia should develop guidelines for fishery legislation and implement it through an enforcement agency. Moreover, catchments management should be practiced to save the water bodies and their fish communities.

No abstract

An out-of-Africa dispersal route has been proposed for many organisms, including modern man. However, counter examples of in-to-Africa dispersal routes are less common. In the present article, the phylogenetic relationships within the Labeoninae, a subfamily of cyprinid fishes distributed in Asia and Africa, were analyzed to investigate the biogeographic processes governing the modern distribution of these Asian and African cyprinids. The mitochondrial DNA cytochrome b gene was used as a molecular marker. The phylogenetic analysis indicated that the subfamily Labeoninae is a monophyletic group, with some Asian labeonins located at the basal position. Two subclades were found that contained both African and Asian species, which highlighted a need for further biogeographic analysis. Based on this analysis, it is proposed that the centre of origin of the Labeoninae was in East Asia. Molecular clock estimation suggests that the Labeoninae arose by the Early Miocene (*23 MYA) during the period of the second Tibetan uplift.Subsequently, two dispersal events of labeonins from Asia into Africa occured in the Early Miocene (* 20 MYA) and Late Miocene (*9 MYA) and serve as examples counter to out-of-Africa dispersal.

Aquaculture feeds are formulated with a vast pool of ingredient to meet nutritional requirements of fish for normal physiological functions, including maintaining a highly effective natural immune system, growth, and reproduction. To ensure the dietary nutrients are ingested, digested, absorbed, and transported to the cells, an increasing diversity of non-nutritive feed additives are being used in aquatic feeds. Feed additives are supplemented in small amounts to tilapia for a specific purpose in aquaculture. Feed containing functional feed additives promote the growth and health of tilapia, improve their immune systems, and induce physiological benefits beyond traditional feeds. Probiotics, prebiotics, phytogenic substances, immune-stimulants, enzymes, hormones, mycotoxin binders, organic acids etc., are best functional feed additives to manage and regulate tilapia performance and improve aquaculture profit.