Journal of Fisheries

Dietary emamectin benzoate alters the gill and spleen histoarchitecture of monosex Oreochromis niloticus fry

2025-07-08T05:39:18+00:00

Oral administration of the antiparasitic veterinary drug emamectin benzoate is recommended to control infectious ectoparasites, whose biosafety and effect on vital organs are unknown in several fish species. This study evaluated the influence of dietary emamectin benzoate on the histopathology of hitherto understudied organs, such as gills and spleen of all-male Oreochromis niloticus fry at the recommended dose of 50 µg and an overdose of 500 µg kg body weight^–1 day^–1 for 7 days. The fry recorded dose-dependent discrepancies in feed intake, survival and biomass. Histologically, noticeable pathological changes in the gill and spleen tissues were documented in both groups. The pathological alterations in the fry fed the recommended dose and increased severity in the overdosed groups indicated the toxic nature of emamectin benzoate and signified exercising caution during its application in tropical aquaculture.

Assessment of reproductive biology of Garra langlungensis (Teleostei: Cyprinidae) from the Langlung River, Nagaland, India

2025-07-08T05:39:30+00:00

The stone sucker, Garra langlungensis Ezung, Shaingningam & Pankaj, 2021, is confined to the Langlung River, near Zutovi village in Dimapur district of Nagaland, India. This endemic fish is a common food item among the local people. There is scarce information available on this species. Despite its rising exploitation, the lack of data could contribute to its decline and potential loss. The present study involved analysis of 213 specimens from the Langlung River, collected monthly over a period of one year, to determine the sex ratio, gonadosomatic Index (GSI), and fecundity. The sex ratio of males to females was 1:0.43 (deviation from the expected 1:1 ratio), showing a male-dominated population. The monthly assessment of GSI indicated that G. langlungensis breed once a year, with maximum GSI values of 8.1 (male) and 11.5 (female) in April and a short breeding season extending from February to May. Fecundity, based on data from 16 mature fish specimens, was the highest (844 eggs) in 77.9 mm TL (0.56 g) and the lowest (319 eggs) in 55.2 mm TL specimen (0.23 g). A significant correlation between fecundity and ovary weight (r = 0.915) was recorded. This study provides insights into the sex ratio, GSI, and fecundity of G. langlungensis, which facilitate the identification of fish stocks in their natural habitats and the development of appropriate conservation measures.

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

2025-07-08T05:39:44+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

2025-07-08T05:39:57+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

2025-07-08T05:40:09+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.