Length-weight relationship of seven Apogonidae species in Lembeh Strait

The weight length relationship (LWR) and condition factors can be an indicator of fish growth and environmental suitability. This study aims to calculate the length-weight relationships and condition factor of six Apogonidae species and compare them with Pterapogon kauderni as an introduced species in the same area and condition. The sample is collected monthly from January to December 2020 using a trap net in the Lembeh Strait area of North Sulawesi. A total of 699 specimens from sampling obtained seven species from the Apogonidae family, with the most specimen belonging to Pterapogon kauderni (33%) and the lowest being Pristicon trimaculatus (4.4%). The results indicated that almost all species exhibited a negative allometric growth pattern with the b value ranging from 2.49 to 2.98, except for Ostorhinchus hartzfeldii resulted in a positive allometric growth pattern (3.24). The condition factor ranges are 0.89-1.32 from all the seven species, with only Apogonichthyoides melas, Pterapogon kauderni, and Ostorhinchus sealei values below one and significantly different from the other group (p<0.05). This result can be caused by various factors and need to be investigated further. This data is useful in establishing a management and monitoring system for Pterapogon kauderni in its introduced area.