CHAPTER ONE
1.0 INTRODUCTION
Fish has been one of the main foods for humans for many centuries and still constitute an important part of the diet in many countries (Leisneret al., 1995). In Nigeria, the short supplies of animal protein together with the increasing human population have raised the cost of animal protein to a level almost beyond the reach of the low income group (Ezeriet al.,2001). As a result, there is a considerable increase in the demand for fish being thecheapest source of animal protein. (Ladipoetal., 1981). The advantages of fish as a food are its easy digestibility and high nutritional value (Leisneret al., 1995). These important attributes make the commodity readily susceptible to microbial attack particularly bacteria (Adams et al., 1999). Fish flesh naturally contains very low levels of carbohydrates and these are further depleted during the death struggle of the fish (Adams et al., 1999). This has two important consequences for spoilage. Firstly, it limits degree of post mortem acidification of the tissue so that the ultimate pH of the muscles is 6.2-6.5 (Adamsetal., 1999).Disease breaks out in fish tank very quickly and you have to first identity the type of disease before you can take action.
The bacteria are transmitted by fish that have made contact with other diseased fish. Bacterialfish disease and infections are very common and are one of mostdifficult health problems toDeal with (Douglas et al., 2007). Bacteria can enter the fish body through the gills or skin or it can stay on the body surface of the fish (Douglas et al, 2007). There are four types of bacterial infections. Bacterial gill disease: The gills are the primary target Systemic bacterial disease: bacteria invades the fish’s body and damages internal organs, bacterial body ulcers: Lesions on the fish body that can be shallow or deep and fin rot: Most likely resulting from environmental stress. (Douglass et al., 2007). Secondly, the absence of carbohydrate means that bacteria present on the fish will immediately resort to using the soluble pool of readily assimilated nitrogenous material, producing off-odor. (Adams et al., 1999) Shell fish such as Tilapia have a particular large pool of nitrogenous extractives and are even more prone to raid spoilage, a factor which accounts for the common practice of keeping them alive until immediately prior to consumption (Adams et al., 1999). The speed with which a product spoils is also related to the initial microbial load on the product: the higher the count, the sooner spoilage occurs (Adams etal., 1999). The fresh water or rivers and lakes have a complex flora of microorganisms which include genuinely aquatic species as well as component introduced from terrestrial, animal and plant sources. (Adams et al., 1999). The scale of human activities has had a detrimental effect on coastal waters. Many shell fishes used for food out particles from large volume of waters. If these waters have been contaminated with sewage, there is always the risk that enteroorganisms from infected individuals may be present and will be concentrated by the filterfeeding activities of shell fish (Adams et al.,1999). Also during handling of the commodity,the natural flora of the environment may becontaminated with organisms associated withman such as members of the enterobacteriaceaeand Staphylococcus aureuswhich can grow wellat 30-37oc (Micealet al., 2007). By monitoring the bacteria contents of fish organs, the quality of fish can be measured since these will affect the storage life and quality of the fishery products (Kaneko et al., 1971). In order to provide a predictive capability for possible disease outbreaks and provide an opportunity to design preventive management actions, detailed information of the bacterial load and types of bacteria associated with the organs of apparently healthy Tilapia fish is needed.
AIM
To determine the bacterial microflora of fresh water fish (Tilapia).
OBJECTIVES
- To determine the type of microorganism in the gill, skin and intestine.
- To determine the type of micro algae found in the pond.
