A study on aerobic bacterial flora during incubation of rainbow trout (Oncorhynchus mykiss, walbaum 1792) eggs in hatchery

Abstract

Aerobic bacterial flora in rainbow trout egg, Oncorhynchus mykiss, Walbaum 1792, and the hatchery water were analyzed. It was determined that the number of bacteria varied between $10^ 3-10^ 4$ cfu $g^ {-1}$ in disinfected eggs and $10^ 6-10^ 7$ cfu $g^ {-1}$ in undisinfected eggs. The total bacterial count was 5.7x $10^ 2$ cfu $ml^ {-1}$ in the spring water for the hatchery. The total bacteria counts of outlet water from trough were higher than the inlet water to trough. The bacterial loads of milt and unfertilized egg were also found to be $10^ 3$cfu $g^ {-1}$. In this study, a total of 206 strains were isolated from rainbow trout eggs and hatchery water. Among the bacterial flora of eggs and the hatchery water, comprised of Aeromonas, Coryneforms, Gr (+) Coccus, Enterobactericeae, Acinetobacter, Moraxella, Flavobacterium-Cytophaga constituted groups. The hatchery water was also included Alcaligenes. Aeromonas and Coryneforms were most dominant (38.59 %) and (19.29 %) in eggs respectively. Coryneforms was predominant (26.08 %) in the hatchery water.