Bacterial diseases and their Management in chosen marine Ornamental fishes

Pramila, S (2002) Bacterial diseases and their Management in chosen marine Ornamental fishes. PhD thesis, PGPM, Central Marine Fisheries Research Institute.

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Abstract

Observations on the disease occurrence among marine ornamental fish and monitoring of environmental parameters were carried out in the marine aquarium, Vizhinjam Research Centre of C. M. F. R. I. It was noted that the microbial load in the aquarium was not significantly affectEd by any individual hydrological parameters. However, the combined effect of the various parameters influenced the general health of the aquarium rea red fish. Three important factors were derived based on the principal component analysis including water and atmospheric temperature, nitrite. dissolved oxygen and pH, which significantly altered the general water quality. The study indicated that sudden imbalances in nutrient parameters following resetting of aquaria form the major reasons for mass mortality, among all groups of fishes. The bacterial isolates from aquarium fish were identified as Flavobacterium (27%). Vibrio (18%), Pseudomonas (16%). Alcaligenes (16%). Acinetobacter (11 %) and members of Enterobactericeae fami ly (8%) . Serratia marcescens was isolated for the first time, which was frequently involved in ulcerative lesions of fish. This species was found to be highly proteolytic in nature, and in view of the resu lts of preliminary studies, it was selected for invef tigating its ro le in inducing pathogenicity in the experimental host, clown fish (Amphiprion sebae Bleeker). The lethal infective dose of the live cells was found to be equivalent to 1 x1 05 cells per gram of fi sh. The extracellular products (ECPs) of Serratia marcescens were highly toxic for the experimental host. The infective dose of the ECPs was estimated as 2.67 ~g per gram body weight of fish. The heat labile nature of the ECP proteins was established by the in vitro studies. The gelatinase and caseinase activities were reduced on heat treatment at 50°C for 10 minutes. Based on SDS-PAGE studies, it was estimated that major proteins responsible for pathology had their molecular weights ranging from 11 kDa to 100 kDa and that most of the proteins had molecular weights higher than 40 kDa. The antibiotic susceptibility pattern of the important bacterial isolates showed that gentamicin, streptomycin, tetracycline, nalidixic acid and ciprofloxacin were capable of inhibiting rJrowth of more than 90% of the isolates tested. The effectiveness of marine natural compounds, antiseptics and autogenous vaccine in controll ing infection due to Serratia marcescens was also investigated. The extracts of the sponges (Sigmodocea carnosa, Callyspongia and an unidentified species), as well as those of two seaweeds (Graci/aria corticata and Valanopsis pachyderma) had excellent inh ibitory activity. Among antiseptics, formalin , acriflavin and malachite green were effective. The efficacy of immunisation using Serratia marcescens bacterin was proved by the 100% Percentage Relative Protection (PRP) obtained after 351h and 50lh day of administration of bacterin.

Item Type:Thesis (PhD)
Supervisor(s):Lipton, A P
Uncontrolled Keywords:Bacterial diseases; Management; marine Ornamental fishes
Subjects:Fish Biotechnology
Theses
Aquaculture > Ornamental Fishes
Divisions:CMFRI-Cochin > Marine Biotechnology
ID Code:7127
Deposited By:Dr. V Mohan
Deposited On:27 Jan 2011 14:45
Last Modified:21 Jan 2014 12:09

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