Iranian Journal of Fisheries Sciences
Volume:22 Issue: 5, Sep 2023

To minimize the dependence of pisciculture on imported feed and improve the production of fish through the valorization of local feeds, this study was conducted to evaluate the effects of dietary inclusion of Afrostyrax lepidophyllus fruit powder on the growth and chemical composition of Clarias gariepinus juveniles. The juveniles weighing 13±3.1 g were divided into four treatments in triplicates and fed with diets containing 0 (T0 or control), 2 (T1), 4 (T2), and 6 (T3) g/kg A. lepidophyllus fruit powder for 63 days. The feeding rate was 5% of their body weight. The results showed that adding different levels of A. lepidophyllus fruit powder to the diets improved growth, feed utilization, and carcass quality attributes. The African catfish fed with T3 diet recorded higher final weight (43.44±0.23 g), weight gain (WG, 31.43±0.41 g), feed conversion ratio (FCR, 0.91±0.05), and protein efficiency ratio (PER, 2.67±0.14) than those recorded in the control group (40.20 g final weight, 27.20±0.52 g WG, 1.1±0.05 FCR, and 2.24±0.10 PER). The same trend was observed in the body macro-nutrient retention (32.33±0.58 % crude protein, 25.33±0.58 % lipid, and 23.33±0.58 % ash) compared to the control group (20.67±0.58 % crude protein, 16.00±0.00 % lipid, and 17.33±0.58 % ash). Finally, this study clearly showed that dietary inclusion of A. lepidophyllus fruit powder at 6 g/kg improves growth performance, feed nutrient utilization, and body composition in juvenile C. gariepinus.

This study explores the potential of the probiotics and immunostimulants combination (Vimolert®) to enhance the blood biochemistry profile, histopathology, and immune response of Nile Tilapia against Aeromonas hydrophila infection. A total of 150 Nile tilapia were used and divided into five groups, including a negative control group, a positive control group, and three groups fed with Vimolert®-supplemented diets at different doses for four weeks. After this period, groups 2 to 5 were infected with A. hydrophila. The biochemistry parameters including alanine aminotransferase, Aspartate aminotransferase, alkaline phosphatase, urea, and creatinine significantly increased in the positive control group compared to the treated groups. The total protein and albumin levels were significantly lower in the positive control group than in the treated groups, while the globulin level was higher in the treated groups than in the positive control group. Regarding the immune response, which includes nitroblue tetrazolium and lysozyme activity, it was observed that the groups receiving Vimolert® experienced significant increases in the fourth and sixth weeks compared to the positive control group. The histopathological examination unveiled that the positive control group exhibited pronounced pathological alterations, including degeneration and necrosis in the liver tissue, necrosis, and a reduction in hematopoietic cells in the kidney tissue, as well as edema, degeneration, and necrosis in the muscle tissue. Furthermore, there were infiltrations of mononuclear cells and melanomacrophages between the necrotic muscle fibers. In contrast, the treated group displayed milder to moderately altered tissue conditions. Group 4 had the maximum protection after infection compared to the other treated groups. In conclusion, this study underscores the potential of Vimolert® (a mixture of probiotics and immunostimulants) in improving the immune response and resistance of Nile tilapia against A. hydrophila infection. This finding holds significant promise for enhancing the health status and survival of Nile Tilapia in the aquaculture industry, thereby contributing to the sustainability and productivity of this industry.

The present study reports widespread aquatic mortality during an unprecedented harmful algal blooms (HABs) in Chabahar Bay, the largest bay of the Oman Sea and one of the most important fishing areas of Iran, on 15 and 16 June 2019. This volume of aquatic death stopped fishing and tourist activities in this area for a short time. During this event, the microalgae Karlodinium Cf. veneficum with a density of 6.8 × 104 cells mL−1 was identified as the bloom former species. The toxic dinoflagellate K. veneficum has contributed to the aquatic mortality in many coastal areas of the world by producing karlotoxin. The phytoplankton community was studied in this bloom and 46 species of phytoplankton were identified, including 22 species of diatoms,  dinoflagellates (22),  Cryptophyta (1), and  Chlorophyta (1). This is the first occurrence of HABs associated with the dinoflagellate Karlodinium bloom and the first report of the presence of two toxic and dinoflagellate species, Amphidinium carterae and Ostreopsis ovata associated with the algal bloom in the northern  Oman Sea. Chabahar Bay is considered one of the most important areas of aquatic fishing grounds in the region.  The occurrence of HABs regarding toxic dinoflagellates can be a serious risk to aquaculture activities, human health, and the ecosystem in the area. Water consumption of the residents of Chabahar relies on desalination plants, therefore the bloom of toxic microalgae in the Chabahar bay can disrupt the operation of the desalination plant and pose a potential threat to the water supply in this area.

This study was carried out to evaluate the effect of different cinnamon powder levels in low and high carbohydrate diets on growth performance, liver histological changes, and the liver enzyme activity of rainbow trout (Oncorhynchus mykiss) juveniles. For this purpose, 360 rainbow trout with an average initial weight 16.12±1.33 (means±SD) were fed six diets supplemented with Diet1 (200 g/kg carbohydrate), Diet2 (200 g/kg carbohydrate, 30 g/kg cinnamon), Diet3 (200 g/kg carbohydrate, 50 g/kg cinnamon), Diet4 (300 g/kg carbohydrate), Diet5 (300 g/kg carbohydrate, 30 g/kg cinnamon), and Diet6 (300 g/kg carbohydrate, 50 g/kg cinnamon) for 8 weeks The results showed that fish fed Diet2 (62.64) and Diet3 (63.17) had higher weight gain as compared with treatments without cinnamon (p<0.05). Alanine aminotransferase and alkaline phosphatase were influenced by the experimental diet and the highest values were observed in Diet3 and Diet6 treatments (p<0.05), but the lowest content of aspartate aminotransferase was observed in Diet3 and Diet6 treatments (p<0.05). It is concluded that dietary cinnamon can improve growth performance and liver enzyme activity in fish fed a low-carbohydrate diet rather than a high one.

This study investigated the effects of Urtica dioica (Nettle) on health indices, including total hemocyte count (THC) and differential hemocyte count (DHC), total plasma protein (TPP), and glucose level of hemolymph when the Litopenaeus vannamei was fed with diets containing different hot water extract concentrations of U. dioica (10, 50, and 100 mg kg-1) for 40 days. After 14 days of exposure to Vibrio harveyi, the survival rate was determined. The results showed that the use of U. dioica extract led to a significant increase in the health indices, (THC and DHC). The significant increase (p≤0.05) was observed in the frequency of small and large granular hemocyte, as well as in the biochemical indices, the number of hyaline cells, TPP, and glucose level, particularly at higher concentrations of the extract. After 14 days, the survival rate of the shrimps fed with a diet containing 50 mg kg-1 of U. dioica extract, showed a significant difference from other experimental groups. Overall, the hot water extract of the U. dioica can improve health indicators, THC, TPP, and glucose levels, and also increase the survival rate of the shrimp infected with V. harveyi.

Nanoencapsulation of compounds in nanoliposomes can be used as a protective carrier system for bioactive compounds. Phycobiliproteins (PBPs) were extracted from algae with antioxidant, antimicrobial, anti-cancer, and anti-inflammatory properties during processing and storage under different conditions to produce raw materials for healthy foods. In the present study, phycobiliprotein was extracted from Gracilaria gracilis and the amount of pigments was investigated. Also, the physicochemical properties and thermal stability of nanoliposomes (0%, 0.5%, 1%, and 1.5% w/v chitosan) were evaluated. The nanoliposomes’ particle size and polydispersity index (PDI) were from 336.9 to 577.7 nm and 0.25 to 0.28 with the zeta potential (-10.238 to +30.33 mV), respectively. in nanocarriers. The highest nanoencapsulation efficiency of PBPs (83.98%) was obtained under optimal conditions in nanoliposomes with 1.5% chitosan coating. Evaluation of in-vitro release of PBPs from nanoliposomes showed prolonged release of PBPs by increasing the ratio of chitosan in the wall formulation. Thermal behavior and spectroscopy of the samples confirmed the successful nanoencapsulation of the PBPs in the nanoliposome. The results show the use of lipid nanocarriers containing phycobiliprotein can be considered an effective method to protect it against undesirable chemical, sensory, microbial, and tissue changes in food products.

Researchers have used phytochemicals as sustainable and valuable additives to improve reproduction traits and stimulate the immune system in farm-raised fish species followed by minimizing environmental and public health risks. In this regard, phytochemicals are plant-based bioactive compounds and are known as secondary metabolites. They contain various compounds with a remarkable potential to influence the reproductive performance of aquatic animals. Phytochemicals offer a promising approach to regulate reproductive performance and improve productivity in intensive aquaculture. According to the growing demand for eco-friendly solutions, phytochemicals reduce oxidative stress and enhance disease resistance in different farm-raised fish species. They have various bioactive compounds with unique physiological effects, especially on the reproductive performance of aquatic animals. However, the exact mode of action of these additives on aquatic reproduction traits is not yet well-documented. Overall, phytochemicals can be used as a practical alternative to synthetic additives and have the potential to promote sustainability in different aquaculture sectors around the world based on the availability and affordability of medicinal plants in the region. Polyphenols, flavonoids, isoflavones, anthocyanins, phytoestrogens, terpenoids, carotenoids, limonoids, phytosterols, and glucosinolates are well-known phytochemical molecules with innumerable properties in the host such as antibacterial, antiviral, antioxidant, and anti-inflammatory activities. These compounds are commonly administered orally in aquatic animals. Notably, plant extracts containing bioactive compounds like saponins and flavonoids play a vital role in inducing sexual inversion and fertility disorders. However, the concentration of phenolic compounds varies depending on the herbal genetics (genus, species, cultivar, and genotype), plant extraction methods, environmental conditions, and aquatic animal maturation status. Most studies declared that phytochemicals have a profound effect on fish reproduction due to their various bioactive compounds. They can also induce sexual maturation by interacting with hormone receptors, promote gonadal development by stimulating gonadotropin production, improve sperm quality through antioxidant properties, modulate hormone levels, and support reproductive behavior. However, the effects vary based on fish and plant species, dosage, and exposure duration. Further research is needed to optimize the use of phytochemicals in improving reproductive performance in farmed fish.

Knowledge of the reproductive biology of fish is essential for the local fish population management in marine protected areas. The objective of the present study is to determine the sex ratio, reproductive period, and sexual maturity size classes of the blackchin tilapia (Sarotherodon melanotheron) in the marine protected area of Niamone-Kalounayes, located in Casamance, Senegal. A total of 471 individuals including 305 females and 166 males were sampled from June 2021 to July 2022, using an experimental beach seine (250 m long, 25 mm side mesh). The sex ratio (M: F = 1.0: 1.8) was in favor of females. The size at first sexual maturity (Lm50) was obtained 11.00 cm for males and 11.71 cm for females. The seasonal variation in the gonadosomatic index (GSI) indicates that this population has an extended reproduction period, ranging from March to September, with a clear peak in March, followed by a period of sexual rest (October-December), and a period of maturation of the gonads from January through March. Results of this investigation provided insights for better management practices for this specie.

Our study describes the stock status of Planiliza subviridis (Valenciennies, 1836) by emphasizing on growth pattern, growth parameters (asymptotic length, L∞; asymptotic weight, W∞; growth co-efficient, K; age at zero length, t0), sexual maturity size (Lm), age at sexual maturity (tm), growth performance index (Ø'), life-span (tmax), relative weight (WR), form factor (a3.0), mortality rates ( Z, M and F), exploitation rate (E), maximum sustainable yield (MSY), and relative biomass of P. subviridis from the coastal Shibsa River, Southern Bangladesh. A sum of 317 individuals of P. subviridis ranging from 6.50-19.70 cm total length (TL) was sampled during July 2017 to December 2019. The overall b value indicated isometric growth (b = 3.0) pattern. The estimated L∞, W∞, K, and t0 were 20.79 cm, 93.20 g, 1.02 per year, and 0.015 year, respectively. The Lm was estimated as 11.65 cm in TL and tm was 0.82 year. The tmax was 2.93 year and Ø' was 2.64. Fulton’s condition factor was found most suitable for this species. Further, the average relative weight (WR) indicated that the habitat was in a stable situation. In addition, the Z, M, and F were obtained as 2.23, 1.57, and 0.66 year-1, respectively. Length at maximum yield per recruit (Lopt) was estimated as 13.74 cm. Further, the E (0.30) and MSY, maximum sustainable Yield (0.29) indicated balance harvesting occurred in the coastal Shibsa River. Additionally, the relative numbers of survival, individual growth in weight, and cohort biomass was 24%, 40.0 g, and 100% (9.0 kg) when P. subviridis reached 1.2 years. Consequently, the results of our study will be supportive to implement a proper management strategy in the coastal Shibsa River and adjoining ecosystems of Bangladesh.

This study aims to determine the sexual dimorphism seen in the morphological characters of the commercially important demersal fish species Solea solea from the Aegean Sea coasts of Türkiye according to sex and length groups. We found that there were differences parallel to the growth in morphometric characteristics according to the sexes (♀: 166, ♂: 66 sample size) and the three length groups (190 – 229 mm, 230 – 269 mm, >270 mm). Regarding the specimens examined, it is possible to say that the females have isometric growth, whereas growth in males and combined specimens are considered positive allometric in terms of total length and weight relationship. In the length-length relationship, while females showed allometric growth in the proportional measurements of head region (head length, head height, body height, distance between eyes, lower eye diameter, mandible length) and in the values of caudal peduncle and body height, males continued isometric growth. Considering the length groups, the most prominent morphological difference was seen in body height among the specimens of the 190 – 229 mm length group. Females in this size group have a higher body than those of males and show sexual dimorphism. Our estimates of common sole of Izmir Bay (Aegean Sea) population morphometric features and growth dimorphism potential can be used to design spatial management strategies to morphological modelling techniques.