International Journal of Aquatic Biology

Effect of papaya (Carica papaya L) leaves flour on the growth performance and immunity parameters of whiteleg shrimp (Litopenaeus vannamei) challenged with Vibrio parahaemolyticus

2025-07-24T10:11:09+00:00

Whiteleg shrimp (Litopenaeus vannamei) is an economically valuable species that can be cultivated in Indonesia. One of the main challenges in this cultivation activity is the high disease-related mortality. One approach to preventing infectious diseases is to enhance the immune response by administering immunostimulants. Papaya (Carica papaya L.) can be used as an immunostimulant, as its leaves contain the proteolytic enzyme papain, which plays a role in protein breakdown (proteolytic activity), and the alkaloid Carpaine, which has antibacterial properties. The study employed a Completely Randomized Design (CRD) with 5 treatments and 3 replications. The treatments consisted of control+, control-, and papaya leaf flour at 2, 4, and 6%. Research parameters included survival rate (SR), specific weight growth rate, specific length growth rate, feed conversion ratio, blood glucose, phagocytic activity, and water quality, including temperature, pH, dissolved oxygen, salinity, and ammonia (NH₃⁺). The best treatment was P5 at 6%, which showed significant improvements in survival rate, specific weight growth rate, specific length growth rate, feed conversion ratio, and phagocytic activity.

Morphometry and fluctuating asymmetry of the gibel carp (Carassius gibelio) in bodies of water with different types of hydrology

2025-09-22T17:16:36+00:00

This work examines the morphometric characteristics and fluctuating asymmetry of gibel carp, Carassius gibelio (Bloch, 1782) populations in water bodies within the same basin under varying hydrological conditions in the Ob-Irtysh basin, Western Siberia. By conducting measurements and analyses of meristic features, we determined the extent to which fish morphological characteristics are influenced by their natural habitat and hydrological regime. Cluster analysis revealed that gibel carp populations from reservoirs with a permanent water supply share similar morphometric parameters and exhibit lower asymmetry than populations from isolated or irregularly filled reservoirs. As a result of morphometric assessment, fluctuating asymmetry was shown to be an important and convenient indicator of adaptive changes and the overall state of the population. The data obtained emphasize the need to account for hydrological factors in ecological and biological studies and in monitoring species threatened by habitat change. The results of the study can be useful in monitoring the state and restoration of aquatic ecosystems.

Evaluating optimal stocking density for the tank polyculture system of whiteleg shrimp (Litopenaeus vannamei) and all-male giant freshwater prawn (Macrobrachium rosenbergii) postlarvae

2025-10-13T07:20:58+00:00

Whiteleg shrimp (Litopenaeus vannamei) and giant freshwater prawns (Macrobrachium rosenbergii) are significant crustaceans in aquaculture, and they are compatible for bi-farming systems. This study assessed the best stocking density for a tank-based polyculture system comprising postlarval whiteleg shrimp and all-male giant freshwater prawns. The study used a completely randomized design with three replications. Whiteleg shrimp were stocked at four densities (5, 10, 15, and 20 individuals/m³—ind m?³), whereas all-male giant freshwater prawns were maintained at 5 ind m?³ in 4 m³ tanks with partial shading. After two months of rearing using a commercial pellet feed (42% crude protein), survival rates, as well as weight and length growth performance parameters (final mean weight, daily weight gain, specific growth rate in weight, final mean length, daily length gain, and specific growth rate in length) of both trial animals, were significantly higher at shrimp stocking densities of 5 and 10 ind m?³ than 15 and 20 ind m?³ (P?0.05). There were no significant changes in survival rates or growth performance parameters between densities of 5 and 10 ind m?³ (P?0.05). Productivity was significantly lower at 5 ind m?³ compared to other densities (P?0.05), while there were no significant differences among higher stocking densities (10-20 ind m?³) (P?0.05). The findings indicate that a stocking density of 10 ind m?³ for whiteleg shrimp and 5 ind m?³ for all-male giant freshwater prawn offers the optimal balance of growth, survival, and productivity in the experimental system.

Population structure, stock status, and management implications of longtail tuna (Thunnus tonggol) in the Natuna Sea, Indonesia

2025-11-12T01:35:53+00:00

This The Natuna Sea, a strategic and biodiverse marine area, supports significant fishery resources. This study investigated the population dynamics of longtail tuna (Thunnus tonggol), a species of considerable ecological and economic importance, to provide a scientific basis for sustainable fisheries management in the region. Monthly fork length data were collected throughout 2021 from drift gillnet catches landed at Pemangkat Fishing Port, West Kalimantan, and were analyzed using the FiSAT II software package. Key population parameters were estimated as: asymptotic length (L_?) = 114.45 cm, growth coefficient (K) = 0.36 year^-1, and theoretical age at zero length (t?) = - 0.2865 years. Natural mortality (M) was 0.65 year^-1, fishing mortality (F) was 0.58 year^-1, and total mortality (Z) was 1.23 year^-1. These values yielded a current exploitation rate (E) of 0.43. Recruitment was bimodal, occurring in March–April and August–September. The length at first capture (L_c) was estimated at 54.33 cm. The spawning potential ratio (SPR) was estimated to be 30%, a level considered above the minimum biological limit reference point for sustainability. The yield-per-recruit analysis demonstrates that the existing exploitation rate (E = 0.43) falls short of the rates necessary to attain maximum yield per recruit (E_max = 0.598) and the optimal yield per recruit (E_0.1 = 0.507). These findings suggest that the T. tonggol stock in the Natuna Sea is currently in a developing exploitation phase, with potential for carefully managed increases in fishing effort while ensuring long-term sustainability.

Dietary gold nanoparticles modulate the gut microbiota of Mystus vittatus (Bagridae): evidence from 16S rRNA amplicon sequencing

2025-09-26T19:52:51+00:00

We evaluated whether biosynthesized gold nanoparticles (AuNPs) used as a dietary supplement reshape the gut microbiota of Mystus vittatus using 16S rRNA (V3-V4) amplicon sequencing. Across all samples, we resolved 716 amplicon sequence variants (ASVs) spanning 20 phyla, 33 classes, 75 orders, 129 families, and 190 genera. AuNP-fed fish showed numerically higher richness and evenness than controls; however, alpha-diversity indices (Chao1, Shannon, and Simpson) and beta-diversity (unweighted UniFrac PCoA) did not differ significantly (P>0.05). Despite the lack of whole-community separation, several taxa responded to AuNPs. Genera detected as candidate biomarkers in univariate testing included Ralstonia, Rikenellaceae_RC9_gut_group, Candidatus Arthromitus, Family_XIII_AD3011_group, and Undibacterium, alongside a higher relative abundance of Bacillus—consistent with putative probiotic activity reported in fish. Community-function predictions with PICRUSt2 indicated enrichment of pathways related to amino acid and energy metabolism, nucleotide metabolism, and replication/repair in the AuNP group, whereas carbohydrate-focused pathways (for example, glycolysis and fructose/mannose metabolism) were relatively higher in controls. These results suggest that dietary AuNPs can shift microbiome composition and predicted functional potential toward profiles compatible with improved nutrient processing and immune readiness. Because functional inferences were derived from 16S marker data rather than shotgun metagenomes, they should be interpreted cautiously. We also note that community-level diversity differences represented trends rather than statistical separations. Overall, AuNP supplementation at 50 mg/kg produced measurable changes in the microbiome without disrupting the core phylum-level structure. These findings support further evaluation of AuNPs as a feed additive in aquaculture, including dose–response testing, validation using metagenomic or metatranscriptomic sequencing, and long-term safety assessments that track performance, disease outcomes, and environmental release.

Drought and flood footprint: An environmental analysis of plant biodiversity changes in Al-Hawizeh Marsh, Iraq

2025-12-18T14:02:27+00:00

This study aimed to assess environmental changes and degradation in Al-Hawizeh Marsh-Umm al-Naaj Pond, southern Iraq, from 2017 to 2023, focusing on plant diversity and its response to variations in rainfall, flooding, and water quality. It compared the wet season (2018/2019) with the severe drought season (2022/2023). Field surveys and data on the region's rainfall patterns showed a sharp annual variation. The 2018/2019 season recorded 413.6 mm of annual rainfall, resulting in complete flooding of the marsh (100% in the spring). In contrast, the drought seasons (2020/2021) saw rainfall of no more than 31.2 mm. The drought became more severe in the 2022/2023 season, as the AL-Hawizeh Marshes in Misan were flooded by only 5% of the area that could be flooded. The reduced freshwater releases associated with the drought led to a significant deterioration in water quality. In 2023, chloride (Cl) ion concentrations nearly doubled, and TDS and EC values ??increased significantly compared to 2018. The most severe impact of drought was on vegetation cover, where a radical ecological shift occurred between 2018 and 2023. In 2018, aquatic plants dominated (70%) of plant diversity. By 2023, this ratio had reversed, with terrestrial plants comprising (73%) of plant diversity, and 16 terrestrial plant species of Iraqi flora were recorded for the first time in the marshlands. The study confirms that climatic fluctuations, represented by the annual variation in rainfall, are the main determining factor for water levels in the marshes, and that periods of severe drought led to widespread structural deterioration in the region’s ecosystem, increased salinity, water pollution, and a complete shift in plant biodiversity towards terrestrial and halophyte species.

Isolation and characterization of amylase-producing Bacillus sp. ACoL20 isolated from the gut of flying fish, Cheilopogon intermedius

2025-11-05T12:48:46+00:00

: Bacterial enzymes associated with the gut of fish are known to aid in the digestion and nutrition of the host. In the present study, amylase-producing bacteria were isolated, identified, and characterized from the gut of flying fish (Cheilopogon intermedius). Isolation was performed on starch agar (SA) plates, and the isolated bacterial strains were qualitatively and quantitatively screened for amylase production. Among the isolates, strain ACoL20 exhibited the highest amylase activity, reaching 15.21 U.mg^-1 protein. Morphological, biochemical, physiological, and molecular analysis revealed that the isolate belongs to the genus Bacillus (86% homologous to B. paramycoides). Further qualitative assessment, through the measurement of the zone of hydrolysis, indicated that optimum amylase production occurred at 36 h at 40°C, with a wide range of pH tolerance (pH 6-9) when cultured in starch agar supplemented with 1% NaCl. These findings highlight the amylolytic potential of Bacillus sp. ACoL20 and its possible application in enhancing fish nutrition and other biotechnological processes.

Environmental filtering of benthic communities along the sediment trophic gradient in Ashtamudi Ramsar wetland of Kerala

2025-09-04T07:10:30+00:00

Ashtamudi Lake, a Ramsar-designated tropical estuarine wetland in Kerala, exhibits marked environmental gradients from marine to freshwater influence that strongly shape benthic community structure. To assess the role of sediment physico-chemical characteristics in regulating benthos, sediment and faunal samples were collected from five different locations during the post-monsoon season of the year 2023. Sediment analysis revealed marked differences, with pH values indicating overall acidic conditions (4.8-6.3), and organic carbon, nitrogen, and potassium increasing gradually toward inner stations such as Kidapram and Cherikadavu, reflecting terrestrial run-off and depositional enrichment. A total of 67 benthic taxa were recorded, with Neendakara showing the highest richness (47 species), dominated by marine families, while inner sites supported estuarine - freshwater tolerant families such as Veneridae and Corbiculidae. Richness indices (Margalef and Menhinick) showed progressive decline towards inland, and Pearson correlations indicated strong positive relationships of richness with nitrogen (r = 0.76), organic carbon (r = 0.67), and potassium (r = 0.61), as well as a moderate negative association with pH (r = –0.46). Cluster and ordination analyses (Jaccard similarity and CCA) also highlighted ecological layering from marine to freshwater regions in sediment quality status. This study highlights sediment trophic gradients and organic enrichment as key environmental filters structuring benthic diversity, underscoring the need for sediment management to maintain the ecological integrity of Ashtamudi Lake.

Stock assessment of the marine ornamental Vagabond Butterflyfish Chaetodon vagabundus Linnaeus, 1758 (Pisces, Chaetodontidae) and the Indo-Pacific sergeant Abudefduf vaigiensis (Quoy & Gaimard, 1825) from Iligan Bay, Southern Philippines

2025-01-30T13:26:17+00:00

The success of fisheries depends critically on the state of the fish stocks. In this study, a total of 1,188 fish individuals belonging to two species of Abudefduf vaigiensis (711), Chaetodon vagabundus (477) were investigated based on the samples collected from the waters of Iligan Bay, Southern Philippines. Population parameters were assessed using length-frequency data with FiSAT II software. The results showed positive correlations between length and weight. The values of b significantly (P<0.000) increased from 2.55 in C. vagabundus to 2.82 in A. vaigiensis. The growth and mortality parameters asymptotic length (L_?), annual growth rate (K), annual total mortality (Z), natural mortality (M), fishing mortality (F) and exploitation rate (E) were 15.75 cm, 0.430, 1.60, 1.24, 0.28 and 0.18 for A. vaigiensis and 14.70 cm, 0.700, 2.60, 1.73, 1.09 and 0.39 for C. vagabundus, respectively. A bimodal recruitment pattern of unequal strength was observed for both species. The result of the virtual population analysis (VPA) routine showed that most of the small and young fish were prone to natural losses, while bigger fish were mostly caught by the fisherman. Finally, the maximum sustainable yield (E_max) for the two species was higher than the exploitation level, indicating that these two ornamental reef fishes were in good condition in Iligan Bay.

The role of predigested plant protein in enhancing nutritional value, feed utilization efficiency, and growth performance of Nile tilapia, Oreochromis niloticus

2025-11-13T05:03:45+00:00

This study evaluated the effect of incorporating predigested Indigofera zollingeriana leaf meal as a partial substitute for soybean meal in the diet of Nile tilapia (Oreochromis niloticus) on feed utilization efficiency, protein efficiency ratio, growth performance, and survival rate. Predigestion was conducted using cellulase enzyme (1.2 g kg?¹) to hydrolyze complex fiber and protein compounds into more digestible forms. A Completely Randomized Design (CRD) was employed, with four dietary treatments: 0 (control), 25, 50, and 75% substitution of soybean meal with predigested Indigofera leaf meal, each containing 30% crude protein and an energy-to-protein ratio of 8.5-9.0 kcal g?¹. The feeding trial lasted six weeks using juvenile tilapia (2.39±0.12 g) stocked at a density of 50 fish m?² and fed three times daily to satiation. The results showed that predigestion enhanced the nutritional quality of Indigofera leaf meal, increasing protein content from 31.04 to 38.22% and reducing crude fiber from 15.53 to 13.10%. Increasing inclusion levels of predigested Indigofera leaf meal improved total feed intake (96.53-112.29 g), feed utilization efficiency (68.73-75.61%), protein efficiency ratio (2.29-2.52), and relative growth rate (4.22-5.84% day?¹). The highest final biomass (119.48 g) and survival rate (96.67%) were observed at the 75% substitution level, indicating that predigested I. zollingeriana meal supports efficient nutrient conversion and growth without adverse physiological effects. Water quality parameters, including temperature (24-28°C), pH (7.9-8.1), dissolved oxygen (3.5-4.7 mg L?¹), and ammonia (<0.15 mg L?¹), remained within optimal ranges throughout the rearing period. The findings demonstrate that predigested I. zollingeriana leaf meal can effectively replace up to 75% of soybean meal in Nile tilapia diets, improving feed efficiency, growth performance, and survival while supporting sustainable and cost-effective aquaculture practices.

Growth, molting, and tissue responses of Pacific whiteleg shrimp (Litopenaeus vannamei Boone, 1931) to garlic (Allium sativum) skin and guava (Psidium guajava) leaf extracts as dietary phytogenics

2025-11-06T09:19:37+00:00

The use of phytogenic feed additives has gained increasing attention in shrimp aquaculture as alternatives to synthetic growth promoters. This study evaluated the zootechnical, morphometric, and histological responses of Litopenaeus vannamei fed diets supplemented with garlic skin extract (GSE) and guava leaf extract (GLE). A 60-day feeding trial was conducted with four dietary treatments: Control, GSE, GLE, and a combined complex (GSE + GLE) diet. Growth parameters did not differ significantly among treatments, but numerical improvements in final weight and condition factor were observed in GLE-fed shrimp (9.02±1.76 g; 1.30±0.56). GSE-fed shrimp exhibited the highest biomass and survival, while the complex diet resulted in lower growth and survival relative to individual additives. Feed utilization outcomes were consistent with these trends, and strong positive correlations were recorded between survival and biomass (r=0.985) and between final weight and condition factor (r=0.932). Molting frequency increased significantly in GSE-fed shrimp (11.62±1.02%). Histological examinations showed intact hepatopancreatic tubules and muscle fiber integrity in GSE and GLE groups, whereas mild epithelial thinning and fiber disruption were observed in shrimp fed the complex diet. Overall, supplementation with GSE or GLE individually improved shrimp performance and tissue condition, indicating their potential as sustainable phytogenic additives for aquaculture.

Laboratory-scale removal of ciprofloxacin, levofloxacin, and amoxicillin from aqueous media using the green microalga Neochloris conjuncta

2026-01-05T08:01:46+00:00

The objective of this study was to evaluate and compare the laboratory-scale removal behavior of antibiotics with different chemical structures, viz., ciprofloxacin, levofloxacin, and amoxicillin, using the green microalga Neochloris conjuncta, with particular emphasis on concentration- and time-dependent removal dynamics. Batch experiments were conducted under controlled laboratory conditions in aqueous BG-11 medium supplemented with antibiotics at initial concentrations of 5, 10, 15, 20, 25, and 100 mg L?¹. Removal performance was monitored over exposure durations of 24, 72, 120, and 168 h, and residual antibiotic concentrations were quantified using HPLC-UV. The results showed that at low concentrations (5-10 mg L?¹), all three antibiotics were completely removed within 24-72 h. At intermediate concentrations (15-25 mg L?¹), a clear time-dependent decrease was observed, leading to complete removal within 120-168 h. At the highest concentration (100 mg L?¹), removal was slower; however, substantial reductions were still achieved, with residual concentrations after 168 h of 6.59 mg L?¹ for ciprofloxacin, 2.64 mg L?¹ for levofloxacin, and 4.13 mg L?¹ for amoxicillin. Removal efficiency followed the order amoxicillin > levofloxacin > ciprofloxacin, attributable to differences in molecular structure and chemical stability. Although the study was conducted under laboratory conditions using synthetic aqueous media and did not account for the complexity of real wastewater matrices, the findings provide valuable insight into the mechanisms of algal-mediated antibiotic removal. The results highlight the practical potential of N. conjuncta as an environmentally friendly and cost-effective biological agent for reducing antibiotic contamination in aqueous systems.