The crucial need for safe and healthy aquatic animals obligates researchers in aquaculture to investigate alternative and beneficial additives. Medicinal herbals and their extracts are compromised with diverse effects on the performances of aquatic animals. These compounds can affect growth performance and stimulate the immune system when used in fish diet. In addition, the use of medicinal herbs and their extracts can reduce oxidative stress induced by several stressors during fish culture. Correspondingly, aquatic animals could gain increased resistance against infectious pathogens and environmental stressors. Nevertheless, the exact mode of action where these additives can affect aquatic animals’ performances is still not well documented. Understanding the mechanistic role of herbal supplements and their derivatives is a vital tool to develop further the strategies and application of these additives for feasible and sustainable aquaculture. Gene-related studies have clarified the detailed information on the herbal supplements’ mode of action when administered orally in aquafeed. Several review articles have presented the potential roles of medicinal herbs on the performances of aquatic animals. However, this review article discusses the outputs of studies conducted on aquatic animals fed dietary, medicinal herbs, focusing on the gene expression related to growth and immune performances. Furthermore, a particular focus is directed to the expected influence of herbal supplements on the reproduction of aquatic animals.
In this study, the effect of artemisia (Artemisia annua) leaves extract (ALE) on the immune system, growth performance and antioxidant capacity of common carp (Cyprinus carpio) was investigated. Fish with initial weight (90.32 ± 1.12 g) were fed various levels of ALE (0, 0.5, 1 and 1.5 g/kg) for 8 weeks. The results showed that the growth performance (FW, WG, SGR, PER, and LER) in fish fed 1 g/kg ALE was increased significantly (P<0.05) and the feed conversion ratio (FCR) was improved in fish fed 1 and 1.5 g/kg ALE in comparison to the control group (P<0.05). Skin mucus total protein was higher in fish fed diet containing 0.5 g/kg ALE than the other experimental groups (P<0.05), while the lysozyme, immunoglobulin and protease was increased by increasing of ALE in diets. Respiratory burst activity and serum immune parameters were higher in fish fed 0.5 g/kg ALE than the other treatments (P<0.05). Increasing of catalase (CAT) and decreasing of malondialdehyde (MDA) were observed in fish fed ALE, while glutathione peroxidase (GPx) increased only in fish fed 0.5 g/kg ALE. Hence, it can be concluded that ALE has considerable potential as a natural immunostimulant and growth promotor supplement for the common carp’s aquaculture.
Common carp (Cyprinus carpio) is widely reared in the polyculture system in Iran. In recent years, this species has reared in concrete ponds under high culture densities. Various aquaculture practices such as high stocking densities and crowding conditions can stimulate stress responses in cultured fish (Adineh et al., 2019; Xie et al., 2008). The stress response can elevate reactive oxygen species (ROS) and cause oxidative stress, immunosuppression and susceptibility to infectious diseases (Naderi et al., 2019; Tort, 2011). Also, aquaculture is under pressure to decrease the application of antibiotics due to the spread of antibiotic-resistant pathogens and food security problems (Chakraborty & Hancz, 2011). Under these conditions, herbal products have been used as immunostimulants in aquaculture to avoid the careless use of dangerous antibiotics. Herbal products can be used in fish farming as alternatives to vaccines, chemicals and antibiotics to prevent and control diseases in fish (Citarasu, 2010; Galina et al., 2009). Thus, the potential use of herbal products as immunostimulants in aquaculture is a promising novel strategy and further studies are beneficial. Many herbal compounds as natural antioxidants inhibit the production of ROS and scavenge free radicals (Chakraborty &
The effects of dietary Nano selenium (Se) and garlic extract on the performance of grass carp under different stocking densities were examined. Fish (2.10 ± 0.09 g) were stocked into 18 tanks: fish were fed a diet supplemented with 1 mg Nano Se and 1 g garlic kg−1 diet (Diet1) or a diet supplemented with 2 mg Nano Se and 2 g garlic kg−1 diet (Diet2) and reared at low (LD, 24 fish per tank), medium (MD, 48 fish per tank), and high (HD, 96 fish per tank) stocking densities. After 60 days, growth was highest in Diet2‐LD and Diet2‐MD groups and lowest in Diet1‐HD group. Results showed an extreme low or high density induced stress responses. At all densities, serum cortisol and glucose levels were significantly lower and amylase and lipase activities were higher in fish fed diet 2. The protease, catalase, and GPx activities were highest in the Diet2‐MD group. The highest SOD activity was observed in medium‐density groups. The serum malondialdehyde level was lowest in Diet2‐LD and Diet2‐MD groups. Thus, higher dietary levels of Nano Se and garlic are recommended to suppress stress and improve growth, digestive activity, and antioxidant capacity in grass carp. In addition, farming fish at medium density is the most optimal aquaculture practice.
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