Limnoecology and carp fish species peak spawning timing in haor basin of Bangladesh

The present study was conducted to investigate the peak spawning timing based on the reproductive performance of carps species related to limnoecology variables, emphasizing to assess within fish population breeding variability and monthly effects over a period from April to July 2016 in the haors basin of Bangladesh. The reproductive performances were evaluated through artificial breeding technique by hormone injection in matured brood fish. The reproductive performance in terms of mean fecundity, egg weight, fertilization, hatchling and larval survival were significantly (P<0.05) highest in the month of May to June, and April compared to the months of spawning timing for the three Indian major carps, and the three exotic carp respectively. The ovulation and hatching time were significantly (p<0.05) highest in the month of July and April for the Labeo rohita, in the month of Aril for Catla catla and Cirrhinus cirrhosus and for the three exotic carp in the month of June to July compared with the others months of the breeding season. However, total length, weight and spawning response were not significantly (P>0.05) different among the months of the breeding time for the six carp species and a trend similar to the spawning success was also observed and numerically the mean value of the spawning response rate was between 88 to 93% and 83 to 90% for the three Indian major carps and the three exotic carp respectively among the months of the study. Furthermore, mean monthly values of limnoecological variables such as temperature, pH, and dissolved oxygen were not significantly (P>0.05) different among the months of the breeding season of the carp species in the three haor study sites. This study may serve as an update on carp fish species peak spawning timing related to limnoecological variables in the haor basin for carps species broodstock sustainable management to get quality seeds in the aquaculture hatchery industry

Effect of Different Dietary Lipid Levels on Spawning Performance and Egg Quality of Pangasianodon hypophthalmus (Sauvage, 1878)

Dietary lipid manipulation of broodstock diet offers a strategy for improving spawning performance and egg quality of broodstock fish. Although many studies were conducted on basic nutrient requirements for fingerlings and juveniles of Pangasianodon hypophthalmus (Sauvage, 1878); the artificial feed for P. hypophthalmus broodstock is still lacking. This study analysed the effect of different levels of lipid in the diet on spawning performance and egg quality of female P. hypophthalmus broodstock. Three test diets were formulated containing 1:1 ratio of palm oil and fish oil blends at the level of 60, 90 and 120 g.kg-1 with a constant 300 g.kg-1 protein and fed to triplicate groups of female broodstock for 150 days at the rate of 20 g.kg-1 body weight twice daily. The ovary weight, gonadosomatic index, fecundity, egg weight and diameter and egg fertilisation rate were significantly (P < 0.05) increased for fish fed with 90 and 120 g.kg-1 lipid diet compared to 60 g.kg-1 lipid diet. However, there was no significant difference between fish fed with 90 and 120 g.kg-1 lipid diet; thus an increase in dietary lipid above 90 g.kg-1 would not make any significant contribution. The increased performance of female broodstock fed with higher dietary lipid and fish oil at the ratio of 1:1 for crude palm oil and fish oil up to 90 g.kg-1 contributed in the enhancement of the reproductive performance and egg quality of P. hypophthalmus

A replacement of plant protein sources as an alternative of fish meal ingredient for African catfish, Clarias gariepinus: A review

Aquaculture is one of the fastest growing industries in the world. This industry supplies half of the fisheries products consumed annually, and future global demand can only be supplied by increasing aquaculture production, which, in turn, requires more aquafeed. Alternative ingredients must be increasingly used to supply significant proportions of protein and energy in aquafeeds, creating both challenges and opportunities for researchers and industry. Nowadays, there are too many researches on fish disease, growth and health but less in a fish feed especially a replacement of protein from plant sources in the fish feed. One of the alternative ways to optimise the growth and health condition of the fish is provide them a good protein from plant as a replacement in fish meal with the natural source protein instead of giving a good rearing condition and caring of the fish. The present article was constructed to highlight a replacement of plant protein sources as an alternative of fish meal for fish feed in African catfish, Clarias gariepinus that has been done by researchers. However, the application of replacement from plant protein sources in fish meal is now gradually gaining importance in commercial aquaculture practices and opened the door for the researchers to expend of this application, thus more detailed studies on molecular basis should be looked as to get the quality and enough nutrient fish feed for good production of aquaculture industry

Exploring the roles of phytobiotics in relieving the impacts of Edwardsiella tarda infection on fish: a mini-review

Edwardsiellosis caused by Edwardsiella tarda resulted in significant economic losses in aquaculture operations worldwide. This disease could infect a wide range of hosts, including freshwater, brackish water, and marine aquatic animals. Currently, antibiotics and vaccines are being used as prophylactic agents to overcome Edwardsiellosis in aquaculture. However, application of antibiotics has led to antibiotic resistance among pathogenic bacteria, and the antibiotic residues pose a threat to public health. Meanwhile, the use of vaccines to combat Edwardsiellosis requires intensive labor work and high costs. Thus, phytobiotics were attempted to be used as antimicrobial agents to minimize the impact of Edwardsiellosis in aquaculture. These phytobiotics may also provide farmers with new options to manage aquaculture species' health. The impact of Edwardsiellosis in aquaculture worldwide was elaborated on and highlighted in this review study, as well as the recent application of phytobiotics in aquaculture and the status of vaccines to combat Edwardsiellosis. This review also focuses on the potential of phytobiotics in improving aquatic animal growth performance, enhancing immune system function, and stimulating disease resistance

The roles of soybean lecithin in aquafeed: a crucial need and update

Soybean lecithin is extensively used as the dietary supplementation of phospholipids in animal production. Soybean lecithin plays significant roles in aquafeed as growth promoter, feed enhancer, immunity modulator and antioxidant activity stimulator for aquaculture species. Besides, soybean lecithin is also reported to help aquaculture species being resilient to physical and chemical stressors. In this review, common sources, chemical structure and mode of action of lecithin, with highlight on soybean lecithin application in aquaculture over four-decadal studies published between 1983 and 2023, were evaluated and summarized. By far, soybean lecithin is best-known for its beneficial effects, availability yet cost-effective for aquafeed formulation. Findings from this review also demonstrate that although nutritional profile of long-chain polyunsaturated fatty acids and phosphatidylcholine from egg yolk and marine sources are superior to those from plant sources such as soybean, it is rather costly for sustainable application in aquafeed formulation. Moreover, commercially available products that incorporate soybean lecithin with other feed additives are promising to boost aquaculture production. Overall, effects of soybean lecithin supplementation are well-recognized on larval and juvenile of aquaculture species which having limited ability to biosynthesis phospholipids de novo, and correspondingly attribute to phospholipid, a primary component of soybean lecithin, that is essential for rapid growth during early stages development. In addition, soybean lecithin supplementation plays a distinguish role in stimulating maturation of gonadal development in the adults, especially for crustaceans

Firm-level political risk and equity issuance

We examine whether firm-level political risk influences the issuance of equity (debt) to finance corporate investment. With a sample of 64,693 firm-quarter observations from 2002–2020, we find that firm-level political risk is significantly and positively associated with subsequent equity issuance as opposed to debt issuance. To mitigate endogeneity, we estimate firm fixed-effects regression, perform nearest-neighbor score matching technique and Heckman’s (1979) two-step correction procedure, and employ gubernatorial elections in different states of the U.S. as a shock to the firm-level political risk. We also test for two potential economic mechanisms, financial flexibility and information asymmetry, and find that our baseline results are more pronounced for these channels. Our study presents new evidence on firms’ financing choices in the presence of firm-level political risk

Effect of fish meal substitution with fermented soy pulp on growth performance, digestive enzyme, amino acid profile, and immune-related gene expression of African catfish (Clarias gariepinus)

Fermented soy pulp (FSP) is currently capturing attention worldwide because of the high price of fish meal and its inconsistent supply in recent years. FSP replaces fish meal as a source of protein and energy towards improved fish health and growth. The protein replacement was employed in this study to assess the growth and health status, digestive enzyme, amino acid profile, and immune-related gene expression of African catfish, Clarias gariepinus. The duration of the feeding experiment was 70 days. Five isonitrogenous. (32% crude protein) diets were prepared with FSP replacing D1 (0% FSP), D2 (25% FSP), D3 (50% FSP), D4 (75% FSP) and D5 (100% FSP) to FM component of the diets. D1 diet with 0% FSP was considered as a control. The fermentation process of FSP was carried out for three weeks. This resulted in the experimental diets having significantly different (p \u3c 0.05) growth parameters. The D3 diet showed the highest weight gain and SGR with a mean and standard deviation of 1552.41 ± 81.67% and 1.73 ± 0.03%, respectively. D3 diet had better relative protein digestibility (RPD) value of 92.33 ± 2.19 compared with fish fed with the control diet. Amylase and lipase activities were found to be significantly higher in the D3 diet. The muscle amino acid profiles (arginine, isoleucine, histidine, and leucine) and gene expression (TGF-β1, lyzg, NF-kβ, and hsp90a) were significantly highest (p \u3c 0.05) in the D3 diet. Fresh insights have been demonstrated by the findings of the study into the production of FSP as a replacement product. These insights would efficiently enhance the generation of aquafeed, which are low in cost and healthy towards the production of African catfish and other freshwater species. In conclusion, a new theory on using FSP as a plant-based replacement material and a protein replacement for fish growth and health status booster may be achieved at 50% of FSP inclusion

Alleviation of Salt-Inhibited Germination and Seedling Growth of Kidney Bean by Seed Priming and Exogenous Application of Salicylic Acid (SA) and Hydrogen Peroxide (H2O2)

Salinity is a dominant obstacle to the proper germination of seeds, growth of seedlings, and, consequently, the production of crops. The priming of seeds with different treating agents can efficiently impart salinity tolerance. Kidney bean is a nutritious and popular vegetable crop in the world. Literature shows that salt stress negatively disturbs the germination and growth of kidney beans. In the present research, we investigated the potentiality of salicylic acid (SA) and hydrogen peroxide (H2O2) as priming and exogenous agents to alleviate the salinity-inhibited germination and growth of kidney beans. The seeds were pretreated with SA (1 mM and 2 mM) and H2O2 (0.1 mM and 0.15 mM) and soaked in normal tap water (hydro-priming) for 60 min. In addition, for the control experiment, untreated seeds were used. Finally, primed seeds were subjected to salt stress (150 mM NaCl). Our results exhibited that salt stress considerably lowered the percentage of germination (GP), germination index (GI), seed vigor index (SVI), shoot length (SL), root length (RL), shoot&ndash;root fresh and dry biomass, and plant growth. The results also exhibited that salt stress significantly decreased the relative water content (RWC) and photosynthetic pigments such as chlorophyll, carotenoids, lycopene, and beta-carotene contents. The SA- and H2O2- and hydro-priming stimulated the GP, GI, SL, RL, SVI, and seedling growth. Data also revealed that the supplementation of SA and H2O2 enhanced RWC and photosynthetic pigments. When compared to other treatments, pretreatment with 1 mM SA was determined to be comparatively more effective at imparting the salt tolerance of kidney beans. Overall, these results, via a heatmap and principal component analysis, uncovered that priming and exogenous applications of SA and H2O2 can improve salt tolerance and enhance germination and seedling characteristics of kidney beans

Fermented Soybean Meal (FSBM) in African Catfish (<i>Clarias gariepinus</i>) Diets: Effects on Growth Performance, Fish Gut Microbiota Analysis, Blood Haematology, and Liver Morphology

The study revealed the potential of fermented soybean meal (FSBM) as a fish meal (FM) replacement in African catfish (Clarias gariepinus) feed formulation. Five isonitrogenous diets (32% crude protein) were prepared with five different levels of FSBM as FM replacement, namely 0% FSBM (T1), 40% FSBM (T2), 50% FSBM (T3), 60% FSBM (T4), and 70% (T5). The experimental fish was given the formulated diet for eight consecutive weeks. At the end of the feeding trial, the fish were subjected to growth performance, blood parameters, blood chemical, liver histology, and gut microbiota assessment. The study findings demonstrated that the experimental fish that received the T2 diet exhibited significantly higher (p p p p Akkermansia muciniphila in the experimental fish that received the T2 diet. The gut microbiota indicates that the experimental fish is in a healthy condition. In conclusion, replacing 40% FSBM with FM in aquafeed could enhance C. gariepinus growth performance and health conditions

Comparative study of ovarian development in wild and captive-reared long-whiskered Sperata aor (Hamilton, 1822)

Abstract Long-whiskered catfish Sperata aor is a freshwater catfish known for its supreme flesh quality and fast growth, whose captive-reared broodstock denotes a difficult challenge for aquaculture. The reproductive dysfunctions in long-whiskered catfish raised in tank conditions were observed by comparing tissue biochemical composition and ovarian histology of wild female broodstock. Sixty (60) female broodstocks were used in the current study, consisting of 30 reared at sandy-muddy soil tank bottoms in captive conditions and 30 wild individuals collected from the haor basin during the breeding season. The fish reproductive state was investigated using the biometric and reproductive parameters, biochemical composition and levels of amino acids in the different tissues, and histological analysis of ovarian development. Results revealed that the biometrical parameters of wild and captive female broodstocks exhibited no remarkable difference (p > 0.05). Nevertheless, the wild fish had remarkably higher (p  0.05). However, two essential amino acids (EAA), i.e., lysine and phenylalanine, and two non-essential amino acids, i.e., glutamic acid and glycine, were highly significant differences (p < 0.05) in the oocytes and liver of wild broodstock compared to the captive-reared broodstock. On the other hand, the EAA, e.g., isoleucine, threonine, leucine, and arginine, were highly dominated in both wild and captive female brood oocytes and liver. The ovarian histological slides from each fish group showed three oocytes developmental stages that indicated the asynchronous-reproductive ovarian oocytes of this fish. This study may be useful to fully understand the factors affecting the spawning and reproduction of S. aor broodstock, crucial for management in captive conditions as well as conservation and protection for sustainable aquaculture management of S. aor