A cross‐sectional study was conducted from November 2017 to March 2018 at Lake Hawassa to determine the prevalence of larval Contracaecum infestation in Nile tilapia, (Oreochromis niloticus), African Catfish (Clarias gariepinus) and Barbus species (Barbus intermedius). Fifty‐two point six per cent (52.6%) previous prevalence and 5% precision were used to estimate the sample size. Accordingly, a total of 383 randomly sampled fish species comprising of 163 (42.6%) C. gariepinus, 159 (41.5%) O. niloticus and 61(15.9%) B. intermedius were examined. The length and weight of each sampled fish were recorded. All the sampled fish were examined for the evidence of Contracaecum parasites in Hawassa University Veterinary Parasitology and Pathology Laboratory. Chi‐square values and comparison of proportions were used to analyse the data. The overall prevalence of Contracaecum parasites of fish population was 31.6%. The distribution of parasite was significantly affected by fish species (p = .000), sexes (p = .018), length (p = .003) and weight classes of fish (p = .026). As a hygienic problem and gutting activity conducted at the sides of the Lake Hawassa and distribution of discarded fish wastes for surrounding piscivorous birds by butchers and other people, the life cycle of Contracaecum parasite was perpetuated. Thus, the parasite is of zoonotic significance. Therefore, awareness creation activities for societies and control of fish parasites should be conducted in the study area.

Materials and Methods Feed ingredients collection and diets formulation Jatropha curcas seed cack, a target feed ingredient, was collected

No abstract

This research was designed to investigate the growth performance and feed utilization efficiency of juvenile Nile tilapia, Oreochromis niloticus L. fed different types of diets formulated from varieties of feed ingredients. For this purpose, six experimental diets were prepared. All the six experimental diets had soybean, bone meal and groundnut as basal feed ingredients which accounted as 60% of the total amount of ingredients. The rest 40% of each diet was 1Maiz:1Sorghumfor control diet or diet "A", coffee husk/pulp for diet "B", wheat bran for diet "C", beer sludge for diet "D", potato scrap for diet "E" and 2JCKM:1Wheat:1Rice for diet "F". After diet preparation, one hundred eighty fish having an average body weight of 3.27 g were randomly distributed into 18 aquaria (80 cm×30 cm×35 cm) in triplicates. During the experiment, the fish were fed three times a day at the rate of 10% of their body weight for 10 weeks. The results revealed that there was significant difference (p<0.05) on the growth performance and feed utilization efficiency of the fish that fed different types of experimental diets. The highest growth performance in terms of final body weight, weight gain and specific growth rate, and feed utilization efficiency were observed on the fish fed diet "A" followed by the fish fed diet "F", while the fish fed diet "B" had the lowest. The lower growth performance and feed utilization efficiency observed on the fish fed diet "B" might be due to high dietary fiber levels together with the presence of relatively higher anti-nutritional factors in coffee husk/pulp diet. However, all the fish had similar survival rate. As conclusion, except diet "B" all the tested diets are potential fish feed. However, further study should be done to evaluate the potential of those diets at later stage of the fish in different culture systems.

Nile tilapia, Oreochromis niloticus, is one of the most popular aquaculture fi sh species in the world. However, among several challenges, the presence of pathogenic bacteria causes high economic losses. Thus, the main objective of this study was to isolate and identify the potent bacterial pathogens from Nile tilapia reared at Hawassa Fish Research and Multiplication Station, Ethiopia. For this, infected fi sh samples were collected from the research station and subjected to microbiological and biochemical tests. The results of the study revealed that 75% of fi sh with the length group ranged from 14-17.9cm; 52% with the length group ranged from 18-21.9 cm and 33% with the length group ranged from 22-26.9cm were infected by different bacteria belonging to the genera Vibrio, Escherichia, Aeromonas, Pseudomonas, Salmonella and Streptococcus. Except for Streptococcus, all isolates belonged to gram negative bacteria. The bacterial population observed in fi sh organs was signifi cantly high in intestine (12.43±0.55 Log 10 CFU-1 g) than in liver (6.48±1.06 Log 10 CFU-1 g). An antibiogram test showed that isolated bacteria were sensitive to gentamycin, tetracycline and amoxicillin. In conclusion, the present results clearly indicate that cultivable fi shes are prone to infection by infectious and non-infectious and that it may affect fi sh and their product quality which leads to economic loss and livelihood of farmers who depend on small scale aquaculture.