Journal of Fisheries

Evaluation of silkworm pupa meal on growth, body indices, digestive enzymes and histopathology of Cirrhinus mrigala fingerlings

2025-06-20T05:29:06+00:00

The world's growing population needs food, and aquaculture; a fast growing food producing sector, provides it. Fish meal (FM) is a major feed source in the aquaculture industry, but its low profitability and scarcity have prompted a quest for high-protein substitutes. Because silkworm pupa meal is inexpensive and has a high protein (50–60%) concentration, it was utilized as a substitute for fish feed. The goal of the current study was to determine the ideal proportion of silkworm pupa meal (SPM) to substitute for FM while creating an affordable feed for Cirrhinus mrigala fingerlings (average total length: 6 cm; average weight: 8 g). The fingerlings were fed six test diets (0, 20, 40, 60, 80, and 100%) at a rate of 4% of their live wet body weight twice a day. Diets contained chromium oxide as an inert marker. The feeding trial lasted for ninety days. The fingerlings' weight was measured every 14 days to calculate growth metrics (weight gain percentage, FCR, and SGR). Following the conclusion of the trial, intestinal histology, digestive enzyme function, and body indices were examined. Highest growth rate (WG%: 333%, SGR: 1.64, FCR: 1.26, CF: 1.50) and best body indices (hepatosomatic index: 1.95, viscerosomatic index: 6.43) values were observed at 40% replacement of FM. Intestinal histological analysis and digestive enzyme activity demonstrated that SPM can be readily substituted up to 40% without affecting the general performance of C. mrigala fingerlings and aid in creating an economical and environmentally friendly diet.

Checklist of Ichthyofaunal diversity of Nagaland, India

2025-06-20T05:29:20+00:00

The present review presents a checklist with an aim to review and summarize the results of the systematic researches on the freshwater resources including various rivers and aquatic resources of the north eastern state of Nagaland, India. The need of such a review is of utmost importance as systematic status of many of the species has changed, and reorganization and updating of the published information has become essential for future ichthyofaunal studies in the state. The total confirmed fish species of the state of Nagaland comprise of 219 species belonging to 31 families. The most diverse family is Cyprinidae with 90 species (41.09%), followed by Sisoridae with 22 species (10.04%), Nemacheilidae with 16 species (7.3%), Bagridae with 11 species (5.02%) while the remaining 26 families account for rest of the species in the list. This paper will certainly help in making appropriate conservation and management planning for fisheries in all the rivers of Nagaland and would also be helpful in looking at the various degenerative reasons for population decline of fishes.

Vietnam’s capture fisheries labor shortage explored: difficulties and responses

2025-06-20T05:29:33+00:00

The fishing industry plays an essential role in Vietnam’s socioeconomic development, providing jobs to millions of workers. In recent years, fishing labor shortages have occurred on many fishing vessels in all capture fisheries, including small-scale and larger-scale fisheries in Vietnam. However, information pertaining to Vietnam’s fishing laborers has been limited for many years. In this study, a combination of secondary data methods and analysis of survey interviews with fishers who are fishing vessels’ owners and fisheries authorities in some key coastal provinces was used to answer the following questions: i) what are the difficulties in recruiting fishing labor in Vietnam’s capture fisheries? ii) How do fishing vessel owners respond to fishing labor’s shortages? Study results show many difficulties in crew labor issues in Vietnam in terms of finding crew members and maintaining minimum conditions for the number of workers on fishing vessels. Many reasons are found that cause the shortage of fishing laborers working on vessels. The owners of the fishing vessel have various ways to address this situation, including forcing fishing vessels to lie ashore or even go fishing in the case of labor shortage, switching to alternatives that require fewer human resources, actively seeking labor in other areas such as remote and mountainous areas, and increasing the share rate and deposit for fishing vessels fishing mates. Several solutions are proposed according to the results to overcome the labor shortage in Vietnam's capture fisheries.

Impact of high intensity ultrasound on the quality and preservation period of blue shrimp (Litopenaeus stylirostris) muscle

2025-06-20T05:29:46+00:00

Due to the limited shelf life of aquatic products, the use of advanced technologies to extend their freshness has become more popular recently. This study aimed to assess the impact of high-intensity ultrasound (HIU) on the quality of blue shrimp (Litopenaeus stylirostris) tails during 20 days of ice storage. Shrimp samples were treated at 70% amplitude for 0 (C), 30 (T1), 60 (T2), and 90 (T3) minutes. Key quality parameters were analyzed every 5-day. The initial total bacterial count (TBC) was 2.02 log CFU g^–1, increasing to 6.09 (C), 5.32 (T1), 5.01 (T2), and 5.34 (T3) at the end of storage, with the control samples exceeding the acceptability limit. In terms of color, the initial L* value was 52.96, increasing to 62.96, 57.69, 57.94, and 57.78 for C, T1, T2, and T3, respectively. No significant differences were observed among treatments in pH (ranging from 7.22 to 8.33), shear force (from 15.40 to 18.50 N), water-holding capacity (from 93.02 to 98.23%), TVB-N (from 24.11 to 31.61 mg 100g^–1), or non-protein nitrogen (from 0.78 to 0.48%). Likewise, SDS-PAGE profiles showed no visible protein degradation. These results indicate that HIU, particularly at 60 minutes, can extend shelf life by delaying microbial growth and preserving color, without adversely affecting the physicochemical or structural properties of the muscle.

Anesthetic efficacy of Mentha piperita and Mentha spicata essential oils on rainbow trout (Oncorhynchus mykiss)

2025-06-20T05:29:59+00:00

In 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.