• Journal of fish pathology
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• v.27 no.1
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• pp.67-75
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• 2014

Aquaculture drugs have used to prevent disease in aquaculture field for many years. In spite of many advantages, overdose and abuse may cause environmental pollutions and antibiotic resistances. Many countries try to protect the environment, biospecies and food safety. Recently, Korea enact laws and ordinances such as the Aquatic Animal Disease Control Act. The purpose of this act to contribute to the stable production and control system for aquatic diseases. The Maximum residue limits (MRLs) of aquaculture drugs have been established by Ministry of Food and Drug Safety (MFDS) and Drug licensing was in National Fisheries Research and Development Institute (NFRDI) by Aquatic Animal Disease Control Act. There is 750 items in aquaculture drugs and these are classified into 4 group, which is approval, necessary for prescription, unregulated and safety drug, and banned drug. MRLs of 30 items in aquaculture drug have been established by Food Sanitation Act. Future research is required to determine the suitable for abundant varied fishes of drugs for side effects and safety.

• Journal of Food Hygiene and Safety
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• v.33 no.3
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• pp.151-156
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• 2018

The world is becoming overwhelmed with widespread diseases as antibiotic resistance increases at an alarming rate. Hence, there is a demanding need for the discovery and development of new antimicrobial drugs. The ocean is gifted with many organisms like phytoplankton, algae, sponges, cnidarians, bryozoans, mollusk, tunicates and echinoderms, which are known to produce a wide variety of bioactive secondary metabolites with pharmacological properties. Many new therapeutic drugs have emerged from marine invertebrates, although the large algal community is yet to be explored. The bioactivity possessing secondary metabolites of marine algae include polyphenols, phlorotannins, alkaloids, halogenated compounds, sulfated polysaccharides, agar, carrageenan, proteoglycans, alginate, laminaran, rhamnan sulfate, galactosylglycerol, and fucoidan. These metabolites have been found to have great antimicrobial activities against many human aliments. Studies show that the algal community represents about 9% of biomedical compounds obtained from the sea. This review looks at the evolution of drugs from the ocean, with a special emphasis on the antimicrobial activities of marine algae.

• Korean Journal of Food Science and Technology
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• v.42 no.6
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• pp.653-663
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• 2010

This study was conducted to monitor residues of 10 veterinary drugs in food products. Various veterinary drugs were examined including enrofloxacin, ciprofloxacin, norfloxacin, oxolinic acid, amoxicillin, ampicillin, oxytetracycline, tetracycline, chlortetracycline, and doxycycline in beef, pork, egg, chicken, eel, flatfish, and rockfish obtained from 6 different regions (Seoul, Incheon, Daejeon, Gwangju, Daegu, Busan). Residues were detected in 21 (6.5%) samples out of 321 samples. In particular, 2 (1.0%) livestock samples had detected residues among 203 products, and 19 (16.1%) aquaculture samples had residues detected among 118 products. The most frequently detected drug residues in aquaculture products were oxytetracycline and amoxicillin, but the levels were mostly below the MRL (Maximum Residue Limit). In only one flatfish sample, amoxicillin was found at a level higher than the MRL (0.05 mg/kg). In livestock products, residues of most veterinary drugs were not detected. But enrofloxacin was detected in 2 chicken (Korean name: Ogolgae) samples at a higher level than the MRL (0.1 mg/kg as the sum of ciprofloxacin).

• Journal of Aquaculture
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• v.7 no.2
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• pp.123-134
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• 1994

Effects of glucocorticosteroids (GCS) on the thymus and peripheral lymphocytes of Nile tilapia. Oreochromis niloticus were examined. Young fish (5-7g) were injected into intraperitonial cavity with various dose of dexamethasone (DEX) or hydrocortisone (HC). Histology of thymus and thymocyte counts in treated fish were compared to normal ones. The results showed that in vivo adminstration of DEX or HC induced weight loss of thymus and reduction of thymocytes, and both of these were dose and time dependent. In vivo treatment of thymocytes with 10 mM DEX or 10 mM HC for 12hrs caused DNA fragmentation. Both drugs could split the DNA into fragments of about 180-200 base paire multiples. There was no change in granulocytes of peripheral blood due to the treatment of DEX or HC with various length of time. In contrast, treatment of DEX or HC for 2-3 days decresed number of peripheral lymphocytes. The results indicate that the thymocytes and circulating lymphocytes would respond to GCS depending on several factors, such as nature of the hormone, dose, and duration of treatment.

• Journal of fish pathology
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• v.36 no.2
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• pp.403-408
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• 2023

Mullet is an important marine aquaculture fish species in Korea, with a total of 7,237 tons produced as of 2022, making it the 5th most produced marine aquaculture fish species. In this study, ectoparasites presumed to be isopods were discovered in the fins of farmed flathead grey mullet (average weight 550 g), and the characteristics of the parasites were confirmed. The length of the parasite was 5 to 18 mm, and 3 to 7 parasites were infected per fish. To analyze the characteristics of the parasites, molecular biological identification and phylogenetic analysis were performed using the cytochrome c oxidase subunit I (COI) gene, and it was confirmed to be most closely related to Nerocila japonica in the Cymothoidae family. To confirm the parasite control effect, a direct exposure drug sensitivity test was conducted on five types of aquatic drugs and fresh water, trichlorfon was confirmed to be effective.

• Journal of Fisheries and Marine Sciences Education
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• v.29 no.3
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• pp.834-846
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• 2017

Aquaculture practices to ensure greater production, such as high density breeding and excessive feeding, are become stressors that raise the prevalence of diseases. Accordingly, increasingly large volumes of antibiotics are used more frequently each year. Long term use antibiotics can generate resistant bacteria, which interrupt treatments and cause a potential transfer to human bodies. Thus, antibiotic resistance is of importance in public health. Tetracycline (Tc) is one of the typical medicines used in the aquaculture drugs, which has a wide range of application including gram-positive and gram-negative bacteria. In the examination of 153 strains isolated from olive flounder (Paralichthys olivaceus) farms located in Jeju in 2016, it turned out that a total of 84 strains were resistant to Tc or oxytetracycline (OTC). The extent to which the strains are resistant to Tc and OTC was confirmed through MIC test, mostly within the range of 25 to $100{\mu}g/m{\ell}$. Twelve different types of tet genes were detected using single and multiplex PCR in the 84 Tc-resistant strains. The PCR was used to find tet(K), tet(M), tet(O), and tet(S), which are known to exist primarily in gram positive strains. According to the results, - tet(S) is the most dominant gene in 49 strains of Streptococcus parauberis, accounting for 63.2%. And there were two strains that have two different types of resistant genes. The multiplex PCR was used to detect tet(A), tet(B), tet(C), tet(D), tet(E), and tet(G), which are commonly found in gram-negative strains. Each of tet(B), tet(D), and tet(B)&(M) was found in a strain presumed to be Vibrio sp., and only tet(D) was found in 10 Edwardsiella tarda strains.

• Animal cells and systems
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• v.13 no.4
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• pp.429-437
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• 2009

The control mechanism of gonadotropin-releasing hormone (GnRH) on gonadotropin (GTH) release was studied using cultured pituitary cell or cultured whole pituitary obtained from Testosterone (T) treated and control immature rainbow trout. The release of FSH was not changed by salmon type GnRH (sGnRH), chiken-II type (cGnRH-II), GnRH analogue ([des-$Gly^{10}D-Ala^6$] GnRH ethylamide) and GnRH antagonist ([Ac-3, 4-dehydro-$Pro^1$, D-p-F-$Phe^2$, D-$Trp^{3,6}$] GnRH) in cultured pituitary cells of T-treated and control fish. Indeed, FSH release was not also altered by sGnRH in cultured whole pituitary. All tested drugs had no effect on the release of LH in both culture systems of control fish. The levels of LH, in contrast, such as the pituitary content, basal release and responsiveness to GnRH were increased by T administration in both culture systems. In addition, the release of LH in response to sGnRH or cGnRH-II induced in a dose-dependent manner from cultured pituitary cells of T-treated fish, but which is not significantly different between in both GnRH at the concentration examined. Indeed, LH release was also increased by sGnRH in cultured whole pituitary of T-treated fish. GnRH antagonist suppressed the release of LH by sGnRH ($10^{-8}\;M$) and GnRH analogue ($10^{-8}\;M$) stimulation in a dose-dependent manner from cultured pituitary cells of T-treated fish, and which were totally inhibited by $10^{-7}\;M$ GnRH antagonist. These results indicate that the sensitivity of pituitary cells to GnRH is elevated probably through the T treatment, and that GnRH is involved in the regulation of LH release. GnRH-stimulated LH release is inhibited by GnRH antagonist in a dose-dependent manner. The effects of gonadal steroids on FSH levels are less clear.

• Journal of Microbiology and Biotechnology
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• v.32 no.6
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• pp.681-698
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• 2022

The Nile tilapia Oreochromis niloticus, Atlantic salmon Salmo salar, rainbow trout Oncorhynchus mykiss, olive flounder Paralichthys olivaceus, common carp Cyprinus carpio, grass carp Ctenopharyngodon idella and rohu carp Labeo rohita are farmed commercially worldwide. Production of these important finfishes is rapidly expanding, and intensive culture practices can lead to stress in fish, often reducing resistance to infectious diseases. Antibiotics and other drugs are routinely used for the treatment of diseases and sometimes applied preventatively to combat microbial pathogens. This strategy is responsible for the emergence and spread of antimicrobial resistance, mass killing of environmental/beneficial bacteria, and residual effects in humans. As an alternative, the administration of probiotics has gained acceptance for disease control in aquaculture. Probiotics have been found to improve growth, feed utilization, immunological status, disease resistance, and to promote transcriptomic profiles and internal microbial balance of host organisms. The present review discusses the effects of single and multi-strain probiotics on growth, immunity, heamato-biochemical parameters, and disease resistance of the above-mentioned finfishes. The application and outcome of probiotics in the field or open pond system, gaps in existing knowledge, and issues worthy of further research are also highlighted.

• Journal of fish pathology
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• v.32 no.1
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• pp.37-43
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• 2019

Due to the rapid global expansion of aquaculture industry during the past decades, production volume of aquatic organisms has accordingly grown. This has been accompanied by a rise in the incidence of diseases in aquatic organisms, leading to an increased use of aquatic medicines. While aquatic medicines are essential for the prevention and treatment of diseases of aquatic organisms, misuse can cause evolution of antibiotic-resistant bacteria and pose serious problems to the safety and hygiene of fisheries products. In this study, we surveyed and compared, by analyzing data compiled by all national control centers for aquatic animal diseases in South Korea, to estimate the amount of aquatic medicines sold in different regions between 2012 through 2015. Since we also examined the marketing routes of aquatic medicines, this basic data can be utilized for policy implementation to improve drug safety. In the future research, however, it will be clearly necessary to estimate directly the amounts of drugs actually applied to aquaculture organisms. The current sales figure data should be helpful for preparation of an effective system for aquatic drug use management.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.4
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• pp.369-373
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• 1985

The characteristics of a pathogen isolated from infected tilapia, which showed the external symptoms of fin erosion and body deceleration, were examined. The strain of isolated pathogen was identified as Flexibactor columnaris, The normal tilapia dipped into suspensions of the isolated pathogens has developed the infective symptoms. The strain of Flexibactor columnaris was sensitive to kanamycin, tetracycline, and amikacine, but resistant against sulfa drugs. This strain could not grow in the cytophaga media containing over $2\%$ NaCl or over $50\%$ sea water. In cytophaga broth containing more than $50\%$ or sea water instead of distilled water, the number of Flexibacter columnaris decreased from about $10^6/ml\;to\;10^4ml$ within one hour after inoculation. On the other hand, in cytorhaga broth containing more than $5\%$ of NaCl, the number rapidely reached less than 10/ml from about $10^5/ml$ within one hour after inoculation.