Ornamental Fish Diseases And Their Management Measures

CMFRI - Winter School Course Manual on “Recent Advances in Breeding and Larviculture of Marine Finfish and Shellfish”. 30.12.2008 - 19.1.2009

Prevalence, distribution and drug resistance of motile aeromonads in freshwater ornamental fishes

The objective of the present study was to assess the prevalence of various motile aeromonads in freshwater ornamental fishes and to elucidate the antibiogram and beta hemolytic activity among the isolates. A total of 120 ornamental fish samples were screened and analyzed for Aeromonas spp. Motile aeromonads were isolated from 37.5% of the ornamental fish samples. Various species of motile aeromonads such as Aeromonas caviae, Aeromonas hydrophila, Aeromonas jandaei, Aeromonas schubertii, Aeromonas sobria, Aeromonas trota and Aeromonas veronii were detected. All the isolates were sensitive to ceftazidime, chloramphenicol, ciprofloxacin and gentamicin. Multiple antibiotic resistance was observed in 58% of the isolates.

Isolation of a pathogenic strain of Vibrio alginolyticus from necrotic larvae of Macrobrachium rosenbergii (de Man)

Giant freshwater prawn, Macrobrachium rosenbergii (de Man), is an important commercial species with considerable export value, ideal for cultivation under low saline conditions and in freshwater zones (Kurup 1994). However, despite more than a decade of research on its larval production systems, vibriosis still hampers seed production resulting in high mortality rates. Among the different species of vibrios, Vibrio alginolyticus has been isolated frequently from diseased shrimp as the aetiological agent of vibriosis and has been described as a principal pathogen of both penaeids and nonpenaeids (Lightner 1988; Baticados, Cruz-Lacierda, de la Cruz, Duremdez-Fernandez, Gacutan, Lavilla- Pitogo & Lio-Po 1990; Mohney, Lightner & Bell 1994; Lee, Yu, Chen, Yang & Liu 1996). Vibrio fluvialis, V. alginolyticus, V. cholerae non-O1 (Fujioka & Greco 1984), Aeromonas liquifaciens and V. anguillarum (Colorni 1985) have been isolated from the larvae of M. rosenbergii. A profound relationship between the abundance of members of the family Vibrionaceae and larval mortality (Singh 1990) and the predominance of Vibrio in eggs, larvae and post-larvae of M. rosenbergii (Hameed, Rahaman, Alagan & Yoganandhan 2003) was reported. The present paper reports the isolation, characterization, pathogenicity and antibiotic sensitivity of V. alginolyticus associated with M. rosenbergii larvae during an occurrence of severe mass mortality at the ninth larval stage.

Lymphoid organ cell culture system from Penaeus monodon (Fabricius) as a platform for white spot syndrome virus and shrimp immune-related gene expression

Shrimp cell lines are yet to be reported and this restricts the prospects of investigating the associated viral pathogens, especially white spot syndrome virus (WSSV). In this context, development of primary cell cultures from lymphoid organs was standardized. Poly-l-lysine-coated culture vessels enhanced growth of lymphoid cells, while the application of vertebrate growth factors did not, except insulin-like growth factor-1 (IGF-1). Susceptibility of the lymphoid cells to WSSV was confirmed by immunofluoresence assay using monoclonal antibody against the 28 kDa envelope protein of WSSV. Expression of viral and immunerelated genes in WSSV-infected lymphoid cultures could be demonstrated by RT-PCR. This emphasizes the utility of lymphoid primary cell culture as a platform for research in virus–cell interaction, virus morphogenesis, up and downregulation of shrimp immune-related genes, and also for the discovery of novel drugs to combat WSSV in shrimp culture

Studies on the freshwater copepod fish parasites of Kerala

Studies on parasitic copepods from freshwater fishes are still in its infancy. In recent years, there- is a renewed enthusiasm in the study of freshwater fish parasites due to rapidly increasing aquaculture practices. The importance of diseases and their control assumes great significance because of the adverse impact of diseases on fish production and its economy. Copepods are one of the most harmful parasites of freshwater fishes. Reports on the damages caused by copepod parasites from different parts on the world are increasing alarmingly. But the information on parasitic copepods of freshwater fishes in India is quite meagre. Knowledge regarding this group of parasites, their Biology and pathology from Kerala. is lacking. The thesis consists of five chapters. The first chapter is a general introduction which deals with the review of literature on various aspects of parasitic copepods viz; systematics, life history, host-parasite relationship, ecology, pathogenicity, prophylaxis and control measures. Systematics of parasitic copepods of freshwater fishes collected during the present study forms the second chapter. The third chapter deals with the life cycle study of the new Lernaeid copepod, Lernaea osphronemi. The fourth chapter contains host-parasite relationship. ecology and treatment of ‘the’ new species of Lernaea On Osphronemus goramy. General observations and a summary of the entire work constitute the fifth chapter

Virulence Potential And Antibiotic Susceptibility Pattern Of Motile Aeromonads Associated With Freshwater Ornamental Fish Culture Systems: A Possible Threat To public Health

Aeromonas spp. are ubiquitous aquatic organisms, associated with multitude of diseases in several species of animals, including fishes and humans. In the present study, water samples from two ornamental fish culture systems were analyzed for the presence of Aeromonas. Nutrient agar was used for Aeromonas isolation, and colonies (60 No) were identified through biochemical characterization. Seven clusters could be generated based on phenotypic characters, analyzed by the programme NTSYSpc, Version 2.02i, and identified as: Aeromonas caviae (33.3%), A. jandaei (38.3%) and A. veronii biovar sobria (28.3%). The strains isolated produced highly active hydrolytic enzymes, haemolytic activity and slime formation in varying proportions. The isolates were also tested for the enterotoxin genes (act, alt and ast), haemolytic toxins (hlyA and aerA), involved in type 3 secretion system (TTSS: ascV, aexT, aopP, aopO, ascF–ascG, and aopH), and glycerophospholipid-cholesterol acyltransferase (gcat). All isolates were found to be associated with at least one virulent gene. Moreover, they were resistant to frequently used antibiotics for human infections. The study demonstrates the pathogenic potential of Aeromonas, associated with ornamental fish culture systems suggesting the emerging threat to public health