ABSTRACT
Fish have turned out to be an important host to a varied range of taxonomically diverse parasites, which exhibit a wide variety of life cycles. Whereas many of these parasites are passed directly between ultimate hosts, others need to find the way through a series of intermediate hosts before reaching a target host in which they can attain sexual maturity. The life cycles, distributions, epidemiology, clinical aspects, and, importantly, the research needed for improved risk assessments, clinical management, and prevention and control of these important parasitic diseases are discussed. Biological interactions and the ecology of fish, as well as parasites in the polluted environment, are largely indicative of toxicant accumulation, which can open up several doors to understanding the effects of parasites on the various biological or physiological parameters of host fish and setting up remedial measures to prevent economic loss. The chapter is an overview of the significance of parasitic diversity as a bioindicator of environmental pollution, taking into consideration the fish-host specificity of parasitism. The present chapter throws some light on the understanding of diverse forms of parasites that are key players in environmental sustainability and bridge the gap of parasitism, host specificity, and their ecological niche in the context of environmental pollution. The information obtained from this study will be useful in understanding the prevalence of different types of parasites in fish and will help to educate people about parasite transmission risks associated with eating raw and uncooked fish. Finally, it can be summed up that according to the parasitic prevalence, remediation or eradication strategies should be set up to avoid the loss of economically important fish due to the double-edged setback of parasitic infestations and pollution.
