Journal of the Marine Biological Association of India

Volume 17 Issue 1

The bacterial flora of certain marine fishes and prawns in Cochin waters in relation to their environs.

T. C. Karthiayani and K. M. Iyer

Commercially important fishes like sardines, prawns, lobster and seer fish caught off Cochin, sea water samples gathered from different depths (Surface, middle and bottom) and bottom mud were subjected to bacteriological analysis. Qualitatively the predominant organisms found associated with these marine animals were the gram negative, asporogenous, rod-like bacilli of the genera Pseudomonas, Achromobacter and Vibrio. Sea water and bottom mud samples also showed a predominance of gram negative rods, though with considerable variation in generic composition with depth.

Quantitatively the 'bacterial density' of the sea water increased with depth, the highest aerobic count being shown by bottom mud (2.7 x 104 organisms/gm) and the least by surface water upto 14 metres depth (0-90 organisms/gm). But compared to bottom mud, a 10 to 100 fold increase in the bacterial count was observed on the body of the fishes in general and a higher increase (103to 104 fold) at the gills and the highest (104 to 105 fold) in the guts of sardines have been constantly recorded. The significance of the observation has been discussed in relation to the keeping quality of the fish. In the case of sardine studies extending over a period of one year revealed seasonal variation in the total and luminescent bacterial counts and in the biochemical characteristics.

Date : 30-04-1975