• Journal of Aquaculture
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• v.5 no.2
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• pp.143-155
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• 1992

Effects of vitamin E, C and/or glycyrrhizin in the artificially oxidized feed on the growth and on the resistance aganist Edwardsiella tarda infection to Nile tilapia, Oreochromis niloticus, were examined. The thiobarbitric acid (TBA) values of the oxidized feed were $80\~88$ mg/kg. The fingerling fish were fed the oxidized feed with or without the mixture of vitamin E (50 mg), C (60 mg) and/or glycyrrhizin ($25\~200$ mg) per 100 g of the feed for 7 weeks. The fish fed the oxidized feed with vitamin E, C and/or glycyrrhizin showed better growth than the fish fed the oxidized feed only. But growth rates among the fish fed different amount of vitamins or glycyrrhizin mixed feed were not different. Glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) levels in the serum increased only in the fish which were fed oxidized feed without vitamin E, C and/or glycyrrhizin. With the fish artificially infected with E. tarda: they showed low survival rate when fed oxidized feed and oxidized feed plus 25 mg glycyrrhizin per 100 g feed. The fish fed oxidized feed plus vitiamin E, C and/or glycyrrhizin ($50\~200$ mg/100 g), showed higher survival. These results show that the supplementation of oxidized lipids depress the growth and liver activity, while the addition of vitamin E, C and/or glycyrrhizin in the diet accelerated the growth, liver activity, and the resistance to E. tarda infection.

• Fisheries and Aquatic Sciences
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• v.22 no.11
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• pp.25.1-25.9
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• 2019

Background: Due to the continuous demand for fish coupled with decline in capture fisheries, there is the need to increase aquaculture production to meet the demand. Aquaculture is faced with high cost of feeding since fish oil and fish meal are expensive. In view of this, there are calls to explore alternatives that are cheap and reliable. Objectives: This study on Oreochromis niloticus was conducted to evaluate the effects of replacing fish oil (FO) with palm oil (PO) at 0%, 25%, 50%, 75%, and 100% on muscle fatty acid and proximate composition as well as growthrelated enzyme activities and mRNA expression. Methods: Oreochromis niloticus were fed five experimental diets (33% crude protein and 10% crude lipid) for 8 weeks. Feed had variation in fish oil and palm oil contents. After the 8 weeks feeding trial, five fish were sampled from each tank (15 from each treatment) and euthanized using an excess dose of tricaine methane sulfonate (MS-222 at 200 mg/L). Fatty acid and enzyme activities were analyzed using standard protocols. Also, RT-qPCR was used to quantify the expression levels of selected growth-related genes. Results: Fish fed 25% PO recorded the least muscle protein content and was significantly lower than the group fed 100% PO. Paired box protein 7 (Pax-7) enzyme activity was significantly higher in the group fed 50% PO compared to the groups fed 25% PO and 100% PO, while caplain-3 (Capn-3) was significantly lower in the group fed 0% PO compared to all other groups. There was a significant difference among treatments with respect to mRNA expression of Pax-7 and Capn-3. Group fed 25% PO had significantly lower mRNA expression of Pax-7, while the group fed 75% PO recorded significantly higher mRNA expression of Capn-3 compared to groups fed 0% PO, 25% PO, and 100% PO. Pearson's correlation analysis revealed that Igf-I and Igf-II mRNA expression have significant correlation with n-3 polyunsaturated fatty acids content in muscle. Conclusion: The results suggest muscle protein content could be modified if FO is replaced with PO. Also, mRNA expression of Pax-7 and Capn-3 is affected by replacing FO with PO.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.3
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• pp.173-182
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• 1997

This study is a basic research in purse seine fishery : on the behaviour of fish schools of tilapia Tilapia mossambica in the process of catch of the purse seine fishing method. The experiment was carried out for the mackerel purse seine which using of power block by fishing fleet system in the near sea of Cheju Island and as a forecast in the near future on the purse seine fishing, using of triplex net winch by one boat system in the near sea of Norway. These model purse seines were made of the scale of 1/180 of its full scale. The model purse seine test on the escaping behaviour of fish school by gap, area reducing of gap and tension of purse line was carried out in the stagnant water of experimental water tank. Designing and testing for the model purse seines were based on the Tauti's law. The results obtained were as follows : 1. When the time for the completing of pursing was 20 minutes, average swimming speed of fish school through a gap was 9.71cm/sec for powerblock seine and 9.97cm/sec for triplex seine. 2. In the case of pursing time in actual value was 20minutes, at 50 percent of the pursing, swimming behaviour of fish school in purse seine was 10% to I section, 80% to II section, 10% to III sectional direction for powerblock seine and a similar tendency for triplex seine. 3. In the case of pursing time in actual value was 20 minutes, at the time of 10 minutes have proceeded since then, area reducing rate of gap of the seine in projected front view was 63.5% for powerblock seine and 67.5% for triplex seine. 4. In the case of pursing time in actual value was 20 minutes, escaping rate of fish school by gap in projected front view was 70% for powerblock seine and 30% for triplex seine. Maximum tension of purse line was about 8.1 tons for powerblock seine and about 8.3 tons for triplex seine.

• Fisheries and Aquatic Sciences
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• v.21 no.2
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• pp.6.1-6.10
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• 2018

The intention of this study was to identify the bacterial pathogens infecting Oreochromis niloticus (Nile tilapia) and Clarias gariepinus (African catfish), and to establish the antibiotic susceptibility of fish bacteria in Uganda. A total of 288 fish samples from 40 fish farms (ponds, cages, and tanks) and 8 wild water sites were aseptically collected and bacteria isolated from the head kidney, liver, brain and spleen. The isolates were identified by their morphological characteristics, conventional biochemical tests and Analytical Profile Index test kits. Antibiotic susceptibility of selected bacteria was determined by the Kirby-Bauer disc diffusion method. The following well-known fish pathogens were identified at a farm prevalence of; Aeromonas hydrophila (43.8%), Aeromonas sobria (20.8%), Edwardsiella tarda (8.3%), Flavobacterium spp. (4.2%) and Streptococcus spp. (6.3%). Other bacteria with varying significance as fish pathogens were also identified including Plesiomonas shigelloides (25.0%), Chryseobacterium indoligenes (12.5%), Pseudomonas fluorescens (10.4%), Pseudomonas aeruginosa (4.2%), Pseudomonas stutzeri (2.1%), Vibrio cholerae (10.4%), Proteus spp. (6.3%), Citrobacter spp. (4.2%), Klebsiella spp. (4.2%) Serratia marcescens (4.2%), Burkholderia cepacia (2.1%), Comamonas testosteroni (8.3%) and Ralstonia picketti (2.1%). Aeromonas spp., Edwardsiella tarda and Streptococcus spp. were commonly isolated from diseased fish. Aeromonas spp. (n = 82) and Plesiomonas shigelloides (n = 73) were evaluated for antibiotic susceptibility. All isolates tested were susceptible to at-least ten (10) of the fourteen antibiotics evaluated. High levels of resistance were however expressed by all isolates to penicillin, oxacillin and ampicillin. This observed resistance is most probably intrinsic to those bacteria, suggesting minimal levels of acquired antibiotic resistance in fish bacteria from the study area. To our knowledge, this is the first study to establish the occurrence of several bacteria species infecting fish; and to determine antibiotic susceptibility of fish bacteria in Uganda. The current study provides baseline information for future reference and fish disease management in the country.

• Journal of Aquaculture
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• v.6 no.2
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• pp.125-132
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• 1993

To determine the effective dose of $17\beta-estradiol$ on the production of all female populations of Nile tilapia, Oreochromis niloticus, the first feeding-stage larvae were fed 0, 60, 120, 240 and 480 ppm of $17\beta-estradiol$ in the diet for 30 days. Rates of sex reversal, survival and growth of each treated group were analyzed. Effects of 3 different treatment durations, 10, 20 and 30 days, treated with 480 ppm $17\beta-estradiol$ in the diet to produce all females, were also evaluated. The incidence of female fish were clearly dose and time dependent. The female induction rate of 0, 60, 120, 240 and 480 ppm were 47.5, 86.4, 91.3, 97.0 and $100\%$, respectively. Female induction rates of 480 ppm treated for 10, 20 and 30 days were 64.2, 84.3 and $100\%$ respectively. The survival rate of each treated group was not different from the control, and the growth rates of the treatment groups decreased as the treatment duration and the concentration of the estrogen hormone increased.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.5
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• pp.677-684
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• 1998

The distribution and elimination of oxolinic acid (OA) following oral (80mg/kg body weight) and bath (20 mg/$\ell$) treatment were examined in the organs and plasma of Nile tilapia (Oreochromis niloticus) on different temperatures and physiological conditions using a bioassay method. On the analysis of temperature effect, both absorption and elimination of OA after oral administration were delayed in the group at $15^{\circ}C$. but significant difference of the peak concentrations in the tissues of the groups at $15^{\circ}C$ and $25^{\circ}C$ was not revealed. However, the changes of maximam concentration, absorption and elimination rates in the tissues of fish following bath treatment depending on different temperatures were more significantly different from the results of the studies with oral administration. The pharmacokinetics of OA in the tissues of diseased fish, the main target of drug treatment, also appeared to be distinguishable from those of healthy fish.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.4
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• pp.404-408
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• 1999

To analyze the possibility for the genetic improvement at the early period at 60 days of age in tilapia, Oreochromis niloticus. Genetic parameters on eight traits, total length (TL), standrad length (SL), head length (HL), body depth (BD), body height at the origin of dorsal fin (BH1), length from the origin of dorsal fin to the origin of dorsal fin (BH2), snout length (SNL), and body weight (BW), were estimated by sib analysis. Heritabilities estimated from sire, dam and full-sib components were moderately high in all metric traits, ranged 0.08$\~$0.70, 0.22$\~$0.41 and 0.18$\~$0.55, respectively. Those of SL from sire, dam, and full-sib component were estimated as 0.13, 0.22, and 0.18, respectively, Besides BH1, BH2 also showed high heritabilities, $h^2_s$ (0.08), $h^2_d$ (0.38) and $h^2_{s+d}$ (0.23), indicating that it would be a new production-related metric trait for selection. Among the metric traits, phenotypic and genetic correlation coefficients were ranged from 0,86 to 0.97 and from 0.90 to 0.99, respectively. Thus, genetic improvement would be possible at the early growth rate by the individual selection in tilapia.

• Journal of fish pathology
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• v.28 no.3
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• pp.145-155
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• 2015

The pathogenecity of atypical Aeromonas salmonicida was studied in healthy Oreochromis niloticus. Inoculum at concentration of $1.5{\times}10^8CFU/ml$ and $3{\times}10^8CFU/ml$ was injected into healthy fish through intramuscular and intraperitoneal injections. Experimentally infected Oreochromis niloticus showed ulceration at the dorsal musculature and trunk region in addition to black coloration, congested gills, exophthalmia, and ocular hemorrhage. Congested liver and kidney were recorded in post-mortem examination. Mortality of the experimentally infected Oreochromis niloticus reached 100% after intramuscular injection at concentration of $3{\times}10^8CFU/ml$. Histopathological investigation of infected organs was also performed. There was a focal area of bundles of skeletal musculature showing hyalinization. In addition, hyperplasia, congestion, and fusion were noticed in the gill lamellae. There was also congestion in the blood vessels in the ocular chamber. Severe congestion was also noticed in the central vein of liver associated with focal aggregation of the melanin pigmented cells in the parenchyma. Degenerative changes were noticed in the epithelial cells lining of kidney tubules. Plant extracts carvacrol and its biological precursor cymene were found to be effective in treating experimentally infected Oreochromis niloticus at concentration of 100 or 200 ppm.

• Asian-Australasian Journal of Animal Sciences
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• v.10 no.4
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• pp.439-443
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• 1997

A total of 135 freshwater fish samples (Oreochromis spp. <85> and Clarias lazera <50>) were collected from different localities (shops and fish markets) in Alexandria Province-Egypt and examined for the presence of parasitic larval stages. The obtained data found the overall mean of the infestation with encysted metacercariae was 71.1% in the examined fish. The rates of infestation with encysted metacercariae were 72.9% and 68.0% in the examined Oreochromis spp. and Clarias lazera, respectively. The highest prevalence of the encysted metacercariae was found in summer (81.8%) in case of Oreochromis spp. and in winter (92.3%) in case of Clarias lazera, all these seasonal differences are statistically significant. The rate of infestation of encysted metacercariae in the anterior third, middle third and posterior third of Oreochromis spp. was found to be 82.3%, 74.2% and 95.2%, respectively, while 88.2%, 88.2% and 91.2%, respectively, in Clarias lazera. Moreover, the rate of infestation of encysted metacercariae in eyes, gills, liver, kidney and branchial cavity of Oreochromis spp. was 91.9%, 70.9%, 20.9%, 46.8% and 32.2%, respectively. In Clarias lazera the infestation rate was found to be 47.1%, 70.6%, 8.8% and 38.2% in the gills, liver, spleen and kidney, respectively. The zoonotic and public health importance of the encysted metacercariae are causes severe visceral pain, abdominal discomfort, intermittent bloody diarrhoea and colic after consumption of inadequately cooked fish especially Tilapia spp. (Oreochromis spp.).

• Journal of the Korean Applied Science and Technology
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• v.30 no.3
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• pp.560-566
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• 2013

In this research we extracted water-soluble collagen peptide from flatfish skin and compared it with commercially available collagen peptide extracted from Tilapia scale currently placed on the market in the aspect of physiochemical property. The physical property and nutritional components of FSCP appeared almost similarly to those of TSCP, and also in calorie, FSCP marking 3.82 Kcal showed no differences from TSCP marking 3.84 Kcal. As for forming amino acids, in aspartic acid, serine, histidine, tyrosine, methionine, FSCP had higher content than TSCP, but in OH-proline, proline and alanine FSCP had lower content than TSCP. Especially the content of essential amino acids of FSCP marked 22.74% with a higher content compared with 13.64% of TSCP. In the distribution of molecular weight FSCP with 1,000 Da showed comparatively low compared with TSCP, and in emulsion property and stability FSCP and TSCP showed similar excellent trend.