Journal of Fisheries (University of Rajshahi)
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Impact of environmental factors on the dietary preferences of Salmophasia bacaila in the Dhepa River, Bangladesh
Full text linkThis study investigates the environmental variability and gut contents of an indigenous fish chela (Salmophasia bacaila) in the Dhepa River, Bangladesh. We conducted fish sampling and measured water quality across three sites from September 2017 to February 2018. The results revealed significant fluctuations in water temperature, dissolved oxygen, and pH (PERMANOVA: p = 0.001). There was spatio-temporal variation in water transparency (PERMANOVA: p = 0.001). The prey analysis identified 13 prey groups in the diet of fish, predominantly consisting of phytoplankton (92.9%), while zooplankton contributed only 7.1%. Twenty phytoplankton and seven zooplankton genera were recorded in the guts, with significant temporal variations in prey diversity (PERMANOVA: p = 0.010). These findings highlight that S. bacaila are primarily plankton feeders, with shifts in prey diversity driven by environmental factors in the Dhepa River. This research enhances our understanding of ecological dynamics and the relationship between S. bacaila and their prey in riverine ecosystems
Optimizing paddy spacing for co-production: effects on rice-fish yields and soil-water quality in integrated farming systems
Full text linkIntegrated rice-fish farming (IRFF) is a promising agronomic strategy that enhances crop and fish productivity while improving soil health and resource use efficiency. This study aimed to assess the effects of different rice planting spacing on the growth and yield of rice and fish and evaluate soil fertility and water quality within an IRFF system. A field experiment was conducted using four (T1–T4) planting spacing; T1: 10 cm × 10 cm, T2: 15 cm × 15 cm, T3: 20 cm × 20 cm, and T4: 25 cm × 25 cm. Each treatment with three replicates was randomly allocated in a randomized complete block design. Growth and yield parameters of rice and fish were measured along with soil and water quality indices. Data were analyzed using ANOVA and Tukey’s test. Spacing influenced both rice and fish performance significantly. The 15×15 cm spacing provided the best balance, supporting high yields for both rice and fish without adverse effects on soil fertility or water quality. Narrower spacing enhanced total rice yield through higher plant density but reduced individual plant performance. Wider spacing improved individual plant growth yet lowered total yield. Soil nutrient levels (N, P, and K) and organic matter (OM) significantly increased across treatments, with T2 showing the highest enrichment. Water quality parameters (pH, EC, temperature, DO, NO3–, NH3) remained within non-toxic limits. This study suggests that 15×15 cm spacing optimizes rice-fish yields and enhances soil quality without compromising water quality in IRFF systems
Assessing shellfish harvesting and stakeholder perspectives on trade in Bangladesh’s largest wetland
Full text linkThe trade of freshwater shellfish is growing but has received insufficient attention from researchers. In this study, we examined various aspects of shellfish harvesting (catch amount and composition, socio-economic profiles of shellfish collectors, distribution channels and perceptions of major stakeholder groups) over a six-month period (October 2023 to March 2024) in the largest wetland of Bangladesh, the Chalan Beel. The daily shellfish catch was higher during the low-water period (October – December; 10.7 ± 3.3 kg person–1) than during the dry period (January – March; 0.6 ± 0.2 kg person–1) (t-test: t = –32.4, p < 0.001). Catch composition varied significantly across groups (ANOVA: F = 10823, p < 0.001). Freshwater snails (primarily Pila globosa) contributed the most (70.1%) to the total catch, followed by mussels (primarily Lamellidens marginalis; 19.7%) and crab (Cancer pagurus; 10.2%). Three key actor groups involved in shellfish distribution were crab collectors, traders and consumers. Most collectors (65%), traders (54%) and consumers (89%) disagreed that shellfish are an important component of the aquatic environment. All traders and 96% of collectors agreed that shellfish collection and trade are profitable, whereas all consumers maintained a neutral standpoint. All consumers agreed that shellfish are good food, while the majority of collectors (93%) and traders (93%) remained neutral. Additionally, all consumers and most collectors (67%) and traders (73%) supported harvesting shellfish from other aquatic ecosystems. The results of this study are expected to be useful in formulating appropriate policies for wetland and resource management
Phylogeny, genetic diversity and divergence dating of Monodactylus argenteus (Linnaeus, 1758) (Actinopterygii: Monodactylidae) from marine waters of Odisha Coast, Bay of Bengal, India
Full text linkAmong the many different types of aquatic life found in marine ecosystems, fish are the most diverse and commercially important organisms. To support their conservation and management, accurate species identification, genetic, and phylogenetic association studies are crucial. Monodactylus argenteus, the silvery Moony fishes were collected from Gopalpur-on-sea, Odisha Coast of the Bay of Bengal, India and identified as using traditional morpho-taxonomy methods followed by DNA barcoding using cytochrome c oxidase subunit I (COI) gene. Following identification, the phylogeny, genetic diversity, and divergence time of M. argenteus were investigated. The current study looked at the number of variable sites, parsimony informative sites, nucleotide diversity, and haplotype diversity. The 16 sequenced individuals of M. argenteus produced a total of 13 haplotypes, with 11 unique haplotypes and two shared haplotypes. There were 67 polymorphic sites, including 56 parsimony informative sites and 11 singleton variable sites with 72 mutations. Phylogenetic tree was drawn and all the sequences clustered in agreement with their species level taxonomic classification were observed. The divergence time of the M. argenteus species was estimated to be in the late oligocene sub-epoch, about 25.98 mya, using the RelTime maximum likelihood method. The findings of this study serve as noteworthy confirmation of the utility of DNA barcode sequences for tracking diversity of species and also contribute information on the phylogeny, genetic diversity, and divergence dating of M. argenteus
Partial replacement effect of dietary fish meal with blood meal on growth performance, body composition, and haematology of butter catfish Ompok bimaculatus
Full text linkEscalating costs and the constrained supply of fish meal have underscored the imperative to identify alternative, economically viable protein sources for aquafeeds. This study evaluates the feasibility of incorporating blood meal as a partial replacement for fish meal in the diet of butter catfish (Ompok bimaculatus). Five iso-nitrogenous (35.0%) and iso-lipidic (7.0%) diets, designated T0 (control), T5, T10, T15, and T20, were prepared by substituting fish meal protein at 0, 5, 10, 15, and 20% levels with blood meal protein, respectively. Fish groups were assigned to each of the formulated diets in triplicate. Each of the 15 glass aquariums (180 L) was stocked with 50 fish (mean±SD 1.5±0.03 g) and fed with experimental diets for eight weeks. The fish fed the T15 diet achieved the highest weight gain (4.61±0.22 g), percent weight gain (305.30±1.20%), and specific growth rate (1.42±0.21% day–1) compared to fish fed all other diets. The lowest feed conversion ratio (1.85±0.08) was observed in fish fed T10 diet. The highest protein efficiency ratio (1.88±0.02) was also observed in fish fed T15 diet. Replacing fish meal with blood meal positively impacted the haematological profile and whole-body proximate composition. Additionally, the cost of the experimental diets was reduced compared to the control diet. Regression analysis indicated that the optimal replacement level of fish meal protein with blood meal protein ranged from 10.8% to 12.6%. We suggest that blood meal can be effectively used as a partial fish meal substitute in the aquafeed, offering a cost-effective and sustainable alternative
The tooth morphology of juvenile Pacific nurse sharks Ginglymostoma unami (Chondrichthyes: Ginglymostomatidae)
Full text linkNurse sharks (family Ginglymostomatidae) are a small group of sharks that currently consists of four different species. These species are distributed all over the globe, each occupying a specific geographical region. The last described nurse shark species, the Pacific nurse shark (Ginglymostoma unami), is found exclusively on the West coast of America from the Southwest of Baja California and the Gulf of California (Mexico) to Peru. This species was previously synonymized with the Atlantic nurse shark (Ginglymostoma cirratum), but described as separate in 2015. For this reason, some data on tooth morphology, especially that of juvenile individuals, is missing. This study examines a jaw of a juvenile Pacific nurse shark and shows the change in the tooth morphology of this species over the course of its life. In addition, this work compares the tooth morphology of the different nurse shark species and provides an overview of how they can be differentiated
Impacts of palmyrah (Borassus flabellifer) fruit pulp-enriched diets on growth and colouration of swordtail (Xipophorus helleri) and platyfish (Xipophorus maculatus)
Full text linkThe ornamental fish industry urgently needs natural carotenoid sources due to the undesirable effects of synthetic additives. This study examines the effects of an untapped carotenoid source, palmyrah fruit pulp (PFP), on the growth and skin colour of swordtails (Xipophorus helleri) and platies (Xipophorus maculatus). Experimental diets containing 40% crude protein were formulated with varying PFP levels (%) at 0, 3, 6, and 8. A commercial diet was used as a positive control, while a diet without PFP was a negative control. Four-week-old swordtails (n=450) and platies (n=450) were divided into 15 groups for five treatments, and all were kept under the same conditions. The experiment lasted 81 days for the swordtail and 83 days for the platy. The findings show that the 8% PFP diet led to a significant increase in the skin colour in both fish compared to the other treatments. Higher growth performance (ANOVA: p<0.001) was observed in both fish when fed 3, 6, and 8% PFP diets compared to the negative control group; however, no significant difference from the positive control group. All treated groups had a survival rate of over 92%, and weight gains followed strong polynomial relationships (R2>0.98). The study concludes that an 8% PFP-enriched diet effectively influenced skin colour, with TCC levels of 85.59 µg g–1 in swordtails and 80.54 µg g–1 in platies. Furthermore, this diet promotes the growth of swordtails and platies. This diet serves as an adequate substitute for commercial fish feeds in the ornamental fish industry
Social values of angling tourism in the Garo Hills of Meghalaya, North East India: fish farmers’ perspectives
Full text linkAngling tourism is gaining popularity and offers an alternative livelihood opportunity for the fish farmers of the Garo Hills region of Meghalaya, India. This research aims to provide insights into the social value of angling tourism among the fish farmers involved in angling tourism in the area and to identify its determinants. A sample of one hundred fish farmers was selected using snowball sampling from five districts of the Garo Hills, and data were collected using a semi-structured interview schedule. Most farmers considered fisheries a secondary occupation and were sceptical of angling tourism. The multiple stepwise regression analyses revealed that entry fees for daily angling besides competition and secondary occupation negatively impacted social value scores. In contrast, the educational status of fish farmers, annual investment in angling tourism, fish farming experience, total registered anglers annually, and family type positively impacted social value scores. The study confirmed that angling tourism fosters sustainable development within rural communities by nurturing social values and augmenting biodiversity conservation, and economic benefits. Overall, the study provides valuable information on the scope and prospects of angling tourism in leveraging social values and its potential to uplift rural people's social and financial status
Factors affecting export competitiveness of fisheries industry in Malaysia
Full text linkFisheries constitute the most highly traded food commodity internationally owing to its fundamental contribution to global food security and nutrition. Malaysia has been amongst the world’s leading fish producers; however, it has faced a serious fish trade deficit, implicating an absence of export competitiveness in the industry. This study aims to measure the export competitiveness (i.e. Comparative Export Performance index, CEP) of the industry and examine factors affecting CEP by adopting the Autoregressive Distributed Lag (ARDL) approach on the time series data for 2001 – 2022. The major findings revealed that Malaysia recorded an absence of export competitiveness (i.e. CEP < 0) in the international fisheries market, and this issue was significantly affected by fish consumption, followed by foreign income and fisheries production. Fisheries production and foreign income positively affected the CEP in the short-run while fish consumption negatively affected it. In the long-run, fish consumption and foreign income exerted a negative effect on the CEP. The findings of this study are significant for understanding the short- and long-run effects on export competitiveness in Malaysia and can be used for fisheries development strategies
Effects of Streptococcus agalactiae infection and oral florfenicol administration on the hemato-biochemistry, erythrocyte morphology and histopathology of Oreochromis niloticus
Full text linkStreptococcosis is considered one of the most important diseases affecting farmed tilapia, causing severe economic losses. Antimicrobial therapy is the principal control measure applied during outbreaks. This research assessed the efficacy of florfenicol (FFC) when fed at 15 mg kg biomass–1 day–1 for 10 days against Streptococcus agalactiae infection in Oreochromis niloticus in terms of survival, changes in hemato-biochemistry, erythro-morphology, and histoarchitecture of the vital organs. Streptococcus agalactiae was moderately virulent to O. niloticus with a lethal dose (LD50) of 1.26×108 cells fish–1 and sensitive to FFC with a minimal inhibitory concentration of 0.78 μg mL–1. It caused systemic infection in tilapia. FFC therapy reduced bacterium-induced mortality and physiological stress. The histopathological findings indicated significant improvement in the kidney and liver tissues of fish. The erythrocyte morphological alterations noted in the challenged fish were irregularly shaped, elongated, crenated, and teardrop cells, hypochromic erythrocytes, ragged cytoplasmic membranes, hypertrophied nuclei, eccentric nuclei, and vacuolation, all of which were mitigated with FFC therapy. Eventually, FFC therapy improved wound healing, normalized plasma biochemistry, and aided recovery from bacterial infection. This study revealed that the therapeutic dose of FFC was effective against S. agalactiae infection in O. niloticus and lessened the physiological stress