IMMUNOGENETIC INSIGHTS AND CONSERVATION OF THE ENDEMIC LEMPUK FISH (GOBIIFORMES: Gobiopterus)

The health and conservation of the endemic lempuk fish (Gobiopterus sp.) are closely linked to their genetic diversity and immunological function. Assessing immune gene expression offers a robust indicator of fish health and environmental stress. This study examines the morphological characteristics, immune gene activity, and genetic variation of lempuk fish from Ranu Grati, East Java, Indonesia. Males had larger bodies and longer dorsal fins than females, which were shorter and stockier. Expression of immune genes (TNF-α, IL-6, IFN-γ) was quantified using RT-qPCR, while mitochondrial COI sequences were analyzed to determine genetic relationships. TNF-α was markedly upregulated, suggesting a strong pro-inflammatory response to environmental or pathogenic stimuli. COI analyses revealed moderate genetic divergence between East Javan and adjacent populations, with a close affinity to Malaysian Gobiopterus and clear separation from Australian species. Preserving genetic variation is essential for resilience against environmental stressors, and is necessary for the conservation of this endemic species.