Sexual Dimorphism of Ambigous Hulu'u Fish (Giuris sp. Limboto) from Limboto Lake, North Sulawesi.

Intraspecific sexual dimorphism between males and females is tied to sexual selection, such as body features and color patterns. Sexual selection pressure in the genus Giuris may occur in either or both sexes. The present study aimed to analyze the sexual dimorphism of Hulu'u fish (Giuris sp. Limboto) from Limboto Lake, Gorontalo Province, North Sulawesi. 272 individuals of Giuris sp. from Lake Limboto, were used with a male to female ratio of 1:1. The mean total length (TL) of male and female fish was 11.5± 2.1 and 12.2± 2.8cm, respectively. A total of 17 morphometric characters were analyzed using the morphometric truss method (dividing using TL) and analyzed by Z-test. Characters with significant differences between males and females were then analyzed using principal component analysis (PCA). The study found that male fish have longer fin sizes than females, including the length of the first dorsal, pectoral, pelvic, anal and caudal fin. In addition, male fish have longer heads than female fish. PCA analysis of the first principal component (C1) consisted of several characteristics: the length of the first dorsal, pectoral, and caudal fin length. The characteristics of head length, pelvic fin length, and anal fin length are associated with the second principal component (C2). The first and second main components could explain 78.3% of the data diversity. Furthermore, the male individuals had a conical genital papillae shape, contrasting with female individuals with bulbous genital papillae shape. In conclusion, males and females of Giuris sp. from Lake Limboto can be distinguished by their fins, heads, and papillae. [ABSTRACT FROM AUTHOR]