Observation of morphometric characteristics in fish Clarias batrachus (Linnaeus, 1758) from Lucknow, Uttar Pradesh

The walking catfish (Clarias batrachus Linnaeus, 1758 ) is an omnivorous bottom feeder, incorporating various food sources in its diet, such as insects, insect larvae, crustaceans, and vegetable matter. It is primarily nocturnal. However, it can adapt to pond conditions and readily switch to a more carnivorous diet. During observation, the main focus is to examine the morphometric relationship of Clarias batrachus for that total ten morphometric characters were measured for each specimen. Notably, a linear relationship was observed between the total length and other morphometric characters. The results highlight a strong correlation between most morphometric parameters and the total length of the catfish. However, it was found that the anal length does not show a significant correlation with the total length.


Introduction
Clarias batrachus (Linnaeus, 1758) one of the most widely distributed catfish found throughout the South East Asia, the Indian subcontinent and Africa as well as in parts of Far East locally known as "Magur". It is distributed in Bangladesh and the Indian states of Odisha, West Bengal, and Assam. Clarias batrachus belongs to the class Actinopterygii and the order Siluriformes. Catfish, including Clarias batrachus, are ray-finned fish and are highly valued in the market for both food and their high price. They are carnivorous freshwater fish with an elongated body. The head is moderately depressed and covered by osseous plates. They have small eyes, a terminal mouth, and four pairs of barbels. The maxillary barbels extend to the middle or end of the pectoral fins, while the mandibular pairs are shorter. The dorsal fin is inserted slightly anterior to the tip of the pectoral fins, and the pectoral spine is strong and serrated on both edges. Its unique ability to survive outside of water for short periods and even move across land has earned it the common name "Walking Catfish." The species has attracted considerable attention from researchers due to its intriguing characteristics, adaptive behaviour, and potential ecological impacts in its native habitats. Clarias batrachus, commonly known as the walking catfish, is a species of freshwater fish belonging to the family Clariidae. This fascinating fish is native to the Indian subcontinent and is widely distributed across various freshwater habitats in the region, including Lucknow, Uttar Pradesh.
The walking catfish gets its name from its unique ability to "walk" on land for short distances, using its pectoral fins, which are adapted to function like legs. This remarkable behaviour allows it to move between water bodies, especially during the monsoon season when temporary water bodies form, providing opportunities for the fish to disperse and find new habitats.
As an important member of the Clariidae family, Clarias batrachus plays a significant role in the local aquatic ecosystems. It is a highly adaptable and resilient species, capable of surviving in various environmental conditions, from slow-moving rivers and ponds to flooded fields and marshes. This adaptability has also contributed to its success as an invasive species in some regions beyond its native range.
The body colour of Clarias batrachus is brownish to green-blue, with a black dorsal side that exhibits a greenish luster. The flanks and belly are pale brown or reddish, often with numerous striking pales to white spots. The dorsal and anal fins display striking red margins. The recorded maximum lengths for this species vary according to different sources. According to Bhuiyan (1964), the maximum length recorded is 23 cm. Rahman (1989 and2005)  Morphometric measurements play a crucial role in identifying and studying fish species. The morphometric study of Clarias batrachus helps in its identification and provides information on its taxonomic status (Ihssen et.al.1981). Identification aims to investigate the relationship between various morphological characters of Clarias batrachus and establish mathematical equations that relate to morphometric relationship. The fish morphometric characters represent one of the major keys for determining their systematic and various morphometric parameters (Kova et.al. 1999). These equations can be used for converting one measurement into another.
The genus Clarias batrachus belongs to a group of air-breathing catfish found in inland waters. Among the 16 Asian species in the genus, Clarias batrachus is one of the most well-studied (Linnaeus,1758). It is widely utilized in aquaculture, appears in the aquarium fish trade, and has been the subject of numerous studies on its behaviour (Ghosh and Pati, 2004).
Clarias batrachus is distributed throughout South and Southeast Asia and is popular for aquaculture within its native range (Hora ,1936;Kottelat, 2001). However, it is also regarded as an invasive species in other Southeast Asian countries. It has been introduced in many parts of the world for aquaculture and as a pet fish (Talwar and Jhingran, 1991).
Fish exhibit greater morphological variation within populations and between species compared to other vertebrates. They are highly sensitive to environmental changes and can quickly adapt by changing their morphometries. Morphometric characters are important for correctly identifying fish species and understanding their habitat and ecological criteria in different aquatic environments (Jayaram, 1999). The complete set of measurements used to describe According to Strauss and Bond (1990), a form is a set of morphometric characters that encompass measurable features such as size, shape, proportions, angles, and other quantitative parameters for analysis.

Study Area
A total of 20 specimens collected from various fish markets, including Khurram Nagar fish market, Tadikhana fish market, Samples were collected by collecting specimens of different sizes from these markets. The collected fish specimens were preserved in a 10% formalin solution and brought to the laboratory for further analysis.

Morphometric and other analysis of fish body
The identification of the fish species was primarily based on external features such as the mouth, body shape, length, depth, and width. Standard taxonomic keys, such as those provided by Talwar and Jhingran (1991) and Jayaram (1999), were used for the scientific identification of the fish. The morphometric measurements of Clarias batrachus were taken using relative units such as centimeters (CM) for length measurements. The morphometric characters that were

Statistical analysis
The relationship between the total fish length and the morphometric characters was estimated using the following formula Y = a + bX Where: Y = morphological characters, X = total fish length, a, b = constants Overall, these studies highlight the positive correlations between standard length and various morphometric characters in different fish species, indicating the importance of standard length as a reliable measure in assessing fish growth and size-related characteristics.

Conclusion
Present study provides valuable insights into the morphometric characteristics and their correlation in Clarias batrachus, a freshwater catfish species. The analysis of morphometric characters in Clarias batrachus revealed a minor degree of influence from the surrounding environment. A total of ten characters were examined, and it was observed that these characters were primarily determined by genetic factors. However, there was also a minor influence from the environment on these characters.
The high values of correlation coefficient indicated a strong positive relationship between the morphometric parameters and total length, suggesting that these parameters increase proportionally with total length. This type of study is crucial for effective species management as it can be used to assess the well-being of individuals and identify potential differences between separate populations of the same species.