Intensification of shrimp farming practices has increased the number and severity of disease outbreaks globally. As a result, diseases have become a significant barrier to profitable and sustainable shrimp production. Shrimp farming practices are reviving in India after its downfall in the late 90s. However, these farming practices also witness disease outbreaks due to viral and bacterial infections. Among the bacterial infections, Vibrios are the most important bacterial causative agents found in shrimp farms. They are ubiquitous and invariably seen in shrimp production conditions as opportunistic pathogens. The present study was conducted to identify the bacterial pathogens associated with the shrimp Penaeus vannamei farming systems along the Ratnagiri coast. In all, two farming units were selected: Varavade farm - a six-year-old farm, and Chinchkhari farm, a new virgin farm. The water and sediment samples were collected from January to May 2022 throughout culture period of one crop. The total plate count (TPC) of the shrimp farm water samples of the Varavade farm varied from 4.35 to 6.32 log10 CFU mL-1. In the sediments, the minimum value of TPC was 4.99 log10 CFU g-1, while the maximum value observed was 7.25 log10 CFU g-1. The Total Vibrio count (TVC) of water samples from Varavade farm varied from 4.01 to 5.63 log10 CFU mL-1. In the sediments, the minimum value of TVC was 4.64, while the maximum value observed was 6.56 log10 CFU g-1. The statistical analysis showed a significant difference in TPC and TVC (p < 0.05) among different days of culture. The TPC of the shrimp farm water samples of the Chinchkhari farm varied from 5.22 to 8.17 log10 CFU mL-1. In the sediment, the minimum value of TPC was 5.87, while the maximum value was observed at 8.45 log10 CFU g-1. The TVC of water samples from the Chinchkhari farm varied from 4.75 to 6.89 log10 CFU mL-1. In the sediment, the minimum value of TVC was 5.16, while the maximum value observed was 6.70 log10 CFU g-1. The statistical analysis showed a significant difference in TPC and TVC (p < 0.05) among different days of culture. The bacterial load was observed to increase with the progression of the culture period on both farms. The usage of probiotics, chemicals, and water exchange was observed to promote a decrease in the bacterial community.
The present study was carried out to evaluate the growth and survival of pearlspot, Etroplus suratensis (Bloch, 1790) fry using practical diets incorporated with different levels of mosquito fern, for 60 days. The fry with average length and weight of 25±0.1 mm and 0.54±0.03 g, respectively were reared at stocking density 15 fry/100 L in brackishwater. Four iso-nitrogenous (30% crude protein) and iso-calorific diets were formulated with incorporation of 0, 10, 20 and 30% powdered fermented azolla. Fry were fed at the rate of 7-8% body weight per day. The highest growth parameters and survival were recorded for control diet. However, the fry fed 10% azolla incorporated diet showed similarities in weight gain %, specific growth rate and feed conversion ratio with control group.
Intensification of shrimp farming practices has resulted in an increase in the number and severity of disease outbreaks globally. As a result, diseases have become a significant barrier to profitable and sustainable shrimp production. Shrimp farming practices are reviving in India after its downfall in the late 90s. However, these farming practices also witness disease outbreaks due to viral and bacterial infections. Among the bacterial infections, Vibrios are the most important bacterial causative agents found in shrimp farms. They are ubiquitous in nature and invariably seen in shrimp production conditions as opportunistic pathogens. The present study was conducted to identify the bacterial pathogens associated with the shrimp Litopenaeus vannamei farming systems along the Ratnagiri coast. In all, two farming units were selected; Varavade farm - six year old farm and Chinchkhari farm was new virgin farm. Between January and May of 2022, samples of the water and sediment were taken. The total plate count (TPC) of the shrimp farm water samples of the Varavade farm varied from 4.35 to 6.32 log10 CFU mL-1. In the sediments, minimum value of TPC was 4.99 log10 CFU g-1 while the maximum value observed was 7.25 log10 CFU g-1. The Total Vibrio count (TVC) of water samples from Varavade farm varied from 4.01 to 5.63 log10 CFU mL-1. In the sediments, minimum value of TVC was 4.64 while the maximum value observed was 6.56 log10 CFU g-1. The statistical analysis showed that there was a significant difference in TPC and TVC (p<0.05) among different days of culture.Total plate count (TPC) of the shrimp farm water samples of the Chinchkhari farm varied from 5.22 to 8.17 log10 CFU mL-1. In the sediment, minimum value of TPC was 5.87 while the maximum value was observed 8.45 log10 CFU g-1. The Total Vibrio count (TVC) of water samples from Chinchkhari farm varied from 4.75 to 6.89 log10 CFU mL-1. In the sediment, minimum value of TVC was 5.16 while the maximum value observed was to 6.70 log10 CFU g-1. The statistical analysis showed that there was a significant difference in TPC and TVC (p<0.05) among different days of culture. The bacterial load was observed to be increased with the progression of the culture period in both farms. The usage of probiotics, chemicals and water exchange was observed to be helping in the decrease of the bacterial community.
An experiment was conducted to study the effect of different levels of water hardness on survival and growth of two size groups (group A: 2.00 ± 0.20 cm and group B: 2.50 ± 0.20 cm) of fry of angelfish (Pterophyllum scalare). The gain in length was 1.9 ± 0.02 cm and 3.20 ± 0.04 cm in group A and B respectively in 100 mg l-1 CaCO3 hardness, which was superior among all the treatments. Survival was 100% in all treatments, but specific growth rate differed significantly within both the groups. The specific growth rate was 1.87 ± 0.07 and 2.81 ± 0.33 in group A and B, respectively in 100 mg l-1 CaCO3 hardness, which was significantly (P 0.05) in both the size groups. Among treatments, the best growth results were obtained at 100 mg l-1 CaCO3 hardness. Growth was significantly suppressed at 200 and 300 mg l-1 CaCO3 hardness in both the size groups. The results indicated that 100 mg l-1 CaCO3 is the optimum level for growth and survival of angelfish fry.
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