Asian Journal of Fisheries and Aquatic Research
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Molecular Identification of Microbacterium barkeri: A Novel Approach to Enhancing Tilapia Growth in Biofloc Systems
No full textThis study focuses on the isolation and molecular identification of Microbacterium barkeri from soil samples and evaluates its potential application in biofloc systems for sustainable aquaculture. The bacterium was identified using morphological, biochemical, and molecular techniques (16S rRNA gene sequencing), confirming its identity through BLAST analysis (99.8% similarity to M. barkeri). The study investigated its role in ammonia and nitrite reduction, biofloc formation, and tilapia (Oreochromis niloticus) growth performance. Results indicate that M. barkeri significantly improves water quality, enhances nutrient cycling, and promotes fish growth. The optimal bacterial concentration (10⁶ CFU/mL) resulted in higher growth rates, better feed conversion efficiency (FCR), and increased survival compared to the control. These findings highlight M. barkeri as a promising microbial candidate for biofloc technology (BFT) in aquaculture, offering an eco-friendly alternative to improve water quality and fish productivity
Effects of Two Feed Additives (Complex Enzyme CE805 and Seafood Flavor II) in Local Feed on some Zootechnical Characteristics of Oreochromis niloticus Fry
No full textObjective: this study aimed to evaluate the combined effect of two feed additives (Complex Enzyme CE805* and Seafood Flavor II*) in the manufactured feed on some zootechnical characteristics of Oreochromis niloticus fry.
Study Area: The study was carried out at the Dibamba aquaculture farm in the locality of Logbadjeck located in the Littoral Region of Cameroon, Sanaga maritime Department, Dibamba district.
Methodology: A total of 600 single-sex fry of Oreochromis niloticus with an average weight of 0.95 ± 0.01 g were distributed in 24 happas of dimensions 0.3*0.5*0.5m3 each and were installed in a circular tank of dimensions 4m3 operating in open circuit. Eight (8) feed rations were used, one of which is a commercial feed available on the local market T0+: commercial feed and the other seven all lipoprotein, iso-lipidic and iso-energetic were formulated T(E0%; A0%): local feed formulated with 0% enzyme and 0% flavor, T(E0.125%; A0.01%): local feed formulated with 0.125% enzyme and 0.01% flavor, T(E0.125%; A0.0125%): local feed formulated with 0.125% enzyme and 0.0125% flavor, T(E0.125%; A0.0150): local feed formulated with 0.125% enzyme and 0.0150% flavor, T(E0.1%; A0.0125%): local feed formulated with 0.1% enzyme and 0.0125% flavor, T(E0.150%; A0.0125%): local feed formulated with 0.150% enzyme and 0.0125% flavor, T(E0.175%; A0.0125%): local feed formulated with 0.2% enzyme and 0.0125% flavor, in a completely randomized design repeated three times.
Results: The following results were recorded: the significantly highest survival rate (P > 0.05) (81.33 ± 2.30%) was recorded with subjects fed T(E0.150%; A0.0125%). The mean daily weight gain (0.16 ± 0.06 g/d), specific growth rate (2.21 ± 0.05%/j) and condition factor K (1.76 ± 0.09) were significantly higher (P > 0.05) and the lowest feed conversion ratio (1.69 ± 0.07) (P < 0.05) were recorded with diet T(E0.175%; A0.0125%).
Conclusion: Enzymes and flavors combined at respective doses of 0.175% and 0.0125% can be used to improve the digestibility and attractiveness of locally produced feeds
Lead a Heavy Burden: The Science, Struggles and Solutions for a Cleaner Future
No full textHuman activities bring a growing risk of heavy metal harm to water systems worldwide, especially from lead. Freed lead settles and builds up in water bodies, posing a danger to organisms higher in the food chain. Lead poison causes cell strain and harms nerve cell; in addition, it weakens the defence systems of aquatic organisms, which lowers their health and upsets the balance of life. New methods such as cleaning pollutants with microbes, plants and enzymes as well as nanotechnology-based solutions offer possible ways to cut lead waste. Other rules like the Clean Water Act or Resource Conservation and Recovery Act intend to stop or control lead waste. This paper explores the sources, accumulation mechanisms, impacts and innovative technologies to lower lead waste in aquatic systems. Essential steps to remove lead pollution benefit nature’s health as well as human health, giving lasting improvements for water habitats plus overall public health
Isolation and Characterisation of Indigenous Zinc Solubilising Microbes and their Probiotic Potentiality in Aquatic Ecosystems of Malawi
No full textIn this study, zinc solubilizing microorganisms (ZnSM) were isolated from the rhizospheres of aquatic plants, water and benthic soils of Malawi aquatic ecosystem with the aim of having cheap and environmental friendly biofertiliser that have probiotics traits in Malawi. Several studies have shown potentiality of indigenous ZnSM in biofertiliser development, but little is known about the presence of indigenous ZnSM and having probiotic traits in Malawi aquatic ecosystem. Isolates were screened for solubilisation traits using basal medium with three amendments of insoluble zinc (zinc carbonate, oxide and phosphate) supplemented by the characterization of plant-growth-promoting (PGP) and probiotic traits. Molecular characterization using 16S rRNA gene and biochemical test were used in identification and characterisation. Isolates candidacy was based on solubilisation index (SI) of above 1.5 complimented by production by diverse plant growth promoting and probiotic traits. Eight isolate namely Serratia marcescens, Enterobacter wuhouensis, Serratia surfactantfaciens, Serratia nematodiphila, Alcaligenes faecalis, Bacillus altitudinis and Klebsiella pasteurii were selected as potential candidates for development of zinc based biofertiliser. The study revealed that zinc solubilising microbes have great potential in probiotic development evidenced by production of amylase. The study has revealed and showed that Bacillus altitudinis strain had no site specificity and had highest potential in biofertiliser and probiotic development shown by solubilisation index of 4.7, 3.4 and 4 for zinc oxide, carbonate and phosphate respectively. Isolates solubilisation quantification was based on the type of inorganic zinc indicating that some of these microbes may be site specific based on the type of inorganic zinc available. The pH of the culture broth was found to be decreased in the range of 3.33 to 3.35 indicating that solubilisation is based on acid extrudes by the microbes. The study has given an insight of potentiality of indigenous microbes from aquatic ecosystem in the development of biofertiliser and probiotics in Malawi
Fishing Effort and It’s Impact on Fisher’s Economy: A Case Study of Chandakhal Wetland, Dhubri, Assam, India
No full textFishing effort is the number of days a fisher goes for fishing in the waterbody. The present study enquires about the impact of fishing effort on the fishing economy of the fishers associated with Chandakhal wetland of Dhubri, Assam, India. It is an analytical study based on the data collected through interviews and personal observation. The respondents of the study are the fulltime fisher men (40 numbers out of total 43 numbers) dependent on the wetland. The observation comprises finding of 70% of the respondents having fishing efforts varying between 151 – 200 fishing days and 30% has 201 – 250 fishing days. The summary statistics of the data of annual fishing days calculates the mean fishing day as 187. The regression analysis considering the Annual per capita fishing income as dependent variable and the Annual fishing days as the independent variable, the coefficient of correlation (R) is found to be 0.275 and coefficient of determination (R2) is found to be 0.075. The result is considered not significant (P = 0.086). It can be said that only 7.5% of the variation in the Annual per capita income is expressed by fishing effort in terms of the Annual fishing days in the present study
Estimation of Microbial Abundances and Their Respiration Rates in a Specialized Coastal Water Body
No full textMicrobial communities in an ecosystem are crucial for having active participation in shaping the biological and biochemical cycles of this ecosystem. In this study, we estimated marine bacterial counts and the microbial respiration rates in seawater samples collected from Gorliz beach, Bilbao, Spain, using DAPI (4′,6-diamidino-2-phenylindole)-based epifluorescence microscopy and optical oxygen sensors. The microbial density was 1.6 × 10⁶ cells/mL (± 47,948 SE; Standard Error), which is consistent with values typically reported for temperate coastal regions. In addition, microbial respiration rate based on the oxygen consumption was around a mean of 0.0127 μmol O₂/L/h (± 0.0026 SE) over 14 hours of incubation in the dark. These findings suggested an abundant and meaningful active microbial community in this coastal ecosystem, highlighting the critical role of microorganisms in regulating coastal ecosystem dynamics, local oxygen budget, and carbon biogeo-cycling. Hence, this study underlines the need for sequential, spatial, and temporal investigations of microbial communities and their biochemical processes in response to environmental changes and anthropogenic activities
Wastewater Generation and Pollutant Loads in Coastal Regions of Ba Ria–Vung Tau, Southern Viet Nam: Current Status and Future Projections
No full textThis study quantifies and projects pollutant loads from key wastewater sources in Ba Ria – Vung Tau (BRVT), a rapidly urbanizing and industrializing coastal province in southern Vietnam. An integrated methodological framework combining emission factor analysis, statistical projection, and Vietnamese national discharge standards was applied to estimate current and future pollutant loads across domestic, industrial, aquaculture, and stormwater sectors.
Currently, domestic wastewater is the dominant source, generating approximately 91,343 m³/day, with 95% treated in centralized plants. Industrial discharges totaled 47.3 × 10³ m³/year and are projected to exceed 74.1 × 10³ m³/year by 2035, coinciding with a shift toward stricter effluent standards. Aquaculture produced nearly 18,000 tonnes of fish and mollusks, releasing an estimated 1,800 tonnes of nitrogen and 360 tonnes of phosphorus annually, with production expected to rise by 50% by 2030. Stormwater runoff contributed roughly 12,000 tonnes of suspended solids and hydrocarbons per year, with future increases expected under climate change.
Beyond conventional pollutants, emerging contaminants such as microplastics and pharmaceutical residues are increasingly detected, posing new risks to seafood safety, biodiversity, and human health. Sustainable management requires a multisectoral approach that integrates advanced wastewater treatment technologies, green infrastructure, and capacity-based aquaculture zoning. Enhancing monitoring of emerging contaminants, promoting cleaner industrial production, and improving stakeholder participation are also essential to minimize environmental and public health risks. The findings provide a scientific foundation for adaptive wastewater governance aligned with the Sustainable Development Goals, supporting the province’s transition toward resilient and environmentally responsible coastal development
Effectiveness of Wastewater Treatment Plant (WWTP) Based on Physical and Chemical Parameters for Shrimp Pond Wastewater Management in Tasikmalaya
No full textAims: This study aims to evaluate the effectiveness of the Wastewater Treatment Plant (WWTP) in managing shrimp pond wastewater in Tasikmalaya based on physical and chemical parameters.
Study Design: A non-experimental design using a survey approach was applied through in situ field measurements and ex situ laboratory analysis. Water samples were collected in triplicate from four sampling stations.
Place and Duration of Study: The study was conducted at an intensive shrimp (Litopenaeus vannamei) culture facility in Tasikmalaya Regency, West Java, Indonesia. Sampling was performed at four stations (inlet, pond, WWTP, and outlet) during three cultivation phases between November 2024 and March 2025.
Methodology: Samples were collected during three different shrimp cultivation phases and analyzed for temperature, brightness, total suspended solids (TSS), biological oxygen demand (BOD), dissolved oxygen (DO), pH, ammonia, and phosphate. Statistical analysis using one-way ANOVA (α=0.05) was performed to evaluate differences between stations.
Results: The WWTP showed high efficiency in reducing ammonia (92%) and moderate efficiency for TSS (41%), while reductions in BOD (17%), phosphate (13%), and pH (5%) were relatively low. The increase in DO was only 12%, and temperature and brightness at the outlet did not meet the seawater quality standards.
Conclusion: The probiotic-enhanced WWTP effectively reduces nitrogenous pollution, particularly ammonia, through biological nitrification by Nitrosomonas and Nitrobacter species. However, the system requires optimization including: (1) enhanced aeration capacity to increase DO levels for improved BOD degradation, (2) implementation of anaerobic-aerobic zones for biological phosphate removal, (3) extended hydraulic retention time, and (4) addition of chemical precipitation for phosphate control before discharge into natural waters
Dietary Analysis of Sardinella maderensis (Lowe, 1938) in the Marine Waters off the Latakia Coast (Syria), Eastern Mediterranean: A Two-Year Seasonal Study
No full textDietary studies play a vital role in understanding the balance of marine ecosystems and sustainable fishery practices. This research examines the feeding habits of Sardinella maderensis, a commercially important Clupeidae species, in the marine waters off Latakia, eastern Mediterranean.
1,200 specimens were collected using gillnets and chinchilla nets, following local fishing practices, between October 20, 2021, and September 14, 2023. The sampled individuals displayed a standard-length range of 9.32–23.18 cm (mean 14.67±4.2 cm) and a weight range of 12.41–116.1 g (mean 44.28±28.37 g), with a maximum body height averaging 3.49±1.26 cm.
Dietary analysis indicated that S.maderensis is a planktivorous species, feeding on 15 planktonic species categorized into seven major groups: Crustaceans ranked first, with a relative importance of 46.95%, a frequency of 45.67%, and a total of 7832.50 points. This group included various types, such as copepods (e.g., Calanoidea and Cyclopidae) and malacostracans, including Euphausiacea, Mysidacea, and Decapoda (Penaeus and Crab megalopae). Detritus ranked second, with a relative importance of 19.60%, a frequency of 17.77%, and 2243.50 points. Phytoplankton followed, ranking third with a relative importance of 15.23%, a frequency of 13.55%, and 4158.88 points. Fish ranked fourth, with a relative importance of 8.95%, a frequency of 12.75%, and 2513 points. This group consisted of three species: Anguilliformes, Ophidion rochei, Trachurus trachurus, and partially digested fish remains. Polychaete worms showed a low contribution, with a relative importance of 0.75%, a frequency of 2.18%, and 255 points. Foraminifera contributed 0.32%, with a frequency of 1.02% and 71 points. Mollusks, represented by a single Octopoda individual, had the lowest contribution, with a relative importance of 0.01%, a frequency of 0.15%, and 20 points. These findings provide essential ecological data on S.maderensis feeding behavior, contributing to improved fisheries management and marine conservation efforts in the coastal waters of Latakia
An Empirical Analysis on the Breeding and Feeding Behaviour of Estuarine Rice Fish Oryzias melastigma (McClelland, 1839)
No full textThe breeding and growth characteristics of Oryzias melastigma were investigated under controlled laboratory conditions to assess its suitability for aquaculture. The species exhibited a short-generation time of 2 to 3 months that thriving in artificial-seawater at 28°C with a 14-hour light/10-hour dark-cycle. Sexual-dimorphism became apparent after one-month; with males developing a prominent anal-fin, aiding sex identification for experimental-populations. Feeding-experiments revealed that Oryzias melastigma, preferentially consumed early instar mosquito-larvae, showing high feeding-efficiency, particularly on smaller-prey. Additionally, the species demonstrated increased reproductive-success when supplemented with Ulothrix, suggesting its effectiveness as a feed to enhance egg-production and hatchling-survival. The sensitivity of eggs and larvae to pollutants like ammonia and CO2 indicates the species\u27 potential as a bio-indicator for water-quality. Statistical analysis of reproductive-output indicated that a mature-female, could produce over 1.5 million eggs annually; contributing to aquaculture-systems as a food-source for carnivorous-species. This potential-biomass, when applied to fish farming, could significantly enhance the production of species like Lates calcarifer. The study highlights breeding and feeding behaviour of estuarine rice fish, Oryzias melastigma