ABSTRACT
Biochemical, haematological and biometric studies of the African lungfish, Protopterus annectens were carried out in order to establish their mean and reference values which would serve as baseline data for assessment of the health status of the fish as well as reference point for future comparative surveys. The study was carried out between March and August, 2015. In the present study, blood was analyzed using standard techniques, and differences in haematological parameters including haemoglobin concentration, red blood cell count (RBC), white blood cell count (WBC), packed cell volume (PCV), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) were determined. Biochemical parameters such as alkaline phosphate (ALP), aspartate transaminase (AST), alanine transaminase (ALT), total protein, albumin, globuline, glucose, cholesterol level, and urea were determined. Biometric parameters such as condition factor (K), hepatosomatic index, and gonadosomatic index were also determined. These haematological, biochemical and biometric parameters of fish were compared according to sex and seasons. Analysis of variance showed that there were significant differences (P < 0.05) in ALP, AST, ALT, Protein, PCV, RBC, WBC, Hb and MCV, between sex and season. The results indicated that blood parameter level such as PCV, RBC, WBC, Hb, MCV, and MCHC between sexes in dry season were significantly different from those measured in wet seasons. The result also indicated that there were significant (P < 0.05) differences in condition factor (K), hepatosomatic index (HSI) and gonadosomatic index (GSI) between the seasons. There were no significant differences in MCH and MCHC values between the sexes. The values of WBC and PCV were found to be higher in female fish especially in dry season, while the level of haemoglobin and MCV values were higher in male Protopterus annectens. This may be related to the aggressiveness of the male fish. All the biochemistry parameters were higher in dry season except cholesterol and urea, but no significant differences were found among the sexes. The length of the fish varied significantly with season. The highest length was recorded in the March and June, while the highest mean weight frequency was obtained in the month of August. The length-weight relationship showed a negative allometric growth and the condition factor indicated that the fish were in a good condition in the months of April and July. There was increase in Hepatosomatic index (HSI), as the fish length increased. The results of the present study provide useful information for monitoring changes in the health status of fish.
CHAPTER ONE
INTRODUCTION AND LITERATURE REVIEW
1.1 Introduction
It is recognized that the blood component value exhibit genetic and physiological variations. The genetic variation may be due to site-specific factors within species. Blood comprises 1.3-7% of the total body weight of fish and it represent one of the most active components that contribute to metabolic processes by ensuring gas exchange between the organism and the environment. For this reason, blood parameters are increasingly used as indicators of the physiological condition of sub-lethal stress response in fish to endogenous or exogenous change (Belanger et al., 2001; Mohammadizadeh et al., 2012). In live fish, heamatology and plasma biochemistry provide a minimally invasive tool that can support health of fish, especially in relation to determining potential effects associated with such factors as pollution, disease, age, sex, seasonality and reproduction (Pradhan et al., 2012). Changes in hematological parameters depend upon the aquatic biotope, fish species, age, sexual maturity and health status. The evaluation of physiological condition of fish depends on the availability of reference values. These should be as close as possible to normal values of various blood components considered as reliable descriptors of healthy fish under natural conditions (Pradhan et al., 2012). It is clear that the environment in which fish live influences the metabolic content in blood. Thus, haematological, biochemical and biometric parameters are closely related to the response of the animal to the environment, an indication that the environment where fishes live could exert some influence on the heamatological characteristics (Gabriel et al., 2012). Taking into account the long evolutionary history of fishes and the adaptation to different environment, it is obvious that no species can be used as a representative model for all fishes. One of the difficulties in assessing the state of propagation of natural fish population has been the paucity of reliable reference values in healthy animals under natural habitat (Pradhan et al., 2012).
The African lungfish, Protopterus annectens is a highly prized food fish in Nigeria (Otuogbai, 2001; Otuogbai and Ikhenoba, 2012). It is distributed in shallow parts of rivers and lakes of some West African countries ranging from Senegal to Cameroon where it contributes to a relatively high percentage of artisanal fisheries (Otuogbai, 2001; Otuogbai and Ikhenoba, 2001; Okafor, 2004). Protopterus are omnivores in nature, feeding on fish, shellfish, amphibians and plant matter (Otuogbai, 2001).
