Pseudomonad Septicemia or Red Spot Disease - Bacterial Diseases of Fish

Pseudomonad Septicemia or Red Spot Disease

CAUSATIVE AGENT:

Pseudomonas fluorescens, P. anguilliseptica, and P. chlororaphis.

SPECIES AFFECTED:

Milkfish (Chanos chanos), goldfish (Carassius auratus), tilapia (Oreochromisniloticus)

GROSS SIGNS:

The external disease signs of pseudomonad septicaemia are similar to those caused by other gram-negative bacterial pathogen of fish. The disease causes small hemorrhages in the skin around the mouth and opercula and along the ventral or abdominal surfaces. The body surface may ooze blood and slime in severe cases but there is no reddening of the fins and anus.

EFFECTS ON HOST:

Pseudomonas spp. enters the host either through the oral route or through bro-ken or abraded skin and damaged gills. The organism is carried throughout the fish body by the blood stream. The bacteria and their toxin destroy body tis-sues, organs and functions. Dysfunctions of the different body organs may lead to mortality of up to 70%.

DIAGNOSIS:

The organisms can usually be isolated from the kidney and other internal or-gans of affected fish, as well as from the lesion. They grow well on most com-mon laboratory media such as BHIA, TSA and NA. GSP agar or Pseudomonas- Aeromonas Selective Agar is a medium that selectively promotes growth ofAeromonas and Pseudomonas, and inhibits growth of other bacteria.

PREVENTION AND CONTROL:

•               Maintain proper stock management procedures, ensure water quality and reduce stocking density.

•               Transfer in a tank and raise temperature to 26-27°C and maintain for about 2 weeks.