No abstract

The present study was conducted to assess the effect of oxytetracycline hydrochloride (OTC) in rohu, Labeo rohita, with graded doses viz., 80 (1×), 240 (3×), 400 (5×) and 800 (10×) mg kg −1 fish biomass day −1 respectively through feed. Four hundred and fifty healthy rohu juveniles (20 ± 0.12 g) were fed for 30 days followed by 10 days of withdrawal period. Each 10 days intervals, five fish were randomly sampled for blood, serum and tissue for estimation of growth, non-specific immune parameters, enzymatic activities and retention of OTC in muscle tissue. The results showed that there was no significant difference (p > .05) on growth in the treated fish compared with the control. Respiratory burst activity, myeloperoxidase activity, bacterial haemagglutination and haemolysis activities were enhanced significantly (p < .05) on 10 th and 20 th day in the fish fed with 80 and 240 mg kg −1 biomass day −1 respectively during the feeding trial compared with the control. Lactate dehydrogenase and alkaline phosphatase activity increased significantly (p < .05) in the fish fed with 400 and 800 mg kg −1 biomass day −1 respectively compared with the control. Liquid chromatographymass spectrometry/mass spectrometry study of muscle tissue reveals that OTC was retained in muscle tissue in a dose dependent manner and significantly (p < .05) lowest level (0.44 ± 0.03 ppb) was observed on 40 th day in the treated fish fed with 80 mg kg −1 biomass day −1 . Hence, 80 mg kg −1 fish biomass day −1 of OTC may be adhered in L. rohita for treating the fish through feed with 10 days of withdrawal period.

The use of chemicals, biologicals and veterinary medicinal products (VMPs) helps in healthy and sustainable fish production. Information on the use of these products is essential for assessing farming practices, potential human health and environmental risks. A questionnaire‐based nationwide survey covering aquaculture farms (n = 2936) producing carps, tilapia, pangasius and rainbow trout in freshwater and shrimp in brackishwater estimated the use of 52 different types of inputs which included disinfectants (597 g t−1), probiotics (2.28 kg t−1), environmental modifiers (22.82 kg t−1), nutritional supplements (1.96 kg t−1), natural anti‐infective agents (293 g t−1), herbicide and piscicides (844 g t−1), antibiotics (2 mg PCU−1), antifungal (4 mg PCU−1), and antiparasitic (14 mg PCU−1) agents. The bulk of these inputs was used for soil and water quality improvement and had low environmental and human safety concerns. The multivariate analysis revealed significant variation in the frequency and quantity of compounds use among farm groups. Redundancy analysis revealed a significant association between the number of products used and stocking density. The survey also showed a considerable influence of education and farming experience on the usage pattern of aquaculture inputs. Results of the study indicated greater reliance of farmers on the use of disinfectants for biosecurity, nutritional supplements for enhanced growth and environmental modifiers for maintaining soil and water quality in culture systems. Though there was no use of restricted antibiotics and antiparasitic agents, the development and implementation of standard regulatory guidelines are essential for safe and effective use of inputs for sustainable aquaculture.

This study was conducted to evaluate the effect of dietary emamectin benzoate (EB) levels on immune responses, serum enzyme activities, and retention of EB in muscle tissue to establish the withdrawal period in rohu, Labeo rohita juveniles (avg. wt. 18 ± 0.11  g). To ascertain this, 450 healthy L. rohita juveniles were fed with EB in graded doses viz., at 50 (1x), 125 (2.5x), 250 (5x), and 375 (7.5x) μg kg-1 of fish biomass day-1, respectively, in triplicate for 21 days through a basal feed. Upon completion of 21 days, the same experimental fish were fed with basal feed (without EB) for another 14 days to measure the retention of EB in the muscle tissue. Each 7-day interval, five fish were randomly sampled. The results showed that respiratory burst activity, myeloperoxidase activity, bacterial haemagglutination, and haemolysis activities were improved significantly ( p < 0.05 ) in 1x and 2.5x dose fed group from 7th day onwards until 14th day. Few selected enzyme activities viz., LDH and ALP were found to be significantly ( p < 0.05 ) high in the fish fed with EB at 5x and 7.5x dose compared to 1x. The LC-MS/MS study of the experimental fish discloses that EB was retained in muscle tissue at a dose-dependent manner and significantly ( p < 0.05 ) lowest level ( 0.341 ± 0.03  ppb) was retained in the fish fed with 1x dose of EB. Hence, 1x dose of EB may be adhered to treat L. rohita juveniles through feed with 14 days of withdrawal period.

No abstract