Florfenicol (FF) is one of the common antimicrobials used to control bacterial disease in shrimp aquaculture. This study aimed to determine the pharmacokinetics (PK) parameters of FF in white leg shrimp plasma, hepatopancreas and muscle as well as its residue depletion in shrimp muscle and the impact on shrimp hepatopancreas histology during and after FF medication. In the PK experiment, shrimp were fed once at 10 mg FF/kg body weight (bw) via oral in-feed administration to determine PK parameters in plasma, hepatopancreas and muscle. The maximum concentration (C_max) of 60.56 μg/L in plasma was observed after 1.77 h (T_max). In muscle, a C_max of 11.76 μg/kg was attained after 0.20 h, while in hepatopancreas, the C_max was higher (386.92 μg/kg) and was rapidly obtained (T_max = 0.19 h). The C_max values in shrimp plasma were below the minimum inhibitory concentration (MIC) against Vibrio parahaemolyticus, known to cause acute hepatopancreatic necrosis disease (AHPND) in shrimp. Therefore, it can be concluded that to ensure the effectiveness of this treatment, the dose should be higher than 10 mg FF/kg bw. FF depletion in white leg shrimp muscle and its histological impact on hepatopancreas were determined after feeding FF-medicated feed once-a-day or twice-a-day for 3 consecutive days with a dose of 10 mg FF/kg bw. The residues in shrimp muscle were rapidly eliminated and fell below the limit of quantification at 24 h after stopping medication. The withdrawal time of FF in shrimp muscle was 27.9 degree-days (2 days at 26.5 °C) according to the maximum residue limit (MRL) of 100 µg/kg set by the European Commission and Korean Ministry and when feeding FF twice-a-day for 3 days. The results from histological analysis showed that there was no negative effect on shrimp hepatopancreas after stopping medication in both once- and twice-a-day treatments.

A high-performance liquid chromatography method coupled to tandem mass spectrometry was validated in order to study the pharmacokinetics of cefotaxime in shrimp hepatopancreases and plasma, as well as its withdrawal time related to a maximum residue limit (MRL) in shrimp muscle. Pharmacokinetics parameters were investigated through oral medication at a single dose of 25 mg/kg shrimp body weight and subsequent hepatopancreas and plasma cefotaxime concentration measurements at 0.5, 1, 2, 4, 8, 12 and 24 h after shrimp were fed with medication. The maximum concentration of cefotaxime was observed after one hour in the hepatopancreas (C_max, 19.45 ± 2.10 mg/kg) and 4 h in plasma (0.184 ± 0.061 mg/L). Based on a minimum inhibitory concentration (MIC) of cefotaxime of 4.13 mg/L against Vibrio parahaemolyticus (known to cause acute hepatopancreatic necrosis disease (AHPND) in white leg shrimp), it was observed that the time during which the hepatopancreas cefotaxime concentration was above the MIC was 23 h. An every 24 h cefotaxime treatment could thus be effective in fighting against this bacterium in shrimp. The withdrawal time of cefotaxime was determined after shrimp were fed with medicated feed once a day and twice a day for three consecutive days. Shrimp muscle was collected on day 1 and day 3 during medication and 1, 3, 7, 14 and 21 days after medication was stopped. Considering an MRL of 50 μg/kg, the withdrawal times were 8.5 degree-days (corresponding to 6.9 h at 29.5 °C) after shrimp were fed with medicated feed once a day for 3 days and 95.5 degree-days (77.7 h at 29.5 °C) after shrimp were fed with medicated feed twice a day for 3 days. Moreover, histological analysis revealed that feeding shrimp with cefotaxime at the given dose in once- or twice-a-day treatments did not negatively impact the shrimp hepatopancreas.

This study aimed to determine appropriate densities for rearing pompano juvenile (Trachinotus blochii) in a recirculating system. Four treatments of stocking density were evaluated including 500, 1.000, 1.500, and 2.000 inds/m3 in triplicate. The experimental system for pompano rearing was designed with 120-L tanks connected to 1 settling tank, 1 filter tank, 1 stone filter tank (contained 250 L of filter volume for each tank). The system was fulfilled with marine water at 30 ‰ of salinity and aerated continuously. Pompano were initially stocked at 0.07 ± 0.03 g/fish of body weight and daily fed using commercial pellet contained 55% of crude protein. After 30 days of rearing, the fish stocked at 1.000 individuals/m3 showed the best results in growth rate (0.060 g/day of DWG and 10.97 %/day of SGR) and was significantly higher than the treatment stocked at 1,500 and 2,000 inds/m3 (p < 0.05), however, no significant difference was observed between 1,000 and 500 treatments (p > 0.05).

Bệnh hoại tử gan tụy cấp tính là một trong những nguyên nhân gây thất thoát sản lượng tôm nuôi hàng năm, dẫn đến gia tăng lượng kháng sinh dùng trong hệ thống nuôi tôm. Để giảm thiểu việc sử dụng kháng sinh trong nuôi tôm, nghiên cứu được thực hiện nhằm đánh giá ảnh hưởng của chế độ cho ăn thức ăn có bổ sung chất chiết lá lựu đến tăng trưởng, thông số miễn dịch và khả năng kháng bệnh hoại tử gan tụy cấp tính ở tôm thẻ chân trắng (Litopenaeus vannamei). Thí nghiệm được thực hiện trong 4 tuần với chế độ bổ sung khác nhau, bao gồm nghiệm thức đối chứng, nghiệm thức bổ sung 1% chất chiết lá lựu và nghiệm thức bổ sung 2% chất chiết lá lựu. Kết quả cho thấy (i) chế độ cho ăn bổ sung chất chiết lá lựu mức 2% giúp gia tăng tốc độ tăng trưởng (p>0,05), và một số chỉ tiêu miễn dịch không đặc hiệu ở tôm thẻ chân trắng (p<0,05); (ii) chế độ cho ăn bổ sung chất chiết lá lựu (2%) giúp tăng tỷ lệ sống của tôm thẻ chân trắng khi cảm nhiễm với Vibrio parahaemolyticus (p<0,05). Kết quả đạt được của nghiên cứu cho thấy tiềm năng ứng dụng của chất chiết lá lựu trong phòng bệnh hoại tử gan tụy cấp trong nuôi tôm thương phẩm.

This study aimed to determine pharmacokinetics (PK) parameters of FF in white leg shrimp plasma, hepatopancreas and muscle as well as its residue depletion in shrimp muscle and hepatopancreas, and the impact on shrimp hepatopancreas histology during and after FF medication. In the PK experiment, shrimp were fed once at 10 mg FF/kg body weight (bw) by oral in-feed administration to determine PK parameters in plasma, hepatopancreas and muscle. The maximum concentration (Cmax) of 60.56 μg/L in plasma was observed after 1.77 h (Tmax). In muscle, a Cmax of 11.76 μg/kg was attained after 0.20 h, while in hepatopancreas, the Cmax was higher (386.92 μg/kg) and was rapidly obtained (Tmax= 0.19 h). Cmax values in shrimp plasma were below the minimum inhibitory concentration (MIC) against Vibrio parahaemolyticus, known to cause acute hepatopancreatic necrosis disease (AHPND) in shrimp. FF depletion in white leg shrimp muscle and its histological impact on hepatopancreas were determined after feeding FF medicated feed once a day or twice a day for 3 consecutive days with a dose of 10 mg FF/kg bw. The residues in shrimp muscle were eliminated rapidly, and were below the limit of quantification at 24 h after stopping medication. The withdrawal time of FF in shrimp muscle was 27.9 degree-days (2 days at 26.5 °C) according to the maximum residue limit (MRL) of 100 µg/kg set by the European Commission and Korean Ministry when feeding FF twice a day for 3 days. The results from histological analysis showed that there was no negative effect on shrimp hepatopancreas after stopping medication.

This study aimed to evaluate the effects of temperature on the growth and survival of mud crab (Scylla paramamosain) larvae in two stages including zoea-1 to megalopa (the first experiment) and megalopa to crablet-1 (the second experiment). Each experiment was conducted in a completely randomized design with four temperature levels (27, 30, 33, and 36℃) in triplicate. Stocking density of 200 ind./L for the first experiment and 4 ind./L for the second experiment. Fiberglass tanks of 500-L (containing 300-L and 250-L of 25‰ water for the first and second experiment, respectively) were used in the experiments. The results showed that S. paramamosain larvae at zoea-3 and zoea-4 died at 33℃ or above, while the highest survival rate of this stage was found at 27℃ (11.5%). The growth and larval stage index during the zoea to megalopa stage were significantly higher in 30℃ (p<0.05) compared to those in the 27℃ treatment. In the second experiment, the survival rates of crablet-1 were highest (72.9%) at 27℃ and lowest (34,7%) at 36℃. The growth rate of crablets at this stage increased with increased temperature. The highest carapace width and weight (3.41 mm and 0.030 g, respectively) were recorded at 36℃. The findings of this study suggested that mud crab larvae should be reared at the temperature range of 27-30℃ to maximize their production.