Journal of Fisheries

Comparison between Indian spinach production in aquaponics utilizing fish wastewater and hydroponics biogas slurry solution

2025-12-11T20:59:02+00:00

The experiment compared Indian spinach production in aquaponics utilizing fish wastewater and hydroponics with biogas slurry solution. The aquaponics system involved 60 juvenile tilapias, released into a 750 L tank with an average initial length and weight of 14.41 ± 0.66 cm and 49.81 ± 4.29 g, respectively. The fish were fed commercial pelleted feed twice daily and maintained suitable water quality parameters, including pH, temperature, and DO, within the required range. The hydroponics system used biogas slurry as nutrient media. In each system, 3 plant beds were used, and 4 Indian spinach plants were planted in each bed. Physical parameters of water indicated that the aquaponics system had higher levels of EC, HCO₃, CO₃, Total-N, potassium, sulphur, and sodium than the hydroponics system. After 90 days, aquaponics had the largest plant weight (82.05 ± 23.31 g), with significantly higher levels of nitrogen, potassium, and sulphur content (by 5.54%, 3.10%, and 0.61% respectively) in leaves was found in aquaponics, while the phosphorus (0.85%) was higher in hydroponics. The yield of Indian spinach was higher in aquaponics (2.88 kg m^–2) than in hydroponics (1.52 kg m^–2). Length gain of experimental fish in aquaponics was 10.54 ± 1.51 cm, weight gain 112.71 ± 21.75 g, with a percent weight gain of 227.23 ± 42.98, specific growth rate of 1.4 ± 0.16% day^–1, which was normal. The study concluded that wastes from tilapia aquaponics are more suitable for Indian spinach cultivation than low-cost biogas slurry hydroponics.

First record of the toxic shadow goby Yongeichthys nebulosus (Gobiidae: Gobiinae) from West Bengal, eastern India

2025-12-10T06:59:48+00:00

Herein, the first specimen-based record of Yongeichthys nebulosus (Forsskål, 1775) (Gobiidae) is reported from West Bengal, eastern India. Three individuals were collected from mangrove-associated waters in the Indian Sundarbans, one of which was preserved as a voucher specimen at the Zoological Survey of India. This record represents a north-eastward range extension for the species, which has previously been recorded from other parts of the Indian coast, including the neighbouring state of Odisha. Morphological and meristic features of the voucher specimen are consistent with published diagnoses. The discovery highlights the importance of specimen-based documentation for accurately recording species distributions and emphasises the need for sustained biodiversity monitoring in estuarine habitats.

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

2025-12-10T07:00:04+00:00

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

2025-12-10T07:00:22+00:00

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

2025-12-10T07:00:41+00:00

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.