**2. Vibrio diseases**

#### **2.1 Bacterial septicemia**

This is one of the severe systemic diseases caused by bacteria, which affects shrimps and exhibits the symptoms such as lethargic, show abnormal swimming behavior, expansion of chromatophores, followed by reddish color change in the pleopods which can be seen in the abdominal musculature. In chronic cases, the gill covers appear flared up and eroded along with the melanized black blisters on the carapace and abdomen. The disease caused by *Vibrio alginolyticus, V. anguillarium or V. parahaemolyticus* and diagnosed based on gross signs like its swimming patterns, Food consumption ratio (FCR) and confirmed by analyzing the isolated pathogen from haemolymph or muscle sample by standard microbiological methods and histopathology. Bacterial septicemia can be prevented by maintaining good water quality and by reducing the organic load by increased water exchange. This can be prevented by giving high protein feed with antibiotics, repeated water exchange might help to decrease the density of disease causing pathogens [4].

#### **2.2 Necrosis (Hepatopancreas, muscle and appendages)**

Inflammation in the cells explores the proteins release from tissues and cells, which reflects on the color change of the animals as like milky white. This disease could be caused due to several unfavorable environmental conditions such as water quality, organic load, malnutrition and wastes producecd from the animals, in chronic cases, melanization of setae, antennae, appendages and muscle can be witnessed. Necrosis is usually caused by *Vibrio spp, Pseudomonas spp, Aeromonas spp* and *Flavobacterium spp* and can be diagnosed based on swimming patterns and other symptoms like white patches in cephalothorax and can be prevented by repeated water exchange and feeding nutrient rich feed. Necrosis is controlled by induced molting by applying 5–10 ppm fermented rice cake (**Figure 1**) [5].

## **3. Brown spot diseases: (Shell disease or rust disease)**

This kind of disease in shrimps showed brown to black enodsed areas on the body surface and appendages, *Aeromonas spp*, and *Flavobacterium spp*., are the crucial causative agents involved in the pathogenisis through chitinolytic activity.

**Figure 1.** *Shrimps affected by Necrosis 1.*

Major symptoms are stooped posture and brown to back spots on the exoskeleton, in extreme conditions it might even lead to necrosis [6]. Brown spot disease can be prevented by reducing organic load in water, with repeated water exchange and by feeding the shrimps with nutritional supplement.
