CHAPTER ONE
Fishing is an important component of aquaculture in Nigeria. Fish is important as a source of protein with low cholesterol level in the diets of the populace and economically as a source of subsistence income (Aken’ova, 2000). In line with the increasing aquaculture activities, substantial information has been generated on aquaculture-related subjects in the country. An exception is fish diseases. Outbreaks of disease, however, constrain sustainable aquaculture production unless comprehensive management strategies are in place (Subasinghe et al, 2001; Bondad-Reantaso et al. 2005). Preliminary investigations into disease outbreaks in fish farming systems have reported a number of conditions resulting in mortality (Akoll 2005; Florio et al. 2009). Scarcity of information on aetiological agents hampers the development of cost-effective and ecologically sustainable strategies for disease control (Subasinghe et al. 2001; Bondad- Reantaso et al. 2005). With high fish stocking densities under commercial fish production, parasite outbreaks will undoubtedly increase (Michel 1989; Meyer 1991; Bondad- Reantaso et al. 2005).
All fishes are potential host to many different species of parasites that cause significant mortalities among captive and wild fish stocks. The crowding effects and frequent water deterioration provide ideal conditions for the transmission and proliferation of parasites, particularly for species with direct life cycles. Moreover, it is a common practice to polyculture Oreochromis niloticus with Clarias gariepinus in an attempt to control the proliferative reproduction of tilapia in Uganda. However, variation in host specificity between and within parasite groups, especially monogeneans, polyculture pose a threat of parasite cross-transmission (Sasal et al. 1999; Bakke et al. 2002; Cribb et al. 2002). Due to differences in host immunity, infection with parasites from different hosts may inflict strong pathologies and possibilities of mortalities. Accurate identification of parasites is therefore important so that a build-up of parasite numbers can be prevented.
Fish health and fish diseases are becoming more important as certain fish species are becoming more important as a ready food source for growing populations of not only the United States, but other countries as well. Parasites are found in both captive and wild fish populations, but in wild populations they maintain a kind of equilibrium until something happens to upset that balance. Wild fish are also reported to have larger parasite species diversity than fish that are raised in hatcheries (Hoffman 1998).
Information about the mode of transmission and potential intermediate hosts is often crucial to select the most appropriate management action to reduce or eliminate the problem. Present approach to treatment of parasitic diseases is largely limited to those on external surfaces and the intestinal lumen. So blood parasites and encysted worms cannot be treated effectively and economically. The Internal or endoparasitesof fish inhabits the digestive tract or other organs in the body while external or ectoparasites attach themselves to the gills, skin and fins of fish (Saurabh, 2007).
As the world population grows, fish resources are being depleted at an alarming rate as a result of over harvesting, and pollution, thus fish production is struggling to meet the increasing demand of the growing population. Poor environmental conditions and pollution often result in reduced immunity of fish and increased susceptibility to parasitic infestation and disease (Murray,2005). There is appreciable documentation of parasites of Tilapia in Nigeria. One of the earliest reports in Nigerian inland waters concerning fish parasites was that of Awachie (1965) who documented preliminary information on the parasites of fish in the Kainji reservoir. He observed that not many fishes were infected. However, in a similar study, Ukoli (1969) observed heavy parasitic infection of fish species from the same reservoir. Similarly, the reports of Oniye et al. (2004) in Zaria and Yakubu et al. (2002) in Plateau State are of great value. Various parasites are associated with Tilapia species in the wild and cultured environment where they cause morbidity, mortality, and economic losses to aquaculture in various parts of the world (Subashinghe, 1995). Awharitowa and Ehigiator (2012) isolated Dichelyne species, Echinocephalus species, Procamallanus laeviconchus and Oxyuris species of nematodes; Clinostomum tilapiae , Nemagasolena chaetodipteri and Metacercariae of trematodes; Wenyonia virilis , a Cestode and Acanthogyrus tilapiae , an acanthocephalan, all from rivers in southern Nigeria.
Parasitic diseases of fish are of particular importance in the tropics. Parasites usually exist in equilibrium with their host as a survival strategy. However, in instances where hosts are overcrowded such as in aquaria or in fish farms, parasitic diseases can spread very rapidly causing high mortality. Although, this is usually not the case in the wild natural aquatic environments, it occurs when the environment is disturbed by human activity and interference especially with populations which alter the natural distribution of their parasite communities (Imam and Dewu, 2010).
Ayanda (2009) reported Amonotaenia and Polyonchobothrium species of Cestodes; Procamallanus and Paracamallanus species of nematodes and Neoechinorhynchus species of acanthocephalans in wild and cultured Clarias gariepinus in Ilorin, North central Nigeria; while Hussein et al. (2012) reported Capillaria, Contracaecum and Cestodes in Clarias gariepinus caught from Lake Hawassa, Ethiopia.
As yet no epidemics of endoparasites have been reported in Nigeria, is likely that as fish culture becomes more intensive and widespread, fish parasites are likely to become a serious economic and health issues (Imam and Dewu, 2010). As a result of this, there is need for the study of fish parasites with the aim of controlling them.
AIMS AND OBJECTIVES
AIMS: the aim of this study is to determine the prevalence of endoparasites in the gastro-intestinal tracts of nile tilapia (Oreochromis niloticus) in Giri river, Gwagwalada area council, Fct-Abuja
OBJECTIVES
- 1. To identify the endo-parasites of the gastro intestinal tracts of nile tilapia (Oreochromis niloticus) in Giri river,
- 2. To determine prevalence of endo-parasites in the gastro intestinal tract of nile tilapia (Oreochromis niloticus) in relation to its total length, sex and weight in Giri river.
