Diversity of parasites in wild Astronotus ocellatus (Perciformes, Cichlidae), an ornamental and food fish in Brazil

Abstract

The community composition of parasites was characterized in Astronotus ocellatus from a tributary of the Amazon River, northern Brazil. The prevalence was 87.9%, and a total of 526,052 parasites were collected, with a mean of 15,941 parasites per host. Nine taxa of ecto-and endo-parasites were identified, but Ichthyophthirius multifiliis was the dominant species, while Piscinoodinium pillulare, Clinostomum marginatum and Argulus multicolor were the least prevalent parasites. The parasite community was characterized by a low species richness, low diversity and low evenness. Host body size was not found to influence the composition of the parasite community, and there was no significant correlation between abundance of any parasite species and host body size. Papers published concerning the presence of parasites in this host in different hydrographic basins within Brazil indicate that 22 species of parasites are known to infect A. ocellatus, including species of ectoparasites and endoparasites. In Brazil, ectoparasites species, particularly crustaceans, have been found to parasitize A. ocellatus in relatively high numbers. This predominance of ectoparasites is typical of fish of lentic ecosystems. Finally, the presence of different endoparasites taxa suggest that A. ocellatus acts as an intermediate or definitive host.

Helminth parasites in two populations of Astronotus ocellatus (Cichliformes: Cichlidae) from the eastern Amazon, Northern Brazil

“…In addition, hosts from the Tapajós River had only species of generalist parasites, i.e. they infect many fish species in eastern Amazon (BITTENCOURT et al, 2014;OLIVEIRA et al, 2017;TAVARES-DIAS & NEVES, 2017). In addition, the absence or presence of these endoparasite species in hosts of both localities may be mainly related to differences in host diet, absence or unviability of infective stages and viability of adequate intermediate hosts between both environments (MARCOGLIESE et al, 2016;TAVARES-DIAS & NEVES, 2017;OLIVEIRA et al, 2017).…”

“…sp., with dominance of P. spiculastriatus. Parasites had an overdispersion, a common distribution pattern in A. ocellatus (TAVARES-DIAS & NEVES, 2017). Furthermore, as the population of A. ocellatus from the Iara Lake consisted of larger (older) individuals than the population of hosts from the Tapajós River, it usually could ingest more infective larvae, either directly from the intermediate host or from paratenic hosts, with the increased volume of food consumed by larger fish.…”

“…Astronotus ocellatus Agassiz, 1831 is a benthopelagic Amazonian cichlid that prefers lentic environments, finding protection under submerged branches and trunks. It is an omnivorous species, although its diet is heavily composed of fish, crustaceans, gastropods and larvae of aquatic insects, and its behavior includes ambushing and capturing prey and avoiding predators by escaping over short distances (SOARES et al, 2011;TAVARES-DIAS & NEVES, 2017;FROESE & PAULY, 2019). This fish is very important as food for Amazonian riverine populations and as an ornamental fish in aquaria (SOARES et al, 2011).…”

“…Parasites provide an interesting model for studying organization and structure of parasite communities in wild fish populations (FRANCOVÁ & ONDRAČKOVÁ, 2011;MARCOGLIESE et al, 2016;TAVARES-DIAS & NEVES, 2017;OLIVEIRA et al, 2017). For A. ocellatus from the Brazil, a total of 22 parasite species has been estimated; in addition some composition and structural patterns were detected in the parasite community, such as dominance of monogenean species, dominance of ectoparasite species with crustacean infracommunities more diverse than other ectoparasites, overdispersion of ectoparasites and endoparasites, interspecific associations in the ectoparasite infracommunities, specifically a combination of generalist and specialist parasites that may contribute to host population control and correlation between parasite abundance and host total body size at the infracommunity level (TAVARES-DIAS & NEVES, 2017). However, this is probably an underestimation of the actual diversity, due to differences in species richness of parasites for different environments, since Pinheiro et al (2018) has recently described a new species of nematode for A. ocellatus from the eastern Amazon, Procamallanus spiculastriatus.…”

“…In each wild host population, the structure and composition of the parasite communities are constituted from a set of parasite species available in the environment (FRANCOVÁ & ONDRAČKOVÁ, 2011;BITTENCOURT et al, 2014;MARCOGLIESE et al, 2016;OLIVEIRA et al, 2017;TAVARES-DIAS & NEVES, 2017), influenced by many local factors. As a result, for the same fish species living in different environments, the component community and richness of parasites may or may not be mainly linked to environmental and climate conditions, host size, intensity of food capture by host, structure of the local food web, distance from geographic localities and availability of intermediate hosts infecting the fish populations (FRANCOVÁ & ONDRAČKOVÁ, 2011;MARCOGLIESE et al, 2016;OLIVEIRA et al, 2017;TAVARES-DIAS & NEVES, 2017). In addition, the type of parasite life cycle also plays an important role in environment-host-parasite interactions.…”