Journal of Fisheries

Effects of dietary protein on growth and nutrient utilization in ornamental koi fish Cyprinus rubrofuscus (Lacepede, 1803)

Waqas Ahmad — 2025-11-20

Ornamental fish farming is an expanding sector and determining the ideal dietary protein for fish growth is crucial for the success of fish farming in developing countries. In this study, the impact of varying dietary protein (DP) levels (25, 30, 35, 40, 45 and 50%) on the growth and feed conversion ratio (FCR) of koi fish (Cyprinus rubrofuscus) were assessed. The fish fed twice daily for 90 days at a rate of 5% of their body weight and growth parameters and FCR measured every 15 days. Results revealed that the highest weight gain (170.98 g) observed with the 35% DP diet (D-3), while the lowest gain (103.98 g) occurred with the 45% DP diet (D-5). The 35% DP diet also produced the specific growth rate (0.59±0.10), protein efficiency ratio (PER) 2.27±0.27 and feed efficiency percentage (FE%) 60.57±4.40, all of which were significantly higher (p < 0.05) than those from the other diets. The best FCR value of 1.65±0.12 was also found in the 35% DP diet (D-3), which was significantly lower (p < 0.05) than the others. Nutritionally, moisture and ash content was significantly lower (p < 0.05) in D-3 as compared to other diets. Additionally, dietary protein levels had a significant effect (p < 0.05) on final weight, specific growth rate, protein efficiency ratio and protein feed of C. rubrofuscus. These findings offer important insights into the optimal dietary protein level for C. rubrofuscus, which could help improve the commercial success of ornamental fish farming.

First record of the symbiotic crab Harrovia elegans De Man, 1887 from west coast of India

Pradip Kachhiya — 2025-11-19

The 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.

Drying and smoking of fish: nutritional significance, safety concerns and emerging technologies for food security

Nidhi Singh Sengar — 2025-11-17

The 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.

Assessing shellfish harvesting and stakeholder perspectives on trade in Bangladesh’s largest wetland

Goutam Singha — 2025-11-10

The 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.

Optimising feed management for green tiger shrimp (Penaeus semisulcatus) in a biofloc system: impacts on growth performance, body composition and antioxidant activities

Mohammad Hossein Khanjani — 2025-10-30

This study conducted over a 45-day period examined how different feeding strategies affect green tiger shrimp (Penaeus semisulcatus) development in biofloc aquaculture systems. The investigation focused on juvenile shrimp with an initial mean weight 2.85 ± 0.22 g, distributed across various experimental conditions. Five distinct treatment groups were considered, each consisting of tanks with a volume of 150 L of filtered seawater. Each tank was stocked with 53 shrimp, maintaining a stocking density of ~1 g L^–1. Four groups utilised biofloc technology (BFT) with varying feeding levels: 0% (BFT0), 2% (BFT2), 4% (BFT4) and 6% (BFT6) of body weight per day. One additional group served as control, using a clear water system with feeding level of 6% (CW6) body weight daily. The BFT systems successfully maintained optimal water parameters despite minimal water exchange requirements. Performance metrics indicated that shrimp in the BFT4 and BFT6 groups achieved higher biomass production and survival rates. Biochemical analyses demonstrated enhanced nutritional profiles (protein, lipid and ash) in BFT-treated specimens. Antioxidant enzyme activity was significantly elevated in BFT systems, indicating improved overall health status. Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities were significantly higher in BFT groups than control. These findings suggest that feeding juvenile green tiger shrimp at 4% body weight within a BFT system represents an optimal strategy, achieving balanced growth performance while maintaining superior water quality and enhanced animal health indicators without compromising survival rates or body composition.