Enhancing farmed striped catfish (Pangasianodon hypophthalmus) robustness through dietary ß-glucan.

ß-glucan is a well-documented feed additive for its potent immunostimulatory properties in many farmed fish species. This study examined how it can also be a promising growth promoter, modulate antioxidant enzyme activities, and act as an anti-stress agent in striped catfish (Pangasianodon hypophthalmus). A 12-week feeding experiment was untaken to determine the effects of dietary ß-glucan supplementation at graded levels (0, 0.5, 1.0, and 1.5 g kg-1). Measured indicators suggest that a dietary inclusion level of 1.5 g kg-1 ß-glucan gave the highest positive responses: weight gain (120.10 g fish-1), survival (98.30%), and lower FCR (1.70) (P<0.05). Whole body proximate analysis had only revealed that crude protein was significantly affected by the dietary inclusion of ß-glucan (P<0.05), with the highest protein content (19.70%) being in fish that were fed with 1.5 g kg-1 ß-glucan. Although other inclusion levels (i.e., 0.5 and 1 g kg-1) of ß-glucan did not enhance body protein content (P>0.05). The assessment of fatty acid composition in muscle, liver, and adipose tissues showed modifications with the inclusion of ß-glucan. Antioxidative-related enzyme activities (inc. catalase, glutathione peroxidase, and superoxide dismutase) that were measured in the liver had higher levels when fed with ß-glucan inclusion diets (P<0.05). Following the feed trial, fish were subjected to crowding stress treatment. It was subsequently found that catfish fed with ß-glucan-based diet groups had lower levels of blood stress-related indicators compared to the control group with no dietary ß-glucan. The use of 1.5 g kg-1 of dietary ß-glucan resulted in the lowest measured levels of cortisol (43.13 ng mL-1) and glucose (50.16 mg dL-1). This study has demonstrated that the dietary inclusion of ß-glucan can have functional benefits beyond the immunological enhancements in striped catfish. Furthermore, its use can increase production levels and mitigate the stress associated with intensive farming practices.

Determination of heavy metals (Pb, Cr, As, Hg, and Cd) into the body organs of selected fish, water, sediment, and soil samples from Head Punjnad and Head Taunsa, Punjab, Pakistan.

The present study was conducted on Head Punjnad (HP) and Head Taunsa (HT) to evaluate the contamination of Pb, Cr, As, Hg, and Cd in water, soil, sediment, fish as a whole and fish organs. Fish, water, soil and sediment samples were collected from different sites of HT and HP on a monthly basis for 8 months. Heavy metals in water, soil, and sediment were determined by a polarized Zeeman atomic absorption spectrophotometer and in fish and fish organs by an atomic absorption spectrophotometer. Contamination of Cd, Hg, and As was significantly (P<0.05) higher in water of HP as compared to HT, while Cr showed a non-significant (P>0.05) difference at HP and HT. Pb was significantly (P<0.05) higher in water of HT as compared to HP. In the case of soil, Cd, Hg, and Pb were higher at HT as compared to HP, while As and Cr were significantly (P<0.05) higher at HP as compared to HT. In sediment, contamination of Cd, Hg, and As were significantly (P<0.05) higher at HP as compared to HT, while the Cr difference was non-significant (P>0.05) but Pb showed a significantly (P<0.05) higher value at HT than HP. Cd accumulation in different fish species was recorded as R. rita ˃O. niloticus ˃C. marulius ˃S. sarwari ˃C. idella ˃C. catla ˃N. notopterus ˃E. vacha ˃L. rohita ˃C. carpio, respectively. Hg as O. niloticus ˃S. sarwari ˃R. rita ˃C. marulius ˃C. catla ˃N. notopterus ˃E. vacha ˃L. rohita ˃C. carpio ˃C. idella, respectively. As as O. niloticus ˃R. rita ˃S. sarwari ˃C. marulius ˃C. catla ˃C. carpio ˃N. notopterus ˃C. idella ˃E. vacha ˃L. rohita, respectively. Cr accumulation recorded as L. rohita ˃C. idella ˃O. niloticus ˃C. marulius ˃E. vacha ˃R. rita ˃C. catla ˃C. carpio ˃S. sarwari ˃N. notopterus, respectively. Pb accumulation in different fish species was recorded as C. idella ˃C. carpio ˃N. notopterus ˃L. rohita ˃O. niloticus ˃C. marulius ˃R. rita ˃S. sarwari ˃E. vacha ˃C. catla, respectively. Cd accumulation in different organs was recorded as kidney ˃liver ˃gills ˃muscle ˃skin ˃scale. Hg accumulation in different organs was recorded as kidney ˃gills ˃liver ˃skin ˃muscle ˃scale. As accumulation in different organs was recorded as kidney ˃liver ˃gills ˃muscle ˃skin ˃scale. Cr accumulation in different organs was recorded as gills ˃ liver ˃skin ˃muscle ˃kidney ˃scale. Pb accumulation in different organs was recorded as gills˃ kidney˃ skin˃ liver˃ muscle˃ scale.

The influence of dietary protein concentration on digestive enzyme activities, growth, and body composition in juvenile bullseye snakehead (Channa marulius).

The bullseye snakehead (Channa marulius) is considered as an affordable and robust freshwater fish for farming in Asia. However, there is limited knowledge on the species' full nutritional requirements to date with extensive gaps in our knowledge and particularly in precision aspects of protein requirements. Therefore, a three-month feeding trial was conducted under semi-intensive farming conditions to determine the protein requirement of bullseye snakehead using test diets containing 40 (P40), 45 (P45), 50 (P50), and 55% (P55) crude protein levels. The growth performance results revealed that the 55% dietary protein group (P55) had the highest final mean weight (14.09 g fish-1), and net weight gain (12.82 g fish-1). When compared to other dietary treatments, the final weight (R2 = 0.921), and weight gain (R2 = 0.913), displayed a linear increasing trend as dietary protein is raised. The lowest FCR was observed in 50% (1.94±0.01) and 55% (1.97±0.01) CP diet groups compared to dietary treatments. Further analysis has shown that the body protein content also significantly increased as dietary protein was raised to 55%. Although, a reverse trend was found in body lipid levels with increasing protein in the diet. The incremental dietary protein also elevated proximal intestinal protease activity but decreased amylase and lipase activity. The overall essential and non-essential amino acids levels of snakehead fillet muscle reflected an increase in dietary protein. Overall, this study has shown that the fish fed a diet with 55% crude protein attained the highest growth performance and nutrient profile of the whole fish when compared to other dietary treatments tested. It would appear we did not obtain the maximum potential for growth under the present experimental conditions due to the upper protein constraint of 55% in the diet. Further quantitative studies are suggested.