Isolation of a Gram Negative Fish Pathogenfrom Moroccan Rainbow Trout Hatcheryin Winter and its Classical Characterization

Salmonidaquaculture represents one of the most important fish groups in the aquaculture industry (FAO, 2016). However, the success and sustainability of salmonid aquaculture largely depend on disease control. Although Rainbow trout is relatively sensitive to diseases, several bacterial, viral and parasitic diseases have been reported. However, only opportunistic pathogens whose infectivity is expressed by a decline in the fish conditions and of its natural defenses, linked to disturbances of the environment or livestock practices. Livestock is the most favorable context for the development of bacterial pathologies, that's why we have too many bacterial pathogenic species for fish; the most serious infections in our latitudes are Aeromonadaceae, Vibrionaceae, Enterobacteriaceae and Flavobacteriaceae (Noga 1996, Austin and Austin 1999, Woo and Bruno 1999). Moroccan aquaculture has undergone a rapid development and expansion over the last decade, to this end, Rainbow trout (OnchorhyncusMykiss) have been maintained at AinAghbal Fish farm – Azrou-Morocco; for production, livestock and transformation activity and also for commercialization. The most important bacterial freshwater pathogen affecting salmonid livestock in fish farms in Morocco is the cold-water disease as a result of affection by Flavobactriumpsychrophilum bacteria. Our study aimed on approving the presence of this bacterium and to characterize it biochemically, enzymatically and also physiologically.