A comparative study of helminth parasites from the fish Tilapia zillii and Oreochromis leucostictus in Lake Naivasha and Oloidien Bay, Kenya

Abstract

The parasitic fauna of two fish species, namely gill-netted samples of 652 Oreochromis leucostictus and 448 Tilapia zillii from Lake Naivasha and Oloidien Bay was investigated during the period from the end of October 1995 to September 1996. Five larval helminth parasites were recovered including the nematode, Contracaecum sp., the acanthocephalan Polyacanthorhynchus kenyensis, the digenetic trematode, Clinostomum sp. and two cestodes, Amirthalingamia sp. and Cyclustera sp. Both prevalence and intensity of the infection of these helminths increased in larger sized fish, whereas male fish were more heavily infected than females. No seasonality in infection level were observed. The health status of both fish species remained unaffected, although O. leucostictus from Oloidien Bay which harboured heavy infections of Contracaecum exhibited stuntedness and the lack of fatty deposits around the digestive caecum.

Parasite communities of the elongate tigerfish Hydrocynus forskahlii (Cuvier 1819) and redbelly tilapia Tilapia zillii (Gervais 1848) from Lake Turkana, Kenya: influence of host sex and size

“…In contrast, several surveys have shown a less diverse parasite fauna in T. zillii elsewhere in Africa (Ramadan 1991;Olofintoye 2006;Abdel-Hady et al 2008;Goselle et al 2008;Bichi and Ibrahim 2009;Morenikeji and Adepeju 2009;Hassan et al 2012;Olurin et al 2012). The low infection intensity of most of the parasites that we found in T. zillii is similar to that reported by Aloo (2002), who concluded that among the tilapiine species, T. zillii is probably more resistant to parasitic infections than the other species.…”

Infection patterns of Nile tilapia (Oreochromis niloticus L.) by two helminth species with contrasting life styles

“…Overall, the lack of significant differences in infection level between fish sexes is similar to previous studies with other fish species (Pennycuick 1971;González and Acuña 2000). Our findings contrast to those studies of Zuk and McKean (1996), Poulin (1996), Reimchen and Nosil (2001) and Aloo (2002), who reported that male individuals are highly susceptible to parasites because of differential exposure to parasites related to sexspecific feeding and habitat use strategies (Zuk andMcKean 1996, Poulin 1996;Reimchen and Nosil 2001). In the present waters, the sex-related behaviour change in O. niloticus appears to be too short-lived to significantly alter exposure to heteroxenous helminths.…”

“…The plerocercoids of A. macracantha (order: Cyclophyillidea, family: Gryporhynchidea) have been reported, so far, in two cichlids: Tilapia zillii and O. niloticus (Aloo 2002;Scholz et al 2004). The parasite is transmitted to fish through zooplankton, presumably crustaceans of the genus Cyclops (Scholz et al 2004).…”

“…No information is available regarding the transmission requirements (Scholz et al 2004). Infection dynamics study by Aloo (2002) in Lake Naivasha reported an increase in the prevalence and intensity of A. macracantha in T. zillii with fish size. Male fish were more heavily infected than females.…”

“…The existing information is inconsistent. Some studies found no seasonality in parasite populations (Aloo 2002;Vincent and Font 2003). Other studies reported apparent seasonal variations in parasite abundance associated with rainfall (Steinauer and Font 2003;Jiménez-García and VidalMartínez 2005;Dejen et al 2006).…”