一種淡水魚（草魚）疾病的研究

An investigation of a disease of the fresh water fish Ctenopharyngodon idellus and its chemotherapeutical control

Fourteen species of bacteria were isolated from diseased grass-carps, Ctenopharyngodon idellus. Afer identification and inoculation tests, one of these bacteria (A-2), Aeromonas punctata Zimmermann, was found to be a pathogen for the grass carp. Aeromonas punctata is a gram negative, rod-shaped bacteria, motile by means of a single polar flagellum. It is able to digest gelatin, casein and starch, and gives positive reactions for catalase, indole, hydrogen sulfide, methyl red and acetylmethylcarbinol tests. It ferments most carbohydrates with the production of acid and gas. Aeromonas punctata is sensitive to many kinds of antibiotics and sulfonamides, but chloramphenicol was found to be the most efficient antibiotic in controlling this pathogen.