Length-Weight Relationship and Morphometric Analysis of Crossocheilus diplochilus (Heckel, 1838) from the Dal Lake of Kashmir Himalaya

Background and Objective: Crossocheilus diplochilus ( C. diplochilus ) locally known as “Tether” is an endemic fish of Kashmir Valley. The length-weight relationship is one of the standard methods that yield authentic biological information and is of great importance in fishery assessments. Morphometric studies have been the primary source for taxonomic and evolutionary studies. To accurately manage fish populations, it is necessary to estimate their growth rates through the study of morphometric traits. This study was conducted in order to obtain information about the somatic growth of fish. Materials and Methods: Morphometric characters were measured by using fish measuring board and Vernier Calipers for accuracy to the nearest millimeter. The weight of the fish was measured using an electronic weighing balance. Results: The specimens examined in this study ranged in size from 81.9 to 119.7 mm in length and 5-13.5 g in weight. Length-weight relationship of Crossocheilus diplochilus revealed negative allometric growth with b value <3. The Log W = -4.8819+2.9072 Log L is the calculated and expressed form of the length-weight relationship equation. Standard length and fork length had the highest correlations with total length, at 0.853 and 0.842, respectively. Correlation analysis revealed that all morphometric characters changed proportionally as total length increased. Conclusion: The findings of this study, offer the fundamental details on the morphometric traits and length-weight parameters of Dal Lake’s Crossocheilus diplochilus , which may aid in the straightforward identification of the fish species and could be used to study fish population dynamics and growth patterns.


INTRODUCTION
The Dal Lake is located at an elevation of 1584 m above sea level between 34°5' and 34°6'N latitude and 74°8' and 74°12'E longitude 1 . Since ancient times, the lake, sometimes referred to as the "liquid heart" of Srinagar City, has been an indispensable fishery resource for the people of the valley, particularly Srinagar City 2 . Many native and exotic fish species, including schizothoracines, carps and trouts, as well as a number of small fish species, such as Triplophysa, Crossocheilus and Gambusia, have habitats in these water bodies 3,4 . The genus Crossocheilus belongs to the family Cyprinidae, which includes various carps and minnows. This fish can be found in a variety of habitats, but it is most frequently found in streams, reservoirs and rivers with swift currents and rocky bottoms 5 . Due to its small size, this fish has little commercial significance. It contributes significantly to the aquatic food chain and preserves ecological balance because it is preyed upon by large carnivorous fish. The fish has been designated as least concerned (LC) under the IUCN (2010) criteria. The freshwater benthopelagic fish Crossocheilus diplochilus (Heckel), also known as Kashmir latia, is widely distributed in Kashmiri waters. The fish grows to a maximum length of about 10-17 cm 6,7 . This fish can be found in a variety of habitats, but it typically prefers lakes and the banks of major rivers, it does not migrate up to cold water tributaries. It typically consumes epilithic growth, such as diatoms, filamentous algae and organic debris. This species has 36-38 lateral line scales, two pairs of barbells and an inferior mouth. Since this fish serves as a crucial food source for many commercially significant food fish species, studies of this species are required. Shape, size, meristic counts and morphological measurements provide information that is helpful for taxonomic status 8 . In comparison to other vertebrates, fish typically exhibit greater variation in morphological traits both within and between populations and they are more highly susceptible to morphological changes brought on by the environment individual well-being and the potential differences between different unit stocks of the same species can be evaluated using the morphometric relationships between different fish body parts 9,10 . Fish are very sensitive to changes in their environment and they quickly adjust by changing the necessary morphometrics 11 . For taxonomic work, knowledge of fish morphometric measurements and research into their statistical relationships are crucial 12 . Morphometric characters can be used to identify the traits that are genetically controlled and those that are influenced by the environment 13,14 . Based on the difference in range, the various morphometric characters have been, numerous morphometric characteristics have been classified as genetically (limited range), intermediate (moderate range) and environmentally (wide range) regulated character 15 . To manage a fishery effectively, it is necessary to understand the relationship between length and weight 16 . The ability to estimate the average weight of fish in a given length group, evaluate the well-beingof individuals and identify potential variations between separate unit stocks of the same species make this relationship crucial to fisheries biology 17 . The standard method for quantifying growth in fisheries is to fit statistical models to data. Additionally, fisheries scientists can transform growth-in-length equations into growth-in-weight stock assessment models by using length-weight relationships. The goal of the current investigation was to gather information regarding the length weight and morphometric characteristics of the fish Crossocheilus diplochilus (Hamilton-Buchanan) found in Dal Lake, Srinagar, India.

MATERIALS AND METHODS
Collection of fish sample: The present study was conducted from August, 2022 to February, 2023. From the Dal Lake, a total of 40 Crossocheilus diplochilus specimens were obtained. A simple random sample that was representative of each length group was taken. The collected samples were brought to the Fish Genetics and Biotechnology Laboratory, Faculty of Fisheries, SKUAST-K in ice boxesfor Biological Analysis.

Length-weight relationship:
The primary objective of length-weight data analysis is to mathematically describe the relationship between length and weight so that one can be converted to the other 18 . Additionally, it calculates a fish's deviation from its expected weight for its length. The conventional formula W = aLb, as described by Le Cren ED 18 , was used to perform the calculations. Before the calculations, the equation (above mentioned) and data were logarithmically translated. As a result, the formula obtains Log W = log a+b log L. Where W and L represent total body weight in grams and length in millimeters, respectively and a and b are the functional regression coefficients between W and L.
Morphometric analysis: By using fish measuring board and Vernier Calipers, morphometric characters were measured for accuracy to the nearest millimeter as described by various authors. Morphometric characters were measured by using fish measuring board and Vernier Calipers for accuracy to the nearest millimeter as described by various scientists [19][20][21][22] . The scatter plot for this LWR is given in Fig. 1.
It is a universal truth that as an animal's body length increases, so does its ability to grow 23 . Therefore, it can be inferred that length and growth are related. If the fish maintains its shape and its specific gravity stays constant, it will exhibit isometric growth and the value of the exponent 'b' will be 3.0 precisely 24 . If the value is greater than 3.0 it indicated that the fish become heavier for a given length and less than 3.0 indicated that the opposite is true. In the present study, the b value was recorded at 2.9072, which indicateda negative allometric growth pattern. In other words, as length increases, C. diplochilius becomes less rotund (slender). Similar results were observed by other researchers in C. diplochilius 3,25 . Labeo dyocheilus 26 , Cyprinus carpio communis and Ctenophyryngodon idella 27 and Rasbora dani conius 28 have all  Table 1.  Table 2 illustrated the values of the constants "a" and "b" and the correlation "R 2 " for the different morphometric relationships.
Fish morphometric analysis has been used extensively in fish identification 30  The current study offers fundamental knowledge regarding the differentiation of C. diplochilus populations using morphometric parameters and recommends that morphometric variations seen in this species can be taken into account in its biodiversity pattern as well as be used as a first step towards fisheries

CONCLUSION
The results generated in the present study will provide baseline data on length-weight relationship and the findings of this study will offer baseline data on the length-weight relationship and morphometry of C. diplochilus, facilitating easier identification and contributing to the development of a conservation plan for the natural populations of C. diplochilus in Dal Lake. According to the findings of the current study, this fish exhibits negative allometric growth in accordance with the cube law. Total length has been found to positively correlate with a number of morphometric parameters. For more accurate results, a combined approach combining morphometry, genetics and other biological indicators (such as the growth pattern of scales and otoliths) must be taken into account.

SIGNIFICANCE STATEMENT
Morphometric differences among stocks of a species are recognized as an important method for evaluating the population structure and as a basis for identifying stocks. Morphometric measurements are widely used to identify differences between fish populations and such types of studies in this group of species are scanty. The manuscript will through light on the morphometric and meristic aspects of this fish species.