Effect of lighting on heart rate performance of Eel ( Anguilla bicolor )

Eels ( Anguilla bicolor ) are catadromous fish with a complex life cycle, in which the elver stage represents a critical transitional phase from marine to freshwater environments. Environmental factors such as light significantly influence eel physiology, migratory behavior, and metabolic activity. This study evaluated the effects of different light spectra on the cardiac performance of elver-stage eels using a non-invasive electrocardiogram (ECG) technique. The experiment was conducted at the Fish Behavior Laboratory, Faculty of Fisheries and Marine Sciences, IPB University, from January to May 2024. Three lighting treatments were applied: blue light (~450 nm), full-spectrum white light, and a control condition without additional lighting. A Completely Randomized Design (CRD) was employed with three replicates per treatment. Results indicated that white light significantly increased heart rate (69.6 ± 0.92 bpm) compared to blue light (46.6 ± 0.90 bpm) and control conditions (48.6–51.2 bpm) (P < 0.05), suggesting a heightened stress response under white light exposure. In contrast, blue light maintained more stable cardiac activity, indicating reduced physiological stress. These findings are relevant for the optimization of eel fishing techniques, conservation, and fish welfare management.