Search

There has been a consistent interest in the aquaculture industry in the use of plant elements as a substitute for fish meal (FM). The present study aimed to examine the impact of substituting FM with varying proportions of fermented spent coffee grounds (FCG) on the growth performance, feed stability, blood biochemistry, liver, and intestinal histology of African catfish, Clarias gariepinus. Five isonitrogenous diets were formulated with a crude protein content of 32 %. These diets were created with different percentages of FM replacement, specifically 0 % (T1), 10 % (T2), 20 % (T3), 40 % (T4), and 80 % (T5). The fish were then fed these diets for a duration of 70 days. The results showed that fish provided with 10 % FCG (T2) gave the highest improvement (p < 0.05) in growth conditions compared with other treatments. The feed’s physical properties were varying, but floatability and water stability were highest in T2 diets. Total bacteria (TB) in feed and intestine were more elevated in fish fed with 10 % FCG compared to other treatments. The histopathological damage in the intestine and liver morphology was observed when the level of inclusion of FCG was increased in all treatments. In addition, T2 gave the highest value (p < 0.05) in villus length, width, and crypt depth. Some parameters were improved in both blood haematology and blood biochemical parameters, and T2 gave the highest value (p < 0.05) in white blood cells, lymphocytosis, monocytes, red blood cells, haemoglobin, albumin, globulin, total protein, and creatine. In summary, the substitution of 10 % FCG with FM holds potential for application within the aquafeed sector, as it has been observed to contribute to enhanced growth and improved health conditions in African catfish and other freshwater species.

Application of dietary feed additives is an excellent approach to improve fish health status under different stressful condition. The current study investigated the roles of different level of dietary gallic acid (GA) on growth performances, biochemical indices, digestive enzymes activity, antioxidant status and immunological responses in common carp (Cyprinus carpio) subjected to crowding stress. Fish were fed with the control diet (0 mg/kg GA) and four graded levels of GA (150, 300, 450 and 600 mg/kg) for 60 days each with three replicates. Moreover, fish were challenged with crowding stress for six hours. The results revealed significant improvement in growth performances, immune indices in common carp fed with dietary GA in comparison to the control diet. The study also demonstrated significant improvement feed utility through enhanced activities of digestive enzymes (amylase, lipase and protease) by dietary GA provision. Moreover, dietary GA noticeably enhanced the antioxidant status of common carp by improving superoxide dismutase, catalase, glutathione peroxidase, and lowering malondiadehyde specially after exposure to crowding stress. Considering these results, the current study reveals that dietary GA at the concentration of 450 mg/kg can successfully improve growth performances, biochemical indices, digestive enzymes activity, antioxidant status and immunological responses in common carp.

Heavy metals pollution causes a threat to the aquatic environment and to its inhabitants when their concentrations exceed safe limits. Heavy metals cause toxicity in fish due to their non-biodegradable properties and their long persistence in the environment. This review investigated the effects of heavy metals on early development, growth and reproduction of fish. Fish embryos/larvae and each developmental stage of embryo respond differently to the intoxication and vary from species to species, types of metals and their mode of actions, concentration of heavy metals and their exposure time. Many of the heavy metals are considered as essential nutrient elements that positively improve the growth and feed utilization of fishes but upon crossing the maximum tolerable limit these metals cause not only a hazard to fish health but also to human consumers and the disruption of ecological systems. Reduced gonadosomatic index (GSI), fecundity, hatching rate, fertilization success, abnormal shape of reproductive organs, and finally failure of reproduction in fish have been attributed to heavy metal toxicity. In summary, this review sheds light on the manipulation of fish physiology by heavy metals and seeks to raise sensitivity to the prevention and control of aquatic environmental contamination, particularly from heavy metals.

Probiotics, an eco-friendly alternative to antibiotics application appears to have strong potential for improving the sustainability of aquaculture. The aim of the study was to evaluate the effect of probiotic brewer’s yeast, Saccharomyces cerevisiae supplementation on growth performance, feed utilization and intestinal morphometry of Nile tilapia, Oreochromis niloticus. A feeding trial of 60 days was conducted in which tilapia fingerlings (7.55 ± 1.25 g) were randomly distributed into three replicate aquaria under four different treatment groups, receiving S. cerevisiae at 0, 1, 2 and 4 g kg−1 diet, respectively. At the end of the feeding trial, growth performance parameters (weight gain, WG; % WG; specific growth rate, SGR), feed utilization indices (protein efficiency ratio, PER; feed conversion ratio, FCR) and intestinal morphology were assessed. The results obtained from this study revealed that growth performance and feed utilization indices were increased significantly in the fish fed with 4 g kg−1 S. cerevisiae supplemented diet compared to controls. The length, width and area of villus were significantly enlarged in fish fed 4 g kg−1 S. cerevisiae supplemented diet. Likewise, intestinal mucosal fold, width of lamina propria, width of enterocytes and number of goblet cells increased in the fish fed with 4 g kg−1 S. cerevisiae supplemented diet. These results demonstrated that S. cerevisiae can be effectively recommended as an important growth promoter for tilapia culture.

Chromium is considered the most detrimental pollutant to the aquatic organisms. The present experiment was conducted to determine the acute toxicity of chromium in view of its effects on hemato-biochemical parameters and the structure of erythrocytes in striped catfish, Pangasianodon hypophthalmus. Fish were exposed to seven different concentrations (0, 10, 20, 30, 40, 50 and 60 mg/L) of chromium, each with three replications for 96 h. After 96 h of exposure, the survived fish were sacrificed to measure hemato-biochemical parameters (hemoglobin, Hb; red blood cell, RBC; white blood cell, WBC; packed cell volume, PCV; mean corpuscular volume, MCV; the mean corpuscular hemoglobin, MCH and blood glucose). In addition, erythrocytic cellular abnormalities (ECA) and erythrocytic nuclear abnormalities (ENA) of peripheral erythrocytes were assayed. No mortality was observed up to 10 mg/L, but 90% and 100% mortality was observed at 50 mg/L and 60 mg/L, respectively after a 96 h exposure period. The 96 h LC50 value through probit analysis was 32.47 mg/L. Hb (%), RBC (×106/mm3) and PCV (%) significantly decreased at 20, 30 and 40 mg/L of chromium, whereas WBC (×103/mm3), MCV (μm3) and MCH (pg) showed the opposite scenario. Blood glucose (mg/dL) levels significantly increased at 10, 20, 30 and 40 mg/L of chromium compared to 0 mg/L. Frequencies of ECA and ENA significantly increased with increasing chromium concentrations. This study indicates that chromium is highly toxic to striped catfish.

The analytical experiment was executed to present detailed reports on the concentration of heavy metals (nickel, iron, zinc, manganese, chromium, lead, and cadmium) in farmed shrimp, Penaeus monodon and its concomitant human health risks upon consumption. A total of 147 farms from six sub-districts of Khulna were selected for sample collection and concentration of heavy metals were determined by Atomic Absorption Spectrometry (AAS) method, following electro-thermal heater digestion. Ni and Cr were found considerably below the detectable limit (BDL) in four sub-districts, while Cr found in shrimps from Rupsa and Paikgacha were far higher than the maximum recommended limit defined by FAO and WHO. The average concentrations of Fe and Mn in all sub-districts crossed the recommendations, whereas average concentrations of Zn, Ni, Cd, and Pb were within the recommendations. Regardless of sampling site, target hazard quotients (THQ) of more than 1 contributed by Fe confirmed higher level of hazard index (HI), indicating potential human health risk. Fortunately, no heavy metal or their additive effect found to offer lifetime potency of carcinogenesis upon consumption of these shrimps. Therefore, probabilistic non-carcinogenic human health risk from Fe contamination necessitates stringent monitoring and controlling of this metal from different sources to farms.

The study was carried out to obtain information on the present status and trend of finfish diversity of the Old Brahmaputra river, Bangladesh. Samples were collected directly from a professional fishing boat caught by different nets, traps and hooks from January 2019 to December 2019. Together with 4 exotic species, a total of 49 species under 6 families were recorded. Though a biodiversity index of 3.65854 and a dominance index of 0.030929 represent the richness of ichthyo-diversity within the river, Synbranchiformes and Tetraodontiformes were not reported throughout the study period. Linear regression analysis showed a positive correlation between water height of the river and monthly abundance of the species found. Catch composition of catfishes and snakeheads slumped while barbs showed triumph over previous findings. A majority of fish recorded were within the least concern category according to IUCN (2015) but portions also belonged to critically endangered, endangered, and vulnerable categories as well. Therefore, conservation measures must be infixed in the Old Brahmaputra river to hold the fish diversity in a sustainable state.