Journal of Fisheries

The effect of different dietary protein levels on the water quality and reproductive performance of Nile tilapia (Oreochromis niloticus) broodstock in biofloc system

2025-09-09T10:27:15+00:00

This 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.

Partial replacement effect of dietary fish meal with blood meal on growth performance, body composition, and haematology of butter catfish Ompok bimaculatus

2025-09-09T06:24:35+00:00

Escalating 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.

Current status of blood cockle (Tegillarca granosa) aquaculture off Myeik City, Myanmar

2025-09-08T06:20:52+00:00

Blood cockle aquaculture has played a vital role in the local economy around Myeik City, a major fishing hub in southern Myanmar, in recent years. This study aimed to assess the current state of aquaculture grounds and to contribute to the development of sustainable blood cockle farming. To determine the status of sowing aquaculture grounds, the main fishing sites were identified through boat-based surveys and interviews with local fishermen. Environmental characteristics of these areas were estimated using satellite imagery, along with weather and sea condition data. Additionally, shell length and whole weight of blood cockles purchased from a market in Myeik City were measured, and their digestive tube contents were examined. These results revealed that farming grounds were located around coves and creeks on small islands along the east coast of Kadan Island. These areas were characterised by high turbidity, with salinity remaining stable year-round at over 20 PSU. The annual chlorophyll-a concentration, approximately 4 μg L^–1, indicated a consistent presence of phytoplankton, which was also confirmed by the digestive content analysis. However, compared to data on blood cockles from other regions reported in related studies, those collected after the rainy season were noticeably lighter in weight, indicating a leaner condition. These findings suggested that alternating the use of offshore and coastal aquaculture grounds according to the rainy and dry seasons may enhance farming efficiency and realise sustainable aquaculture practices.

Factors affecting export competitiveness of fisheries industry in Malaysia

2025-09-08T06:21:42+00:00

Fisheries 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.

Phylogeny, genetic diversity and divergence dating of Monodactylus argenteus (Linnaeus, 1758) (Actinopterygii: Monodactylidae) from marine waters of Odisha Coast, Bay of Bengal, India

2025-09-08T06:22:25+00:00

Among 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.