The Republic of Guinea, a country located in southwest West Africa, is characterized by an abundant hydrographic network with more than 1165 rivers distributed in 23 river basins, including 9 national and 14 international. The many rivers and watercourses that flow through the region irrigate all the neighbouring countries, making Guinea the “water tower” of West Africa [1] . However, the explorations carried out on all the basins of the Republic of Guinea remain fragmented and old. Despite the work of [2] and [3] , the fish fauna of Guinea’s coastal basins is still imperfectly known. There is a glaring lack of recent data and knowledge about the fish populations. African fish fauna has long been one of the least studied in the world and is not well known in the scientific world. However, this one presents a very great ichthyological diversity [4] and provides a diversified, flexible and resilient livelihood portfolio for some 22 million sub-Saharan fisher-farmers, with half of those living in extreme poverty [5] .

In order to contribute to the knowledge of the diversity, biology and ecology of species in the basins of West Africa in general and Guinea in particular, this study has been initiated whose main objective is to examine once again since its description in 1967 by Paugy, the morphological variation of Synodontis levequei from the Konkouré River basin and describe the relationship between the variables. Their study is highly significant for proper conservation and effective management of fish populations as well as for the scientific community for further research. Indeed, a good knowledge of fish species, through the study of their morphometric characters, meristic, trophic ecology, reproduction and characterization of factors that influence their distribution, is a prerequisite for any measure to conserve fish [6] - [8] . Morphometric study plays a vital role in fish development pattern, habitat conditions, overall health, early life, feeding, fish fatness, development stage, gonad middle age, sexual category, size range, physical condition, and common fish form and maintenance [9] - [13] and can be used for artisanal fishery management and fish resources preservation [14] . For Basuonie et al. [15] , morphological characteristics are of fundamental importance in fishery biology, where it is the major source of information for taxonomic and evolutionary studies. Taxonomic identification is the initial step in the study of a species. Linear regression is a technique to quantify the relationship, visualised in a graph, between two variables. The interpretability of linear regression is one of its greatest strengths. The model’s equation offers clear coefficients that illustrate the influence of each independent variable on the dependent variable, enhancing our understanding of the underlying relationships. Its simplicity is a significant advantage; linear regression is transparent, easy to implement, and serves as a foundational concept for more advanced algorithms.

Moreover, Synodontis levequei Siluriformes, of the Mochokidae family, is a species of upside-down catfish endemic to Guinea, where it occurs in the Konkouré River basin [16] . This species is harvested for human consumption. The main threats to this species are the construction of hydroelectric dams on the upper Konkouré River, deforestation, and farming practices, which are likely causing declines in its overall habitat quality [17] . According to literature and recent data of the International Union for Conservation of Nature and Natural Resources [18] (available at: http://www.iucnredlist.org/ ), this species is assessed as Vulnerable and research is needed into its population dynamics, distribution, threats and ecology, alongside monitoring of population trends.

Synodontis levequei from the Konkouré River (Guinea) has a short and high body with maxillary barbels longer than the head. These findings are similar to Santos et al. [26] , who reported that specimens from the Tropical region had comparatively larger body height, mouth length and maxillary length and smaller values for the other characters (e.g., eye diameter, head height, head length and pectoral fin length). Study revealed significant variation in the morphometrical measurements of Synodontis levequei, particularly Maxillary Barbel Length, Body and Depth and Pelvic Fin Length, which had the highest coefficients of variation. This high variation indicates a large variability among individuals.

The above-mentioned morphometric characteristics were found to be similar to those previously described by Paugy [3] with some differences in the maximum values, e.g., Total Length can reach 23.8 (Fishbase http://fishbase.mnhn.fr/summary/Synodontis-levequei.html ). The scarcity today of large specimens could be due to fishing pressure and the degradation of its habitat (the construction of hydroelectric dams, deforestation and farming practices) as noted by [17] , which are likely causing its vulnerability [18] . Therefore, we suggest that the differences observed in the range of morphological variables could be related to different growth rates under the influence of environmental conditions and available food resources. Additionally, differences in TL could also reflect the degree of exploitation to which the different populations were exposed and non-exhaustive sampling [27] .

As fish morphometric characters usually refer to the measuring of total body length of fish with various other body parts of its anatomy; therefore, accordance to [28] - [30] , a study of linear regression relationships between total body length of fish and several morphometric characters were found to be the best indicator for detecting the growth pattern of fish. In the current study, 5 characters show high values of correlation coefficient with total body length (independent variable), 3 characters show moderate, and 1 shows a low correlation coefficient. Hence, the results of morphometric characters show a positive allometric growth pattern (A+), which reveals the direct relationship between total body length and the growth of various body parts of this species. Similar observations were made by [29] [31] - [33] in morphometric studies of fish. [34] [35] has reported a linear relationship between various body measurements and the total length in other fish species. The value of the coefficient of correlation showed that the relationship between total length and various body measurements of the fish was highly significant (p < 0.01) except the relationship between total length and Maxillary Barbel Length (p > 0.05). Thus, various body characters of S. levequei are dependent variables on the total length of the fish. The closeness of the observation points to the regression line, which reflects that the model predictions are close to the actual value.

As a result of the applied correlation analysis among the morphological characters of Synodontis levequei, a very strong, positive relation between all morphological characters examined in this study was proved, except the correlation between Pelvic Fin Length and Inter Orbital Distance. These findings corroborate the hypothesis described by Devlin et al. [36] , which suggests that, beyond the simple proportionality of interorbital distance and eye size to head size, the eye development in rapidly growing fish becomes decoupled from their somatic growth, often resulting in negative allometry.

It is not possible for us to compare our results with previous studies, as few studies have been conducted on the species, and so far, no reports are available regarding the morphometric analysis. Further investigation may be conducted to obtain comprehensive information.

Despite the limitations of this study, such as the small sample size due to the rarity of the species in catches, we were able to characterize, based on morphometric characters, the species Synodontis levequei endemic to the Republic of Guinea. For each specimen, morphometric approaches are discussed. By examining measurements such as body length, head length, Maxillary Barbel Length, etc., we were able to identify significant differences in size and proportions between the morphological characters.

The results obtained provide basic information for stock management and will enable efficient management strategies of populations of Synodontis levequei specimens endemic to Republic of Guinea freshwaters stock to ensure that their fisheries are sustainable and also to develop appropriate conservation plans.

Further study, particularly on genetic aspects and investigations of the influences of environmental subtleties, is desirable to overlay the mode of saving this species, which is already vulnerable. From the data collected and those in progress, we will study the parameters across the populations, such as growth, mortality, age, and reproductive biology (size at sexual maturity, spawning time, fecundity) for the development of the fishery management systems of the species.

All raw and analysed data of this work are available from the corresponding author, Gildas Djidohokpin, upon request.

The research did not receive specific funding, but was carried out within the employment of the authors, who all contributed.

The authors thank all the fishermen of the Konkouré River for their contribution to the collection of fish samples. The corresponding author contributed to this manuscript during his teaching and research assignment at the University of Nzérékoré in Guinea, so we would like to thank the University of Nzérékoré for providing access to their facilities.