International Journal of Aquatic Biology

Effect of Hyssopus officinalis extract dietary supplementation on serological parameters, growth indices, and survival of common carp (Cyprinus carpio) against Aeromonas hydrophila

Maryam Yamini — 2025-10-25

The hyssop (Hyssopus officinalis) is known as a medicinal plant with antimicrobial and antioxidant properties. Despite a long history of medicinal use of H. officinalis, very few studies have been reported on the effect of H. officinalis on fish. Thus, the present study tried to investigate the effects of H. officinalis extract as a food supplement on serological parameters, growth indices, and survival of common carp (Cyprinus carpio) against Aeromonas hydrophila. For this purpose, the fish were divided into four treatments and fed with concentrations of 0, 250, 500, and 750 mg/kg H. officinalis extract in the diet for 60 days. The results revealed that the growth indices, including weight gain, length gain, specific growth rate (SGR), and food conversion ratio (FCR) in the treatments supplemented with H. officinalis extract, have no significant difference compared to the control treatment. Serological analysis showed that total protein increased in the treatments supplemented with H. officinalis extract, which was signi?cantly different in 500 and 750 mg/kg H. officinalis extract compared to the other treatments. Immunoglobulin signi?cantly increased in 750 mg/kg H. officinalis extract compared to the other treatments. There was no significant difference in the amounts of albumin, glucose, cortisol, cholesterol, triglyceride, creatinine, urea, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), lipase, and amylase of all treatments (P>0.05). Total antioxidant capacity (TAC) significantly increased in the treatment containing H. officinalis extract. Serum malondialdehyde (MDA) decreased in the treatments supplemented with H. officinalis extract. The lowest MDA was observed in 750 mg/kg H. officinalis extract, which was significantly different from other treatments. Relative survival percentage (RSP) against A. hydrophila increased in the treatments fed with H. officinalis extract. The highest RSP was observed in 750 mg/kg H. officinalis extract treatment. It can be concluded that dietary H. officinalis extract had a proper effect on immune system stimulation, antioxidant capacity, and resistance against A. hydrophila in the studied fish.

The impact of stocking density on the growth performance and survival rates of hybrid grouper juveniles (?Epinephelus fuscoguttatus × ?Epinephelus lanceolatus) reared in composite tanks

Xuan Diep Doan — 2025-10-25

Optimal stocking density is evaluated as a basic factor for the success of farming hybrid groupers (Epinephelus fuscoguttatus? × E. lanceolatus?), especially in Vietnam, where this species contributes significantly to marine aquaculture. This study was performed from July to November 2024 to evaluate the impact of different stocking densities (individuals m?³/ind m?³), including low (6 ind m?³), medium (9 ind m?³), and high (12 ind m?³), on the culture performance of the hybrid grouper juveniles raised in composite tanks. The juveniles, with an initial size of 4.15 g and 5.82 cm, were investigated in a 60-day completely randomized experiment with three replications. They were fed a combined diet of Artemia nauplii (instar I) and commercial pellet feed during the first 10 days, followed by pellet feed only for the remainder of the trial. The results showed no significant differences in survival rate (SR), feed conversion ratio (FCR), or coefficient of variation in weight (CV_W) among the different density groups (P?0.05). Nevertheless, key growth performance indicators, including mean weight (MW), mean length (ML), daily weight gain (DWG), daily length gain (DLG), specific growth rate in weight (SGR_W), and specific growth rate in length (SGR_L), were significantly reduced at a high stocking density (P?0.05). Additionally, there were no significant variations in rearing performance parameters between low and medium stocking densities throughout the rearing period, and a high SR range of 97.22-100% was recorded at the experimental end. The findings reliably demonstrate that hybrid grouper juveniles can be successfully reared in tank systems, with an optimal stocking density of up to 9 ind m?³.

Reproductive potential of male calanoid copepod Sinodiaptomus (Rhinediaptomus) indicus Kiefer: A potential live prey for fish larvae

Gopal Dharani — 2025-10-25

Copepods are a morphologically, physiologically, and ecologically highly diverse group with different reproductive characteristics and have evolved structural specialties of sperm form and spermatophore structure. These reproductive peculiarities are important for their implications in applied biology. Copepods are the preferred food for finfish and shellfish larvae due to their optimal size range and nutritive value. Although many copepod species are successfully mass-cultured, limited success is still reported in commercial-level production for use in aquaculture hatcheries. Unlike rotifers and Artemia, which reproduce by parthenogenesis and attain high-density production easily, copepods reproduce sexually, involving mate selection, a copulatory process, and leading to the transfer of spermatophores and fertilization of eggs. This necessitates an understanding of the reproductive biology of cultivable copepod species to establish effective culture protocols. The freshwater calanoid copepod Sinodiaptomus (Rhinediaptomus) indicus is a promising candidate for mass culture, and this article describes the reproductive biology of the male using histological and electron microscopic studies. The ultrastructure of the spermatozoon of this species is reported for the first time. Laboratory experiments showed long lifespan and high spermatophore production (34 in 25 days) in this animal, which is a key factor in deciding male-female ratio formulation in the inoculum for mass culture. It is suggested that the S. (R.) indicus could be an ideal species for mass culture and use as live feed in fish and prawn larval rearing.

Enhancing shrimp health and immunity through diets supplemented with indigenous intestinal lactic acid bacteria: Implications for Vibrio parahaemolyticus infections

Soni Andriawan — 2025-10-25

Lactic acid bacteria (LAB) have demonstrated significant potential as probiotic agents against various pathogens. The objective of this research was to investigate the potential of indigenous intestinal LAB in combating Acute Hepatopancreatic Necrosis Disease (AHPND) in Litopenaeus vannamei. The study ultimately identified the probiotic potential of Enterococcus faecalis isolated from shrimp intestines, focusing on its adaptability to varying salinity and pH levels, as well as its antibacterial efficacy. In this study, L. vannamei was fed freeze-dried E. faecalis combined with commercial feed to stimulate its immune system. Immune responses were assessed by measuring total hemocyte count (THC), phenoloxidase (PO) activity, respiratory burst (RB), transglutaminase (TG) activity, lysozyme activity, and hemocyte phagocytosis. Additionally, specific growth rate (SGR), weight gain (WG), feed conversion ratio (FCR), and survival rate (SR) were measured to assess the shrimp's growth performance. The experimental design included five treatments (0, 1, 2, 3, and 4 g of freeze-dried E. faecalis per kg of commercial feed), with each treatment consisting of four replicates. The results indicated that the T4 dosage was optimal for enhancing immune responses and growth performance while reducing mortality compared to other treatments. This research adds to the growing body of evidence supporting the use of E. faecalis as a probiotic in mitigating Vibrio parahaemolyticus infections.

New data on the parasites and parasite communities of Rutilus rutilus (Linnaeus, 1758) from the Danube River, Bulgaria

Radoslava Zaharieva — 2025-10-25

The present study aims to provide new data on the parasites and the first data on the parasite communities of the roach Rutilus rutilus (Linnaeus, 1758) from the Bulgarian section of the Danube River. The fish were caught in 2019-2021 from three biotopes (Koshava, Kudelin, and Novo Selo). Fish samples were collected during spring, summer, and autumn. A total of 152 R. rutilus specimens were examined. Nine helminth species were isolated: three species of Trematoda, two Cestoda, two Acanthocephala, and two Nematoda. The component community and infracommunity of the roach from the Danube River, Kudelin biotope, were examined. Rutilus rutilus is a new host record for six helminth species in Bulgaria.

Using artificial intelligence to predict aquatic pollution: A comprehensive review

Saif Al-Deen H. Hassan — 2025-10-25

Water contamination, or aquatic pollution, is a significant problem that endangers ecosystems, people's health, and the global economy. Laborious, expensive, and inadequate for real-time evaluations, traditional approaches to tracking and forecasting aquatic contamination include substantial manual sampling and laboratory testing. Pollutants and their origins are already complex, and the wide variety of chemical structures they contain further complicates matters. Because of these constraints, there is an ongoing, intense need for reliable predictions of pollution levels. The most promising method is artificial intelligence (AI), which can effectively interpret noisy data and handle nonlinear systems. When it comes to forecasting different types of water contamination, Artificial Neural Networks (ANNs) are among the most promising advanced AI models. To improve the forecasting accuracy of artificial neural networks (ANNs) for certain classes of pollutants, hybrid techniques, including radial basis function networks and small-world networks, have been developed. The field of water pollution research may also find success with Recurrent Neural Networks (RNNs) and Convolutional Neural Networks (CNNs). The purpose of this study is to shed light on research into how AI, and more specifically sophisticated models such as artificial neural networks (ANNs) and deep neural networks (DNNs), might improve the precision and effectiveness of pollution prediction.

Age, growth, and population dynamics of the Shovelnose catfish, Arius subrostratus (Valenciennes, 1840) in Cochin estuary, India

Ambily V — 2025-10-25

Population parameters studies of Shovelnose catfish, Arius subrostratus, from the Cochin estuary were conducted to determine age, growth, mortality, yield per recruit, and exploitation rate. Length frequency data of 1,205 species were collected from different landing centres of the Cochin estuary for this estimation. The Von Bertalanffy growth model is described as Lt = 364 (1-e ^{–0.53 (t+0.023}) from the findings. The values of L? and K were calculated to be 364 mm and 0.53, respectively. The estimated lifespan of the catfish, based on the present study, is 5.43 years. The study also revealed total mortality (Z), natural mortality (M), fishing mortality (F), and exploitation rate (E) as 1.56 y^-1, 0.59 y^-1, 0.97 y^-1, and 0.62, respectively. The recruitment pattern of A. subrostratus exhibited a single peak throughout the study period. The present findings revealed overexploitation of the species in the Cochin Estuary and suggested some management measures to ensure its conservation.

Effects of salinity on rearing performance of bighead catfish (Clarias macrocephalus Günther, 1864) juveniles

Nguyen Le Hoang Yen — 2025-10-25

Expanding the production of bighead catfish (Clarias macrocephalus Günther, 1864), a key freshwater species in Vietnamese aquaculture, into brackish water environments is essential in light of increasing saline intrusion into freshwater ecosystems driven by global climate change. A completely randomized design with three replicates was conducted in 0.5 m³ composite tanks to evaluate the effects of salinities (0, 2, 4, 6, and 8‰) on the rearing performance of juvenile C. macrocephalus. The juveniles (11.21 g and 11.49 cm) were stocked at a density of 45 individuals per tank (ind tank?¹) and fed Aquagreen commercial pellets containing 30% crude protein. After 180 days of culture, the highest growth performance was observed at 2‰ salinity and declined significantly at salinities ? 4‰ (P?0.05), likely contributing to significantly reduced productivity at 8‰ (P?0.05). Survival rates remained stable between 2 and 8‰ (P?0.05) and were significantly higher than those at 0‰ (P?0.05). Although growth performance at 0‰ was only slightly lower than that at 2‰ (P?0.05), the significantly lower survival rate at this salinity likely contributed to the significant decrease in productivity (P?0.05). The coefficient of variation in weight (CV_W) was significantly higher at salinities of 2-4‰ compared to other treatments (P? 0.05), but it ranged from 3.33 to 6.64% in tested salinities (0-8‰), which fell within the ideal range for fish culture. Based on the findings, 2‰ salinity is recommended as optimal for juvenile C. macrocephalus culture.

Tubificid worms (Oligochaetes: Naididae) in the sediments of the Euphrates River, Iraq

Ilham Obaed — 2025-10-25

A total of 1557 tubificid worms were collected from the sediments of six sites on the middle sector of the Euphrates River and its branches. The collected species were identified according to their morphological characteristics as Branchuria sowerbyi Beddard, 1892? Limnodrilus hoffmeisteri Claparède, 1862? L. hoffmeisteri complex IX, L. claparedianus Ratzel, 1868? L. cervix Brinkhurst, 1963? Tubifex tubifex (Müller, 1774)? Ilyodrilus templetoni (Southern, 1909) and T. blanchardi Vejdovský, 1891. Ilyodrilus templetoni and T. blanchardi were new records for the Iraqi fauna, and their identification was confirmed by molecular analysis using the 18S rRNA gene. Their sequences were deposited in GenBank under accession numbers PQ275504 and PQ275628, respectively.

Tissue-specific accumulation and species-level variability of microplastics in four freshwater fish from the Dez River, Iran

Zahra Mousavi — 2025-10-25

Microplastics (MPs) are emerging contaminants of global concern due to their persistence, bioaccumulation potential, and implications for both aquatic ecosystems and human health. This study explored MP contamination in four economically important freshwater fish species—Carasobarbus luteus, Arabibarbus grypus, Luciobarbus barbulus, and Oreochromis niloticus—collected from the Dez River in southwestern Iran. A total of 120 specimens (30 per species) were sampled near the Dez Dam using gill nets. Edible (muscle) and inedible (skin and gastrointestinal tract) tissues were analyzed separately for MP content following alkaline digestion with 10% KOH and vacuum filtration. Visual identification under a stereomicroscope was used to quantify and categorize MPs by color. Microplastics were detected in all species and tissue types, with significant interspecific variation. Carasobarbus luteus exhibited the lowest MP burden, significantly lower than O. niloticus and L. barbulus. No significant differences were found among tissue types, suggesting widespread tissue distribution. Color composition varied across species, with black MPs being the most abundant. Notably, green MPs were only observed in O. niloticus and L. barbulus. These findings highlight the impact of ecological traits, including feeding behavior and habitat use, on the risk of MP exposure. The detection of MPs in edible tissues highlights potential food safety concerns and underscores the need for routine monitoring of freshwater fish in affected river systems. This study reports the first evidence of MP contamination in fish from the Dez River and contributes to the growing body of data on freshwater plastic pollution in understudied regions.