The Jekyll and Hyde fish: Phenotype as a determinant of the invasion potential of Polypterus senegalus Cuvier, 1829

Abstract

Biological invasions lead to considerable environmental and socioeconomic losses globally. For freshwater fish, the invasion potential of different phenotypes of the same species is influenced by various behavioural and physiological traits. In this study, we compared traits related to invasion potential between albino and pigmented grey bichir (Polypterus senegalus). This species, which is native to Africa, is widely traded as an ornamental animal worldwide. In Indonesia, established populations of both phenotypes have been found. The grey bichir poses a potential invasion risk due to its high adaptability and unique physiological traits, such as its ability to perform terrestrial locomotion, its well-developed lungs and its ability to breathe air. Four experiments were conducted to assess the behaviours of the albino and pigmented phenotypes in novel environments and their stress resistance, daily activity patterns, and feeding adaptability. The increased ventilatory rates and locomotor activity among the albino phenotype suggest higher stress levels compared with those of the pigmented phenotype, potentially making them less capable of dispersing to new localities. However, owing to their greater adaptability to food changes and superior ability to find shelter, the albino phenotype could still pose an invasion risk. On the basis of these findings, the cultivation and trade of albino bichir in aquaculture cannot be recommended because of the potential environmental risks, which may exceed those posed by their pigmented counterparts. These insights improve our understanding of fish invasion dynamics and support the development of regulatory measures in aquaculture.