Altered reproductive behaviour in Siamese fighting fish (Betta splendens) after exposure to different levels of turbidity derived from palm oil mill effluent

Increased turbidity due to Palm Oil Mill Effluent (POME) contamination has been reported in several water bodies. However, the impact of POME-derived turbidity on the reproductive behaviour of fish is still unexplored. Hence, this study was aimed to investigate the alteration in reproductive behavior of siamese fighting fish (Betta splendens) after exposure to different levels of turbidity derived from POME. In total, 12 sexually mature pairs of siamese fighting fish were exposed to the different levels of turbidity, namely <1 NTU (control), 20 NTU (Treatment A), 40 NTU (Treatment B), and 60 NTU (Treatment C) with three replicates. Reproductive performance (total released egg, relative weight of released eggs, and nest area) and behaviour parameters (fin spreads, tail beats, chasing, leads, circling, and copulation) were measured. Results showed that an increase in turbidity (>40 NTU) due to POME contamination significantly decreased total released egg but did not have significant impact on relative weight of released eggs and nest area. Decreased total released eggs was occurred due to several alterations in the reproductive behaviour of siamese fighting fish during both the premating and mating stages. Duration of premating and mating stage was significantly decreased at turbidity level of 60 NTU. During premating stage, the number and average time of fin spreads behaviour at turbidity level of 60 NTU were significantly increased. In addition to, the number of chasing behaviour was significantly decreased with increasing turbidity levels. Furthermore, several alterations in reproductive behavior was also observed in mating stage, including increasing number and average time of lead, copulation interval, number of tail beat, average time of lead, and average time of circlings, followed by decreasing number of leads and number of circlings. In addition to, number of copulation and eggs per copulation showed an increasing and decreasing pattern at turbidity level of 40 and 60 NTU, respectively. The study suggests that reproductive behavior of fish might consider as alternative approach to support POME remediation management, mainly for turbidity parameters.