Invasion and Expansion of Monogenean Parasites in India: Emerging Threats to Fish Biodiversity and Health

The invasion of non-native parasitic fauna in India has steadily increased alongside the introduction of their exotic hosts. The expansion of non-native monogeneans in Indian waters has been largely facilitated by human-mediated transfers of these hosts, which play a major role in their establishment in new localities. Parasites of exotic hosts may switch to native species, leading to transmission that can adversely affect India’s native fish diversity.

However, limited attention has been given by Indian researchers to non-native monogenean parasites, as no such species had been documented previously. In recent years, growing interest in biological invasions has encouraged biologists to investigate the role of non-native parasites and the risks associated with them. Based on recent occurrences of monogeneans in India, it is evident that these parasites are co-introduced with their exotic hosts and readily establish themselves in new environments due to their simple, single-host life cycle.

The aquarium fish trade is a major pathway enabling the continual introduction and spread of monogenean parasites in India. The presence of non-native monogenean fauna indicates a lack of effective national guidelines for the ornamental fish trade. Therefore, proper surveillance and disease diagnostic measures should be implemented prior to the introduction of exotic fishes. Additionally, existing Indian guidelines for the import of ornamental species should be revised to safeguard both aquaculture industries and the aquatic environment.

The objective of this study is to assess the extent of non-native monogenean parasite invasions in Indian waters and to analyze the associated risks to native fish species.