The razorfish genus Iniistius (Labridae) presents taxonomic challenges due to morphological variations across life stages. This study provides a confirmed record and a comprehensive account of the Redblotch razorfish, Iniistius twistii, from the Gulf of Mannar, southeastern coast of India, corroborating a previous preliminary report and solidifying its distribution in Indian waters. Five specimens were collected from demersal trawls off Pamban, Tamil Nadu. Molecular analysis of the COI gene fragment confirmed the species identity, revealing 0
This study reports the length–weight relationships (LWRs) and relative condition factors (Kn) of 15 species of nemipterid fishes (Family: Nemipteridae) collected from two major fish landing centres (Nagapattinam fishing harbour and Cuddalore fishing harbour) along the southern Coromandel Coast of India. A total of 3321 individuals were sampled on a monthly basis from commercial trawl fisheries operating between October 2023 and September 2024. Notably, five new LWR records have been established for Nemipterus virgatus, N. marginatus, N. furcosus, Parascolopsis eriomma, and P. inermis, which had not previously been documented along the Indian coast. The estimated growth coefficient (b) values among the 15 species showed significant variation (P < 0.005) from the expected isometric value of 3, ranging from 2.7355 in N. peronii to 3.3694 in N. randalli. This pattern indicates that most of the studied species display allometric growth. The coefficient of determination (r²) values ranged from 0.8902 (N. randalli) to 0.9915 (Scolopsis vosmeri), with linear regression analyses of length and weight showing high statistical significance (P < 0.001). The Kn values were generally close to or above one, reflecting favourable growth conditions, except in N. marginatus (0.8991) and N. nematophorus (0.9497), which recorded lower condition factors. Overall, these findings provide essential insights into the population health, ecology, and growth dynamics of nemipterid fishes, and they contribute valuable baseline information for fisheries biology, stock assessment, and sustainable management of these resources.
The length-weight relationship (LWR) and various condition factors of the invasive mussel Mytella strigata were investigated in Ennore Creek, Tamil Nadu, Southeast India over twelve months (April, 2025 – March, 2026). A total of 2225 specimens were taken from sampling stations monthly, and recorded in terms of total length (mm) and total weight (g). The allometric exponent b ranged from 1.42 to 2.73 across all months, with all values significantly less than 3.0 (p < 0.05), confirming consistent negative allometric growth throughout the study period. Coefficients of determination R 2 varied from 0.618 to 0.968. Three condition indices were evaluated-the relative condition factor ( K n ) ranged from 0.998 to 1.202, the allometric condition factor ( K a ) from 0.092 to 0.856 and Fulton's condition factor (K f ) from 0.061 to 0.114. Because of the negative allometric growth trend observed in the species. All condition indices showed seasonal variation, with peaks observed in the post-monsoon months (October), and low points during the pre-monsoon months (April), this reflects the importance of monsoon-associated nutrient dynamics and environmental stresses to physiological well-being.
The Japanese spiny dragonet, Callionymus draconis Nakabo, 1977, a member of the subgenus Callionymus (Spinicapitichthys), was previously known only from the eastern Indian Ocean and the western Pacific, with records from southern Japan and Western Australia. This study reports the first record of C. draconis from India, based on a single male specimen (71.0 mm SL) collected from trawl bycatch off Kanyakumari, Tamil Nadu, southeastern Arabian Sea (southernmost port in India). This finding represents a significant westward range extension of approximately 5200 km, establishing the westernmost known limit of the species distribution. Furthermore, the collection depth of 80 to 100 m constitutes the shallowest recorded occurrence for this species, indicating a broader bathymetric range than previously known. This record bridges a major biogeographical gap in the known distribution of C. draconis, enriches the documented marine fish diversity of India, and highlights the importance of bycatch surveys in revealing cryptic marine biodiversity and refining the understanding of Indo-Pacific fish biogeography.
In this study, the effect of hydroxy-selenomethionine (OH-SeMet) and sodium selenite (Na2SeOs) supplementation on growth rates, physiological parameter, and mRNA levels in Nile tilapia (Oreochromis niloticus) was examined. Eleven diets were prepared, consisting of a basal diet devoid of selenium (control) and ten diets supplemented with two selenium sources, OH-SeMet and Na2SeOs, each at 0.25, 0.50, 1.0, 1.5, or 2.0 mg Se/kg. Fish with an initial weight of 6.7 +/- 0.1 g were fed for 60 days in triplicate groups. Growth indices and feed efficiency were significantly increased in selenium fed groups compared to control group. The fish that were fed OH-SeMet at 0.5 mg Se/kg exhibited enhanced somatic growth and nutrient utilization, feed conversion ratio and protein efficiency ratio. Blood parameters (i.e., hemoglobin, hematocrit, red blood cell, white blood cell) showed marked differences with selenium supplementation and the effect was greater with OH-SeMet than Na2SeOs. Serum biochemistry indicated optimized metabolic status, where serum AST (aspartate aminotransferase) and ALT (alanine amino transferase) activities decreased in Se fed groups. While glucose, cholesterol, and triglyceride levels decreased with increasing Se levels, indicating alterations in physiological status. Selenium supplementation enhanced lipase activity with a highest activity observed at 0.5 mg/kg OHSeMet treatment. Antioxidant enzyme (CAT and GPx) activity elevated in OH-SeMet groups and MDA (malondialdehyde) decreased, suggesting an improved antioxidant status. Selenium bioaccumulation increased with OH-SeMet-fed fish, with liver showing higher accumulation than muscle. Intestinal morphology is indicative of improved villus length, width, and crypt depth in Se fed fish. Gene expression analysis exhibited upregulation of growth-related genes (MyoD, myogenin), and antioxidant genes (Nrf2, CAT, GPx) and downregulation of myostatin with selenium supplemented groups, with optimal expression at 0.5 mg/kg OH-SeMet. Results indicate that 0.5 mg/kg OH-SeMet optimizes somatic growth by integrating enhanced digestive enzyme activity with expanded intestinal absorptive surface area (intestinal morphology) and increased antioxidant enzyme activity compared to inorganic selenium without inducing the hepatic stress markers observed at higher inclusion levels.
