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

• Ecology and Resilient Infrastructure
• /
• v.5 no.2
• /
• pp.105-109
• /
• 2018

The main objective of this investigation was to examine oxygen consumption and ammonia excretion within cultured catfish, Silurus asotus ($22.9{\pm}0.9cm$, $100.7{\pm}11.7g$ n = 30) by noise and vibration stress in aquaculture farm. The vibration of 48, 58 and 68 dB (V) and noise of $77.6{\pm}1.8dB$ (A) from an electric vibrator was turned on for 15 minutes during each hour each day(0800-1800) for 11 days experimental period. The oxygen consumption (OC) of S. asotus the beginning of the experiment (0 day) in 58 dB group after 1, 5, 9 and 11 days was decreased 21.8, 30.2, 36.0 and 53.2%, respectively. In 68 group after 1, 7 and 11 days was decreased 22.7, 35.1 and 57.7%, respectively. The OC decreased exponentially and the relationship between them was expressed as OC = 0.374D + 90.762 ($r^2=0.048$) at 48 dB, OC = -3.581D + 89.520 ($r^2=0.831$) at 58 dB and OC = -4.109D + 90.907 ($r^2=0.884$) at 68 dB. Ammonia excretion (AE) of the beginning of the experiment in 48, 58 and 68 groups after 1 day was increased by 34.8, 51.8 and 63.2%, respectively, but it was decreased significantly from 3 to 11 days. The AE increased exponentially and the relationship between them was expressed as AE = -1.646D + 115.915 ($r^2=0.265$) at 48 dB, AE = -8.230D + 122.132 ($r^2=0.750$) at 58 dB and AE = -7.086D + 123.690 ($r^2=0.614$) at 68 dB.

• Journal of fish pathology
• /
• v.19 no.3
• /
• pp.227-233
• /
• 2006

Olive flounder immunoreceptor DAP10 homologue cDNA was cloned from a peripheral blood lymphocytes (PBLs) cDNA library. The length of the olive flounder DAP10 cDNA is 473bp and it contains an open reading frame of 234bp. The predicted polypeptide sequence is 78 amino acids, consisting of a 22-amino acid leader, an 11-amino acid extracellular domain, a 21-amino acid transmembrane segment, and a 24-amino acid cytoplasmic domain. The amino acid sequence of olive flounder DAP10 has 56%, 50%, 32%, 31%, and 31% sequence identity with zebrafish DAP10, catfish DAP10, cattle DAP10, rat DAP10 and Monkey DAP10, respectively. Olive flounder DAP10 has a conserved aspartic acid in the transmembrane domain and a phophatidylinositol-3 kinase-binding site (YxxM/V) in the cytoplasmic region. Genomic organization reveals that olive flounder DAP10 comprises five exons and four introns. A phylogenetic analysis based on the deduced amino acid sequence grouped the olive flounder DAP10 with other species DAP10. In RT-PCR analysis, DAP10 transcripts were detected predominantly in PBLs, kidney, spleen and intestine.

• Clean Technology
• /
• v.19 no.3
• /
• pp.313-319
• /
• 2013

To produce biodiesel efficiently from fish oil containing 4% free fatty acid, esterification and trans-esterification were carried out with Vietnam catfish oil, which was kindly provided from GS-bio company. Heterogeneous solid acid catalysts such as Amberlyst-15 and Amberlyst BD-20 and sulfuric acid as homogeneous acid catalyst were used for the esterification of free fatty acids in the fish oil. Sulfuric acid showed the highest removal efficiency of free fatty acid and the shortest reaction time among three acid catalysts. The base catalysts for trans-esterification such as KOH, $NaOCH_3$ and NaOH were compared with each other and KOH was determined to be the best transesterification catalyst. Some solid material, which assumed to be saponified product from glycerol and biodiesel, were observed to form in the fish oil biodiesel when using $NaOCH_3$ and NaOH as the transesterification catalyst. The initial acid value of fish oil was proven to have a negative effect on biodiesel conversion. Of the three catalysts, KOH catalyst transesterification was shown to have high content of FAME and the optimal ratio of methanol/oil ratio was identified to be 9:1.

• Korean Journal of Environmental Biology
• /
• v.31 no.4
• /
• pp.486-492
• /
• 2013

Recently, a new disease showing symptoms such as epidermal exfoliation and muscular necrosis occurred in cultured Korean catfish. Although the mortality of fishes was low but the economic damages owing to loss of commercial value were severe. The authors isolated the causative agent from diseased fish and observed pathological changes both in naturally and artificially infected fish. The causative bacteria was identified as Aeromonas veronii. Subsequently we observed the daily death and pathological symptoms of artificially infected fish with Aeromonas veronii. Symptoms of artificially infected fish were similar to those of naturally infected fish and all fish died within 7 days after infection. Histopathological changes on the naturally infected fish revealed severe congestion and necrotic degeneration in the liver, spleen and kidney. Some bacterial aggregates with inflammatory degeneration were observed in the heart, and congestion and fibrosis in the lamina propria of digestive tube were predominant. In artificially infected fish, skin erosion and necrotic degeneration of muscle tissue around injected region were particularly manifested. Degeneration of hepatocytes in liver and hyalic degeneration around ellipsoids in spleen were partially observed. However, there were no predominant signs in digestive tube in artificially infected fish.

• Journal of fish pathology
• /
• v.22 no.3
• /
• pp.343-352
• /
• 2009

Natural-killer-cell-enhancing factor (NKEF) belongs to the newly defined peroxiredoxin (Prx) family. It was originally isolated from human erythroid cells. The black rockfish NKEF cDNA was identified through the expressed sequence tag (EST) analysis of PBLs libraries. The full-length NKEF cDNA was 1433 bp long and contained an open reading frame (ORF) of 594 bp that encoded 198 amino-acid residues. The 5' UTR had a length of 39 bp, and the 3’UTR 800 bp. The deduced amino-acid sequence of the black rockfish had a density 93.4, 92.9, 87.8, 85.8, 84.8, 83.8, 80.3, 79.7, 77.2, and 75.2% that of the pufferfish, olive flounder, channel catfish, zebrafish, chicken, common carp, Myotis lucifugus, cattle, human PrxI, rat PrxI, human NKEF-A, and Xenopus tropicalis, respectively. The NKEF gene was expressed in all the tissues of the black rockfish. The RT-PCR indicated that the NKEF transcripts were predominantly in the spleen and gill, less dominantly in the PBLs, head kidney, trunk kidney, and liver, and least in the intestine and muscles. This is the first report on the existence of the NKEF-A gene in black rockfish.

• Journal of Aquaculture
• /
• v.16 no.1
• /
• pp.51-58
• /
• 2003

The first Indian transgenic fish was generated in 1991 using borrowed constructs from foreign sources. To construct transformation vectors for the indigenous fishes, growth hormone genes of rohu (r-CH), Labeo rohita and catfish, Heteropneustes fossilis were isolated, cloned and sequenced; their fidelity was confirmed in prokaryotic and eukaryotic systems. A vector was constructed with grass carp b-actin promoter driving the expression of r-GH. Rohu eggs are large. fragile and swell 2~3 times. when fertilized. Hence they were amenable only for electroporated sperm-mediated gene transfer. Accordingly, the sperm electroporation technique was standardized to ensure 25% hatchling survival and 37% Presumptive transgenics without suffering any deformity. Southern analysis confirmed genomic integration in 15% of the tested individuals (Ti) belonging to family lines 2 and 3: another 25% of the Juveniles (Te) were also proved transgenic but with the transgene persisting extrachromosomally for longer than 1 to 2 years. perhaps due to the presence of replicon in the vector. Transgenics belonging to different family lines grew 6~8 times faster than the respective controls. Difference in growth trends of Ti and Te within a family line was not significant. In the Ti family 3 remarkable growth acceleration was sustained for a period longer than 36 weeks but in those of family 2, it gradually decreased. All transgenic fishes including the rohu converted the food at a significantly higher efficiency. Barring the transgenic mudloach, all the other transgenic fishes consumed food at significantly reduced rate.

• Journal of Marine Bioscience and Biotechnology
• /
• v.3 no.1
• /
• pp.31-37
• /
• 2008

Off the 1,572 km long coastline of Namibia lies known as the Benguela upwelling system, a very rich source of marine life supporting traditional and modern forms of fishery. Commercial fishing and fish processing is one of the fastest-growing sectors of the Namibian economy in terms of employment, export earnings, and contribution to GDP. The fishing industry has grown to the extent that it is currently Namibia's second biggest export earner of foreign currency after mining (90% of national output is marketed for export). In 2005, Namibia harvested about 552,164 tonnes of fish. The final value of processed products (export value) that year was around US$ 376.0 million. Besides the marine captured fisheries, Namibia also has a small but vibrant aquaculture sector. Inland captured fisheries exist in the north-east and north-west of Namibia where as commercial freshwater aquaculture of tilapia and catfish is also undertaken. The inland fisheries are mainly subsistence based and typically labour intensive, with low catch per unit effort. However the subsistence fisheries from these regions play a significant role in the lives of rural community. The domestic market for marine fish products is extremely limited due to the small size of the population (2 million). The fishing industry is a source of considerable employment for many Namibians. Huge potential to increase production exists in Namibia, unpolluted high quality marine waters, high natural primary productivity of the seawater, availability of inexpensive fish by-products from established fish processing sector for inclusion in wet aqua-feeds and well-established processing, packaging and marketing systems due to the marine capture fisheries that can be adopted for aquaculture purpose.

• Korean Journal of Ichthyology
• /
• v.28 no.3
• /
• pp.175-178
• /
• 2016

The karyotype analysis of Liobagrus somjinensis, an endemic Korean freshwater fish with restricted waters and a new species of torrent catfish was carried out from nine females and eight males of Somjingang River, Sikjeong-dong, Namwon-si, Jeollabuk-do, Korea. The diploid number of chromosomes was 42, and its karyotype was composed of 28 metacentrics and 14 submetacentrics; 84 FN (fundamental number). Polyploidy and sex dimorphism were not observed in the present species. The chromosome number of L. somjinensis was the same as its congeners, but there was a difference in karyotypes.

• Proceedings of the Korean Society of Fisheries Technology Conference
• /
• 2000.05a
• /
• pp.233-234
• /
• 2000

Formalin, 37% formaldehyde, has been employed as a chemical for controlling ectoparasites and aquatic fungi responsible for infectious fish of diseases in hatcheries and culture facilities (Roberts, 1978; Schnick, 1991; Rach et al., 1997). Regarding the commercial usage of formaldehyde in the aquaculture industry, the U.S. Food and Drug Administration (FDA) approved three commercial products as parasiticides in a species-specific manner: Paracide-F and Formalin-F for bluegill, catfish, largemouth bass, salmon, and trout and Parasite-S for all finfish (FDA, 1998). Withdrawal time for these products was legally zero when used as permitted under the regulations. With the increased production of cultured fish in Korea, such as olive Hounder Paralichthys olivaceus and black rockfish Sebastes schlegeli, application of formalin to diseased fish has become more frequent. Moreover, there is still some concern about environmental exposures caused by effluents from fish culture facilities. The purpose of the present study was to evaluate residues in fish resulting from therapeutic usage of formalin in the aquaculture industry and to document the rate of disappearance of formaldehyde in seawater treated with formalin. (omitted)