Abstract Chronic stress poses a challenge to aquaculture, with cortisol and glucose traditionally used as stress markers. Recent doubts about the reliability of scale cortisol as a chronic stress determinant have surfaced due to its role in calcium homeostasis. While cortisol affects gene expression in stress responses, its impact on metabolic pathways in cultured Nile tilapia remains understudied. We explored the connection between cortisol signatures of chronic stress in Nile tilapia and t...
Abstract Background. Aquatic insect community structure is dynamic due to threats by anthropogenic activities coupled with changing climatic conditions. The insect’s survival is dependent on the substrate, water quality, and environmental effects. The changes in water quality influence their distribution and abundance and are reflected in spatial and temporal trends. This study sought to document the effects of spatial variation on aquatic insects in Winam Gulf of Lake Victoria, Kenya. Mat...
Abstract Naromoru is a semiarid area in Central Kenya, occurring on the leeward side of Mt. Kenya. Its water sources include a few permanent rivers such as Nairobi River, intermittent streams and a large number of undrainable water reservoirs. Most of the undrainable water resources have been stocked with fish but their utilization for fish rearing has generally remained very low. The purpose of this study was therefore to examine the water quality status of the dams to assess their suitabil...
Globally, Fish feeds account for 40% to 60% of the operating costs in any aquaculture production system. There has been need for the government to promote fish culture to attain sustainable development goals of zero hunger. The study aims at analyzing the cost effectiveness of on farm formulated fish feeds in relation to commercial fish feed for sustainable aquaculture production in Kenya a case of Vihiga County. The objectives of the study are: To examine the profitability level of using on-...
ABSTRACT One Hundred And Eighty samples of True big-scale fish (Brycinus macrolepidotus Valenciennes, 1850) were collected bi-monthly from June November, 2017, from River Ogun, Nigeria. Total length and body weight of all samples measured and samples were grouped based on length into sizes: juveniles (10-14.9 cm), sub-adults (15.1-19.9 cm), and adults (20.2-26.3 cm). Significant differences (p
The pilot study on fish composition and diversity of Apodu reservoir, Malete, Nigeria was carried outbetween January to May 2017 using cast and gill net. A total number of 3333 fish, comprising 8 familiesand 17 species were recorded. Brycinus nurse were most dominant for the period of study contributing29.31% and Auchenoglanis occidentalis, least abundant made up of 0.03% of total catch. Other familiesand there percentage contribution in the total catch were Mormyridae (34.14%); Cichlidae (15...
The in vivo activities of inulin and ascorbic acid were evaluated experimentally via using 450 Nile tilapia (Oreochromis niloticus) that were distributed into 3 equal groups (each of three replicates). Fish of the first group served as a control and received a balanced diet free from inulin and vitamin C. The second fed on balanced diet supplemented with inulin (5 g kg1), whereas, the third one received a balanced diet supplemented with vitamin C (500 mg kg1). The survival and growth perf...
The purpose of this study was to examine the effect of some immunostimulants and probiotics on the survival rate, final weight, and disease resistance of overwintered tilapia fry. There were five treatments: T1 (control) fed a balanced diet (35% protein) without additives. Treatments 2 to 5 were fed diets supplemented with 4% garlic, 4 g/kg Echinacea, 4 g/kg Organic Green or 4 g/kg Vet-Yeast, respectively. Growth and resistance to disease challenge with Aeromonas hydrophila and Pseudom...
This study was conducted in order to evaluate the potential bene¢t of Bacillus pumilus and a commercial product (‘Organic Green’TM) as a probiotic in the culture of the tilapia nilotica. Two doses of B. pumilus (106 and 1012 g1 diet fed) and Organic GreenTM (1 and 2 g kg1 diet fed) were used as feed additives and administered for periods of 1 (groups 2, 3, 4 and 5 respectively) and 2 (groups 6, 7, 8 and 9 respectively) months; group 1 served as a control. Each group consisted of...
A total of one thousand Oreochromis niloticus held in earthen ponds of the WorldFish Center were used in this study. Forty of these were randomly collected from the ponds and subjected to bacteriological and pathological examination where a variety of 80 bacteria were isolated. Among those 15 bacterial isolates were examined for their probiotic activity through studies performed in vitro and in vivo. Aeromonas hydrophila, Citrobacter freundii, Pseudomonas species and two Gram-positive isola...
Three dosage levels of black seed, garlic and commercial Biogen were administered for three months in summer and six months in winter to test their stimulation effect on growth, survival and response to challenge infection in Oreochromis niloticus. At the end of summer, no significant difference was observed in the growth performance of O. niloticus with most treatments, but the level of non-specific mortalities was reduced in all treatment groups compared to the control group. Significant...
The probiotic activity of two bacteria (Bacillus subtilis and Lactobacillus acidophilus) was evaluated by its effect on the immune response of Nile tilapia (Oreochromis niloticus), beside its protective effect against challenge infections. Furthermore, their in-vitro inhibitory activity was evaluated. The in-vitro antimicrobial assay showed that Bacillus subtilis and Lactobacillus acidophilus inhibited the growth of A. hydrophila. The B. subtilis inhibited the development of P. fluorescen...
To evaluate the effect of some immunostimulants on growth performance parameters, survival rate and diseases resistance of Nile tilapia fry reared under different stocking densities, a total number of 2250 Oreochromis niloticus fries (0.3 ±0.05 g) were stocked at (2, 4, and 6 fry/m3) and provided with dietary supplementation of (Garlic 40 g/kg, purpurea extract 4 g/kg, Organic GreenTM 4 g/kg and Vet-YeastTM 4 g/kg of the diet) for a five-month period. The obtained results indicated that, sto...
This work aimed to investigate the role of some immunostimulants and probiotics in improving the response of overwintered tilapia to Aeromonas hydrophila vaccine. In this study, 15000 Nile tilapia fry (Orechromis niloticus) were collected and divided into five groups. Group 1 was the control, groups 2 to 5 were fed diet supplemented with garlic, Echinacea, Organic GreenTM and Vet-YeastTM respectively for 5 months. Vaccination with A. hydrophila bacteria was done by the end of the feeding e...
Our aim was to detect potential pathogens in diseased tilapia that might account for the high summer mortalities observed in Egyptian fish farms. To this end, diseased fish were examined from eight farms in different areas of the Nile delta. Here, we report the detection of Aeromonas species and, for the first time, the presence of TiLV in Egyptian tilapia aquaculture.