Journal of Fisheries (University of Rajshahi)
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First record of the symbiotic crab Harrovia elegans De Man, 1887 from west coast of India
Full text linkThe present study documents the first record of the crinoid-associated brachyuran crab Harrovia elegans De Man, 1887 from dense beds of the feather star Tropiometra carinata (Lamarck, 1816) in tide pools within the intertidal zone of the Simbor Coast, Gujarat, India. Previously, H. elegans has been reported with different crinoid species from limited localities in Indian waters, including Tamil Nadu and the Andaman and Nicobar Islands, typically at depths ranging from 5 to 200 meters. This report provides detailed morphological descriptions of H. elegans, along with information on its habitat preferences and regional distribution
Spawning dynamics and maturity patterns of the Indian squid, Uroteuthis (Photololigo) duvaucelii (A. d'Orbigny, 1835), along the southeastern coast of India
Full text linkUroteuthis (Photololigo) duvaucelii (A. d’Orbigny, 1835), is an economically important squid species along the southeastern coast of India. This study presents a comprehensive analysis of its reproductive biology, based on the specimens collected during an exploratory fishery resources survey in the region. The results provide valuable insights into the reproductive patterns of this important fishery resource. The overall sex ratio was 0.9:1 (Male:Female), indicating a predominance of females over males. The length at 50% maturity (L50) was estimated at 138 mm dorsal mantle length (DML) for Males, and 118 mm for females, showing that females tend to mature earlier. Observation of maturity stages revealed that sexually mature (stage V) males and females were found throughout the year, with a reproductive peak in April, though no spent individuals were observed during the study. The maximum number of total eggs recorded in the ovary was 69,629 with 841 mature ova. Potential fecundity ranged from 544 to 20,865 eggs, with an average of 9,114. Relative fecundity (RF) value ranged from 8 to 115, while potential reproductive investment (PRI) values ranged from 0.01 to 0.196. The maximum egg weight was observed between 1.6 and 1.7 mg. Histological examination of the ovary and oviduct (stages IV and V) confirmed that this species follows an iteroparous spawning strategy, characterised by multiple spawning events throughout the year
Dietary emamectin benzoate alters the gill and spleen histoarchitecture of monosex Oreochromis niloticus fry
Full text linkOral administration of the antiparasitic veterinary drug emamectin benzoate is recommended to control infectious ectoparasites, whose biosafety and effect on vital organs are unknown in several fish species. This study evaluated the influence of dietary emamectin benzoate on the histopathology of hitherto understudied organs, such as gills and spleen of all-male Oreochromis niloticus fry at the recommended dose of 50 µg and an overdose of 500 µg kg body weight–1 day–1 for 7 days. The fry recorded dose-dependent discrepancies in feed intake, survival and biomass. Histologically, noticeable pathological changes in the gill and spleen tissues were documented in both groups. The pathological alterations in the fry fed the recommended dose and increased severity in the overdosed groups indicated the toxic nature of emamectin benzoate and signified exercising caution during its application in tropical aquaculture
Growth and nutrient profile of Tetraselmis chuii under different urea concentrations: implications for sustainable uses
Full text linkNitrogen is regarded as one of the most important nutrients for algal cells, having a direct impact on the growth and biochemical contents of microalgae. The goal of this research was to compare the growth and proximate components of Tetraselmis chuii cultivated in various urea concentrations as an available source of nitrogen. Results disclosed that T. chuii cultivated in urea at 93.4 mg L–1 N had higher cell density, biomass, and optical density compared to 11.67 mg L–1, 23.35 mg L–1, 46.7 mg L–1, and 233.5 mg L–1 N, respectively. Protein content was highly significant for urea at 233.5 mg L–1 N concentration compared to other concentrations. In contrast, higher carbohydrate content was found at 11.67 mg L–1 N compared to other concentrations of urea. Thus, the current study found that raising or decreasing urea concentrations had a substantial effect on the growth and proximate composition of indigenous marine T. chuii, and the highest biomass was recorded at 0.0145 g L–1 (dry biomass) from 93.4 mg L–1 N. These findings have implications for the cultivation of microalgae for various applications, including biofuel production, wastewater treatment, mariculture developments, and a sustainable blue economy in Bangladesh
The effect of different dietary protein levels on the water quality and reproductive performance of Nile tilapia (Oreochromis niloticus) broodstock in biofloc system
Full text linkThis study investigated the effect of protein levels on the water quality and reproductive performance of Nile tilapia (Oreochromis niloticus) in the biofloc system. Three isocaloric diets with different protein levels (32%, 38%, and 44%) were formulated. A total of nine one-tone tanks with a water holding capacity of 0.9 tons were prepared and equipped with the necessary materials to form biofloc. Seventy-two female and thirty-six male fish were tagged, numbered, and randomly released into the tanks at a female: male ratio of 2:1. The results showed that the lowest amount of TAN (0.21 mgL–1), NO2, and NO3 were observed in the treatment of 32% protein. Mean final weight in the 32% and 38% treatments was 350 and 356 g, respectively, with no significant difference. The highest absolute fecundity (654) was observed in the 32% group, but no significant difference was found between the absolute fecundity of the 38% and 44% groups. The longest interval (17.8 days) was observed in the 44% protein group. The percentage of fertilization and hatching did not significantly differ between the groups. The highest percentage of fertilization (93%) and hatching (89%) were observed in the 32% protein group. The total number of eggs per female fish did not differ between the 32% (12840) and 38% (12670) groups, while the 44% group had the lowest number of eggs (12040). The present study showed that a dietary protein level of 32% is optimal for water quality and reproductive performance of Nile tilapia in the biofloc system
Anesthetic efficacy of Mentha piperita and Mentha spicata essential oils on rainbow trout (Oncorhynchus mykiss)
Full text linkIn the present study, anesthetic effects of Mentha piperita and Mentha spicata essential oils were investigated on rainbow trout. For this purpose, five treatments of the essential oils (50, 100, 200, 300 and 500 mg L–1 concentrations) and one control (2-phenoxyethanol; 0.3 ml L–1 concentration) have been used for rainbow trout (Oncorhynchus mykiss; mean weight of 15 g). In addition, the mean lethal doses (10 minutes LC50 concentration) of the essential oils were also determined. Mentha piperita and M. spicata essential oils at 200, 300 and 500 mg L–1 doses showed better anaesthetic effect than control (p < 0 .05). The ideal anesthetic dose of each essential oil was 200 mg L–1 (p < 0.05). At this concentration, deep anesthesia (Stage IV) induction time for M. piperita and M. spicata on rainbow trout were found as 169.66 s and 65.0 s, respectively. The recovery times at 200 mg L–1 concentration were 188.0 s for M. piperita and 65.33 s for M. spicata. The lethal dose of both essential oils in fish was 150 mg L–1. This study suggests that the essential oils of M. piperita and M. spicata are both effective anesthetic agents for rainbow trout
First report of Halimeda magnicuneata Verbruggen & Dumilag 2020 from the northern coast of Sri Lanka
Full text linkThe genus Halimeda is a group of calcifying green algae that play a crucial role in sediment production and reef stabilisation. During a field survey in November–December in Mathagal, Northern Sri Lanka, the previously unreported species Halimeda magnicuneata was identified. This marks the first record of the species in Sri Lankan waters and was confirmed through morphological analysis, segment cross-sections and comparisons with established taxonomic descriptions. The collected specimens had segment widths of 8–21 mm (mean 13.1±4.6 mm), lengths of 9–17 mm (mean 9.9±3.8 mm) and thicknesses of 0.50–1.25 mm (mean 0.75±0.31 mm). The holdfast measured 4–8 mm (mean 6.17±2.02 mm), with an overall algal height of 95–110 mm (mean 102.3±7.51 mm). The branching pattern was dichotomous, a typical characteristic of the genus. The species was found attached to coral rubble in shallow waters (~3 m depth). The microscopic view of segment surface showed hexagonal cells with thick cell walls and cross-section of segment revealed medulla and cortex which consists of layers of primary and inflated secondary utricles. These microscopic characteristics further authenticated the species identification. The present finding contributes to the growing knowledge of the region’s marine biodiversity and highlights the importance of continuous biodiversity assessments. The documentation of H. magnicuneata underscores the need for further studies on its ecological interactions, distribution patterns and response to environmental changes
First record of the toxic shadow goby Yongeichthys nebulosus (Gobiidae: Gobiinae) from West Bengal, eastern India
Full text linkHerein, the first specimen-based record of Yongeichthys nebulosus (Forsskål, 1775) (Gobiidae) is reported from West Bengal, eastern India. Three individuals were collected from mangrove-associated waters in the Indian Sundarbans, one of which was preserved as a voucher specimen at the Zoological Survey of India. This record represents a north-eastward range extension for the species, which has previously been recorded from other parts of the Indian coast, including the neighbouring state of Odisha. Morphological and meristic features of the voucher specimen are consistent with published diagnoses. The discovery highlights the importance of specimen-based documentation for accurately recording species distributions and emphasises the need for sustained biodiversity monitoring in estuarine habitats
Drying and smoking of fish: nutritional significance, safety concerns and emerging technologies for food security
Full text linkThe global demand for fish and fishery products has heightened the need for effective preservation methods to ensure food security and reduce post-harvest losses. Among these, drying and smoking remain the most widely practiced, traditional yet scientifically important techniques, particularly in regions lacking modern refrigeration. Drying, achieved through sun drying, solar or mechanical dryers, reduces microbial activity and enzymatic degradation, while smoking, through cold, warm or hot methods, imparts flavour and enhances preservation. These products are rich in high-quality protein, omega-3 fatty acids, vitamins and minerals, contributing significantly to human health and nutrition. However, microbial contamination, lipid oxidation, pesticide residues and heavy metal accumulation present safety concerns, especially under unhygienic processing conditions. Modern innovations such as vacuum packaging, automated smoking systems and electrostatic smoking improve safety and quality, while climate change poses new risks to traditional sun drying and smoking. Consumer perception is shifting towards safer and more hygienic products, while international regulations and standards such as Codex Alimentarius, EU directives and FSSAI guidelines play a crucial role in ensuring compliance and supporting trade. Furthermore, dried and smoked fish hold nutraceutical potential as affordable sources of protein and bioactive compounds in functional foods and supplements. Emerging technologies, including intelligent packaging, vacuum and liquid smoking and AI- or IoT-enabled dryers, offer sustainable solutions for consistent quality and extended shelf life. By integrating traditional practices with modern innovations and regulatory frameworks, dried and smoked fish can continue to play a pivotal role in ensuring global food and nutritional security
Using brine shrimp to assess the performance of Annona muricata–zinc oxide nanoparticles: characterization and evaluation of photocatalytic, antibacterial and antibiofilm properties
Full text linkThe development of multifunctional nanoparticles through green synthesis is an important advancement in nanotechnology, addressing the growing need for effective antimicrobial agents against drug-resistant pathogens and efficient photocatalysts for environmental remediation, while also necessitating thorough eco-toxicological assessments to ensure their safe application, particularly in sensitive ecosystems like fisheries. In this study, we investigated the antimicrobial activities, photocatalytic activity and eco-friendly assessment on zooplankton crustacean Artemia salina and phytochemical properties of biosynthesized zinc oxide nanoparticles using aqueous fruit extract of Annona muricata (Am-ZnO NPs). The synthesized Am-ZnO NPs was characterized using UV–visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). XRD analysis revealed the crystalline nature of Am-ZnO NPs. TEM analysis showed that the Am-ZnO NPs were spherical in shape with a size between 50 and 100 nm. In addition, Am-ZnO NPs showed antibacterial and antibiofilm activity against multiple drug resistance (MDR) Gram positive, Enterococcus faecalis bacteria. Am-ZnO NPs showed significant photocatalytic activity against two different organic dye pollutants namely methylene blue and acridine orange under both sunlight and UV light exposure. Ecotoxicity assessment of Am-ZnO NPs (25, 50, 75, and 100 μg mL–1) showed no toxicity against non-targeted marine crustacean Artemia salina at low concentration and slightly toxic at high concentration (100 μg mL–1). Together, the results suggest the potential application of Am-ZnO NPs against multiple drug resistance microbes and photocatalytic activities