Haematological and Biochemical Indices of Cultured African Catfish (Clarias gariepinus) and Tilapia (Oreochromis niloticus) in the Savannah Guinean Highland Zone in Cameroon

Received 27 Feb, 2021

Accepted 05 Apr, 2021

Published 10 Jun, 2021

ABSTRACT Background and Objectives: Hematological indices are important tools for characterizing physiological status and changes due to pathological processes or environmental hazards. Therefore the present study aimed at contributing to the determination of baseline values of hematological and biochemical parameters of culture indigenous fish in Cameroon. Materials and Methods: Blood samples were collected from 40 clinically healthy fish including 20 African catfish (Clarias gariepinus) and 20 tilapia Nile (Oreochromis niloticus)from June to August 2019 in the Adamawa region of Cameroon. Results: It appears that white blood cells, monocytes, red blood cells, hemoglobin, hematocrit, mean corpuscular hemoglobin, platelets count, thrombocyte count, mean platelet volume, platelets distribution, macroplatelet count, macroplatelet percentage and glucose concentrations were significantly (p<0.05) higher in C. gariepinus compared to the values obtained in O. niloticus. In contrast, blood creatinine was higher (p<0.05) in O. niloticus than in C. gariepinus. In African catfish, white blood cell and haemoglobin levels were significantly (p<0.05) higher in fish with sizes less than or equal to 20 cm. In Nile tilapia, fish with sizes varying between 21 and 30 cm had significantly (p<0.05) higher levels of white blood cells, lymphocytes, red blood cells, hemoglobin and hematocrit compared to those less than 21 cm. Conclusion: This study provides the physiological values of some haematological and biochemical parameters in C. gariepinus and O. niloticus in Ngaoundere in Cameroon.

INTRODUCTION

Aquaculture continues to be the fastest growing animal food-producing sector, accounting for about 46% of total food fish supply and 52% of fish for human consumption¹. A significant percentage of production in 2018 came from Asia (34%), followed by America(14%), Europe (10%) and Africa (7%). The total fish production had almost doubled during the last 20 years in Africa¹. Aquaculture sector contributes significantly to the livelihood of many households of rural population in low and middle incomes countries (LMICs) like Cameroon². As such, aquaculture plays a significant role in food security and poverty alleviation³. The contribution of fisheries and aquaculture is less than 1% of GDP in Cameroonand population's demand is estimated at more than 400,000 tons per year⁴. As a result of the increase in productivity, farmers constantly used veterinary drugs for diseases prevention, control or for growth promotion⁵. However, abusive use of these substances may hamper fish health status. Also, environmental pollution is another crude menace for aquatic ecosystems⁶. Inappropriate disposal of wastes from farms, domestic and industries finally find their way into the aquatic environment. The agricultural drainage water containing pesticides and fertilizers, effluents from industrial activities and runoffs in addition to sewage effluents supply the water bodies used in fish pond. Therefore, these potential hazards may influence the haematological and biochemical parameters of indigenous or culture species in the local climate conditions⁴.

Haematologicaland biochemicalanalysis are generally carried out for diagnostic or prophylactic purposes such as health check-ups⁷. Hematological indices are important tools for characterizing physiological status and changes due to pathological processes or environmental hazards. The determination of haematological and biochemical reference values in fish is more difficult than in higher vertebrates due to their poikilothermism and high spatial, temporal and individual variability⁸. In order to reach a conclusion about the healthy or pathological status of an individual, it is recommended to compare the values of the biochemical parameters of the examined individual with the pre-set usual or reference values. The International Federation of Clinical Chemistry (IFCCC), International Council for Standardization in (ICSH) and Clinical Laboratory Standard Institute (CLSI) are among the units of the National Committee for Clinical Laboratory Standards (NCCLS) recommends that each country should establish reference intervals for healthy individuals from a homogeneous population group to permit rational interpretation of the analysis⁹. Therefore, the present study is aimed at contributing to the determination of baseline values of hematological and biochemical parameters of cultured indigenous fish in Cameroon.

MATERIALS AND METHODS

Study area: This study was carried out from June to August 2019 in Ngaoundere (7°09'-7°70'N and 13°52'-13°70'E) in the Vina Division of the Adamawa Region of Cameroon. The Adamawa region is located in the Savannah Guinean highland, in the mid to high altitude zones of Cameroon with average annual precipitations of 1200-1600 mm in the rainy season which runs from around mid-March to October. Mean temperature ranges from 23-26°C with a maximumof up to 32°C¹⁰.

Fish sample collection: A sample of 40 apparently healthy individuals, consisting of 20 African catfish (Clariasgariepinus with variable sizes between 17.5 to 29.3 cm, weight between 70 to 400 g and 20 Nile tilapia (Oreochromis niloticus) with variable sizes (18 to 25 cm) and weight (200 to 700 g)⁹ was collected. The criteria of good health were defined as follows: no declared pathology, normal clinical examination (no signs of pathology) on the day of collection, and no ongoing treatment. Water temperature and pH were measured on site using a portable HANNA Instrument HI 8424. A millimeter ruler was used to measure the total length, standard length, head width, body width, bodyheight and head length for all individuals. The weight was determined using an Electronic Scale.

Blood Collection, Haematological and biochemical Examination: Blood samples were collected from the caudal peduncle using a 5ml syringe and needle that has been treated with anti-coagulant such as heparin to prevent clotting, and poured into small sampling bottles containing Ethylene diamine tetra-acetic acid (EDTA). After the collection, the blood samples were taken to the Veterinary Research Laboratory of the Institute of Agricultural Research for Development (IRAD), Wakwa Regional Center, Ngaoundere, Cameroon where the haematological and biochemical analysis were carried out. Part of the whole blood sample was used to estimate parameters such as red blood cells (RBC), white blood cells (WBC) count and packed cell volume (PCV) and this was performed using a DIATRON blood cell counting machine (ABACUS JUNIOR-30, Analyzer with 3 parts differentiation, HUNGARY). The remains of the blood collected in the EDTA tube was centrifuged and the serum obtained was used for biochemical analysis. Total protein and glucose were determined using an automated SECOMAM instrument following the linear colorimetric method. Creatinine was determined using a MIDRAY 8A-88A Automated device following standard procedures.

Data analysis: The data was registered in Microsoft excel 2016 (Microsoft Corporation, Redmond, WA, USA) and analyzed using IBM SPSS Statistics version 25. Student test and one-way ANOVA were used to compare the means. For non-parametric data, the MANN-WHITNEY test was used for comparisons. Data were presented as means ± standard deviation. Differences were considered statistically significant based on p<0.05.

RESULTS

Haematological and biochemical parameters of Clarias gariepinus and Oreochromis niloticus: White blood cells (108.09±11.97), monocytes (19.24±9.15), red blood cells (2.08±0.35), hemoglobin (11.87±2.11), mean corpuscular hemoglobin (56.26±2.85), platelets count (42.12±1.28) and glucose concentration (137.69±96.9) were significantly (p<0.05) higher in C. gariepinus compared to the values determined in O. niloticus. In contrast, blood creatinine (0.49±0.12) was higher (p<0.05) in O. niloticusthan in C. gariepinus (Table 1). In African catfish, white blood cell (114.22±4.91) and haemoglobin levels (12.73±1.60) were significantly (p<0.05) higher in fish with size less than or equal to 20 cm, while no significant difference (p>0.05) was noted between the biochemical parameters evaluated (Table 2). In Nile tilapia, fish with size varying between 21 and 30 cm had significantly (p<0.05) higher levels of white blood cells (75.97±9.09), lymphocytes (60.63±7.81), hemoglobin (10.20±1.19) and hematocrit (23.12±2.85) compared to those less than 21 cm (Table 3). In C. gariepinus, white blood cell (113.39±8.95), red blood cell (2.42±0.41), hemoglobin (12.97±2.37) and hematocrit(32.63±5.86) varied significantly (p<0.05) with body weight ranged between 200 and 300 g (Table 4). The concentration of white blood cells (80.09±1.73), Mean Corpuscular Hemoglobin Concentration (44.07±2.80), hemoglobin (11.03±0.11) and hematocrit (25.33±1.50) significantly (p<0.05) increased in fish with body weight of more than 300 g in O. niloticus (Table 5).

Table 1: Mean ± SD of the hematological and biochemical parameters in clinically healthy Oreochromis niloticus and Clarias gariepinus in the Savannah Guinean highland zone in Cameroon
	C. gariepinus (n = 20)	O. niloticus (n = 20)	p-value
Haematological parametres
White Blood Cells (103/μl)	108.09±11.97a	68.39±12.70b	0.00
Lymphocytes (103/μl)	548.24±21.46a	54.54±12.36a	0.31
Monocytes (103/μl)	19.24±9.15a	9.12±5.16b	0.00
Granulocytes (103/μl)	10.75±10.52a	4.76±3.05a	0.23
Lymphocytes (%)	71.69±15.61a	79.73±12.09a	0.76
Monocytes (%)	17.45±7.76a	13.24±7.83a	0.96
Granulocytes (%)	9.92±9.41a	7.03±4.68a	0.23
Red Blood Cells (106/μl)	2.08±0.35a	1.50±0.30b	0.00
Hemoglobine (g/dl)	11.87±2.11a	8.84±1.86b	0.00
Hematocrite (%)	27.49±5.11a	19.82±4.56b	0.00
Mean Cell Volume (fl)	130.85±5.11a	131.65±8.29a	0.72
Mean Corpuscular Hemoglobin Level (pg)	56.26±2.85a	58.98±2.59b	0.03
Mean Corpuscular Hemoglobin Level (g/dl)	43.25±2.56a	44.97±3.33a	0.07
DRBC (%)	11.43±1.35a	11.30±5.17a	0.92
Blood platelets (103/μl)	101.20±25.23a	81.70±16.76b	0.007
Thrombocyte Count (%)	0.10±0.03a	0.08±0.02b	0.008
Mean Platelet Volume (fl)	9.90±0.63a	9.54±0.53a	0.05
Platelet Distribution (%)	42.12±1.28a	40.35±1.99b	0.002
Number of Macro Platelets (103/μl)	40.25±11.38a	28.20±8.65b	0.001
Percentage of Macro Platelets (%)	39.72±3.72a	36.29±4.48b	0.01
Biochemical parameters
Creatinine (mg/dl)	0.42±0.09a	0.49±0.12b	0.04
Total Protein (mg/dl)	4.22±1.06a	4.20±1.31a	0.98
Glucose (mg/dl)	137.69±96.9a	81.04±37.23b	0.02
SD: standard deviation; n: sample size; (a, b): Same superscript alphabets in the same row are not significantly different (P>0.05).

Table 2: Variations in haematological and biochemical parameter values with size in clinically healthy Clarias gariepinus in the Savannah Guinean highland zone in Cameroon
	Fish size		p-value
	≤ 20 cm (n = 11)	[21 - 30] cm (n = 9)
Haematyological parameters
White Blood Cells (103/µl)	114.22±4.91a	100.60±13.97b	0.007
>Lymphocyte (103/µl)	79.84±20.83a	1120.73±3133.27a	0.28
Monocytes (103/µl)	22.11±10.62a	15.72±5.69a	0.12
Granulocytes (103/µl)	13.06±12.28a	7.93±7.62a	0.29
Lymphocyte (%)	68.43±17.82a	75.67±12.22a	0.32
Monocytes (%)	19.16±8.93a	15.34±5.84a	0.29
Granulocytes (%)	11.43±10.51a	8.08±8.06a	0.44
Red Blood Cells (106/µl)	2.21±0.29a	1.93±0.37a	0.07
Hemoglobin (g/dl)	12.73±1.60a	10.82±2.25b	0.04
Hematocrit (%)	29.37±4.49a	25.20±5.09a	0.07
Mean Cell Volume (fl)	131.27±4.92a	130.33±5.59a	0.69
Mean Corpuscular Hemoglobin Level (pg)	56.28±3.33a	56.22±2.32a	0.96
Corpuscular Hemoglobin Concentration (g/dl)	43.34±2.73a	43.13±2.48a	0.86
DRBC (%)	11.73±1.57a	11.06±0.98a	0.28
Blood platelets(103/µl)	99.36±22.08a	103.44±29.87a	0.73
Thrombocyte Count (%)	0.10±0.03a	0.10±0.03a	1.00
Mean Platelet Volume (fl)	10.01±0.56a	9.77±0.75a	0.40
Platelet Distribution (%)	41.93±0.85a	42.36±1.70a	0.47
Number of Macro Platelets (103/µl)	40.27±9.74a	40.22±13.75a	0.99
Percentage of Macro Platelets (%)	40.48±2.82a	38.79±4.60a	0.33
Biochemical parameters
Creatinine (mg/dl)	0.43±0.08a	0.41±0.12a	0.72
Total Protein (mg/dl)	4.0418±1.12a	4.43±1.01a	0.43
Glucose (mg/dl)	126.62±98.48a	151.22±99.11a	0.59
n: sample size; (a, b): Same superscript alphabets in the same row are not significantly different (P>0.05).

Table 3: Variations in haematological and Biochemical Parameter Values with size in clinically healthy Oreochromis niloticus in the Savannah Guinean highland zone in Cameroon
	Lengh of fish		p-value
	< 20 cm (n=9)	[21 - 30] cm (n=11)
Haematological parameters
White Blood Cells (103/μl)	59.12±10.21a	75.97±9.09b	0.001
Lymphocytes (103/μl)	47.09±13.16a	60.63±7.81b	0.01
Monocytes (103/μl)	7.47±5.24a	10.46±4.92a	0.21
Granulocytes (103/μl)	4.60±2.89a	4.88±3.31a	0.85
Lymphocytes (%)	79.12±15.65a	80.21±9.005a	0.85
Monocytes (%)	12.94±10.37a	13.47±5.49a	0.89
Granulocytes (%)	7.91±5.61a	6.30±3.90a	0.46
Red Blood Cells (106/μl)	1.23±0.16a	1.71±0.18b	0.00
Hemoglobine (g/dl)	7.18±0.89a	10.20±1.19b	0.00
Hematocrite (%)	15.79±2.44a	23.12±2.85b	0.00
Mean Cell Volume (fl)	127.89±9.78a	134.73±5.57a	0.07
Mean Corpuscular Hemoglobin Level(pg)	58.31±2.36a	59.53±2.75a	0.31
Mean Corpuscular Hemoglobin Concentration (g/dl)	45.85±4.27a	44.25±2.30a	0.29
DRBC (%)	8.98±5.59a	13.20±4.12a	0.07
Blood platelets (103/μl)	77.66±9.86a	85.00±20.71a	0.34
Thrombocyte Count (%)	0.07±0.01a	0.08±0.02a	0.37
Mean Platelet Volume (fl)	9.48±0.54a	9.57±0.54a	0.73
Platelet Distribution (%)	39.83±2.05a	40.77±1.93a	0.31
Number of Macro Platelets(103/μl)	24.78±10.00a	31.00±6.56a	0.11
Percentage of Macro Platelets (%)	35.81±4.91a	36.69±4.30a	0.67
Biochemical parameters
Creatinine (mg/dl)	0.47±0.13a	0.52±0.12a	0.36
Total Protein (mg/dl)	4.63±1.48a	3.85±1.10a	0.19
Glucose (mg/dl)	87.55±48.79a	75.72±25.69a	0.49
n: sample size; (a, b): Same superscript alphabets in the same row are not significantly different (P>0.05).

Table 4: Variations in haematologicaland biochemical parameter values as a function of live weight in clinically healthy Clarias gariepinus in the Savannah Guinean highland zone in Cameroon
	Weight of fish			p-value
	< 200g (n = 14)	[200g-300g] (n = 3)	> 300g (n = 3)
Haematological parameters
White Blood Cells (103/μl)	112.12±5.94a	113.39±8.95b	84.00±5.0ab	0.00
Lymphocytes (103/μl)	54.95±25.13 a	70.14±30.74a	61.68±16.0a	0.81
Monocytes (103/μl)	18.77±7.66a	27.18±12.59a	13.46±10.4a	0.18
Granulocytes (103/μl)	10.02±9.76a	16.06±17.18a	8.86±9.20a	0.65
Lymphocytes (%)	73.28±12.37a	61.83±26.20a	74.07±21.4a	0.52
Monocytes (%)	16.41±6.11a	24.03±11.08a	15.70±11.3a	0.29
Granulocytes (%)	8.94±8.55a	14.17±15.09a	10.23±10.1a	0.71
Red Blood Cells (106/μl)	2.12±0.25a	2.42±0.41b	1.56±0.06ab	0.003
Hemoglobin (g/dl)	12.31±1.68a	12.97±2.37b	8.73±0.46ab	0.009
Hematocrit (%)	28.04±3.51a	32.63±5.86b	19.81±1.70ab	0.002
MeanCell Volume (fl)	130.71±4.61a	135.00±5.29 a	127.33±6.11	0.19
Mean Corpuscular Hemoglobin level(pg)	56.89±2.73a	53.53±2.56a	56.00±2.85 a	0.18
Mean Corpuscular Hemoglobin Concentration (g/dl)	43.84±2.19a	39.63±0.38b	44.07±2.80ab	0.02
Distribution of Red Blood Cells (%)	11.36±1.35a	11.83±1.83 a	11.33±1.30 a	0.86
Blood platelets (103/μl)	98.79±26.60a	125.67±14.64a	88.00±6.00a	0.15
Thrombocyte Count (%)	0.09±0.03a	0.12±0.02	0.09±0.005 a	0.21
Mean Platelet Volume (fl)	9.88±0.45a	10.30±0.60	9.60±1.32 a	0.41
Platelet Distribution (%)	41.94±1.01a	42.37±0.94 a	42.70±2.70 a	0.63
Number of Macro Platelets (103/μl)	39.36±11.65a	51.33±7.51a	33.33±5.51a	0.13
Percentage of Macro Platelets (%)	39.81±2.87 a	40.84±3.36	38.17±7.81 a	0.69
Biochemicalparameters
Creatinine (mg/dl)	0.44±0.08a	0.37±0.15a	0.37±0.06a	0.27
Total Protein (mg/dl)	3.93±0.81a	5.15±1.65a	4.58±1.32a	0.16
Glucose(mg/dl)	155.07±88.74a	75.79±101.98a	118.46±138.87a	0.43
n: sample size; (a, b): Same superscript alphabets in the same row are not significantly different (P>0.05).

Table 5: Variations in Haematological and Biochemical Parameter Values as a function of live weight in clinically healthy Oreochromis niloticus in the Savannah Guinean highland zone in Cameroon
	Weight of fish			p-value
	< 200g (n = 14)	[200g-300g] (n = 3)	> 300g (n = 3)
Haematologicalparameters
White Blood Cells (103/μl)	62.64±12.06a	73.07±11.84b	80.09±1.73 ab	0.05
Lymphocytes (103/μl)	50.77±14.36a	56.17±7.72a	65.09±4.44a	0.19
Monocytes (103/μl)	7.66±4.72a	10.76±6.50a	11.17±3.16a	0.39
Granulocytes (103/μl)	4.25±2.73a	6.14±4.01a	3.86±1.76a	0.43
Lymphocytes (%)	80.33±14.25a	77.83±11.30a	81.30±6.05a	0.90
Monocytes (%)	12.56±9.33a	14.13±7.11a	13.90±3.85a	0.92
Granulocytes (%)	7.09±5.35a	8.02±4.46a	4.80±2.23a	0.64
Red Blood Cells (106/μl)	1.31±0.22a	1.65±0.19b	1.88±0.14ab	0.001
Hemoglobin (g/dl)	7.72±1.45a	9.80±1.47b	11.03±0.11ab	0.002
Hematocrit (%)	17.05±3.58a	22.13±3.31b	25.33±1.50ab	0.002
Mean Cell Volume (fl)	129.72±9.75a	133.67±6.80a	134.67±4.04a	0.53
Mean Corpuscular Hemoglobin Level (pg)	58.90±2.77a	59.20±1.95a	58.83±3.95a	0.97
Mean Corpuscular Hemoglobin Concentration (g/dl)	45.64±4.07a	44.40±1.93a	43.63±2.68a	0.60
Distribution of Red Blood Cells (%)	9.39±5.12a	13.45±4.98a	14.00±3.83a	0.19
Blood platelets(103/μl)	76.90±9.93a	90.17±25.67a	82.33±13.58a	0.31
Thrombocyte Count (%)	0.07±0.01a	0.08±0.02 a	0.08±0.01a	0.48
Mean Platelet Volume (fl)	9.59±0.54a	9.35±0.58 a	9.70±0.40a	0.59
Platelet Distribution (%)	40.10±1.94a	40.67±1.99a	40.63±2.84a	0.84
Number of Macro Platelets (103/μl)	25.64±9.22a	31.67±8.82a	30.67±3.21a	0.37
Percentage of Macro Platelets (%)	36.71±4.94a	34.94±4.07a	37.48±4.37a	0.68
Biochemical parameters
Creatinine (mg/dl)	0.47±0.13a	0.52±0.12a		0.39
Total Protein (mg/dl)	4.66±1.37a	3.65±1.05a		0.09
Glucose (mg/dl)	82.86±44.87a	78.82±27.67a		0.82
n: sample size; (a, b): ): Same superscript alphabets in the same row are not significantly different (P>0.05).

Interactions between blood and biometric parameters: Table 6 shows the correlations between blood and biometric parameters, including body height and weight in C. gariepinus and O. niloticus. White blood cells (r = -0.879), red blood cells (r = -0.670), hemoglobin (r = -0.691), hematocrit (r = -0.642) were negatively correlated with strongest correlation with fish size in C. gariepinus. White blood cells (r = -0.809), and hemoglobin (r = -0.582) were negatively correlated with strongest correlation with body weight. With O. niloticus, while white blood cells (r = 0.791), lymphocytes (r = -0.654), red blood cells, hemoglobin and hematocrit (r = 0.923) were negatively correlated with strongest correlation with body weight.

Table 6: Correlations between blood parameters and biometric parameters in clinically healthy Clarias gariepinus and Oreochromis niloticus in the Savannah Guinean highland zone in Cameroon
	Clarias gariepinus		Oreochromis niloticus
	Lengh	Weight	Lengh	weight
Haematologicalparameters
White Blood Cells (103/µl)	-0.879**	-0.809**	0.791**	0.649**
Lymphocytes (103/µl)	-0.038	0.123	0.654**	0.469
Monocytes (103/µl)	-0.297	-0.153	0.331	0.349
Granulocytes (103/µl)	-0.145	-0.022	0.077	0.206
Lymphocytes (%)	0.095	-0.016	0.050	-0.061
Monocytes (%)	-0.113	0.022	0.029	0.099
Granulocytes (%)	-0.044	0.064	-0.175	-0.007
Red Blood Cells (106/µl)	-0.670**	0.505	0.923**	0.796**
Hemoglobin (g/dl)	-0.691**	-0.582*	0.923*	0.805**
Hematocrit (%)	-0.642**	-0.498	0.923*	0.805*
Mean Cell Volume (fl)	-0.156	-0.137	0.479*	0.435
Mean Corpuscular Hemoglobin Level (pg)	-0.111	-0.207	0.250	0.006
Distribution of Red Blood Cells (%)	-0.159	-0.009	0.439	0.415
Blood platelets(103/µl)	-0.093	-0.038	0.097	0.104
Thrombocyte Count (%)	-0.148	-0.038	0.061	0.008
Mean Platelet Volume (fl)	-0.318	-0.123	0.066	-0.142
Platelet Distribution (%)	0.141	0.216	0.127	-0.039
Number of Macro Platelets (103/µl)	-0.208	-0.090	0.264	0.154
PMP(%)	-0.358	-0.167	0.092	-0.121
Mean Corpuscular Hemoglobin Concentration (g/dl)	-0.006	-0.115	-0.289	0.386
Biochemical parameters
Creatinine (mg/dl)	-0.283	-0.364	0.204	0.214
Total Protein (mg/dl)	0.124	0.284	-0.154	-0.208
Glucose (mg/dl)	-0.020	-0.182	-0.048	0.067
**highly significant correlation p<0.01; *significant correlation p<0.05

DISCUSSION

Haematological and biochemical analysis are generally carried out for diagnostic or prophylactic purposes such as health checks indices⁷ are important tools for characterizing physiological status and changes due to pathological processes or environmental pollution⁸. Based on the recommendation of the International Federation of Clinical Chemistry (IFCCC), the International Council for Standardization in Hematology (ICSH) and the Clinical Laboratory Standard Institute (CLSI) which are among the units of the National Committee for Clinical Laboratory Standards (NCCLS), each country must establish reference intervals for healthy individuals from a homogeneous population group to allow rational interpretation of the analyses⁹. The present study was carried out with the aim of contributing to the determination of baseline values of haematological and biochemical parameters of culture indigenous fish in Cameroon. It appears that mean values of major haematological and biochemical parameters such as white blood cells, monocytes, red blood cells, hemoglobin, hematocrit, mean corpuscular hemoglobin, platelets count, thrombocytes count, mean platelet volume, platelets distribution, macroplatelets count, percentage of macroplatelets, and glucose concentration were significantly higher in C. gariepinus, compared to values obtained in O. niloticus, with the exception of creatinine levels. These results would be explain not only by species-related differences, but also by the hardiness of C. gariepinus¹¹. In contrast, O. niloticuswas seen to have more lymphocytes, granulocytes, platelets, mean cell volume and MCHT compared to C. gariepinus and this difference may be related to the species. The hematocrit value obtained in C. gariepinus mirrors the findings reported by Tiamiyu et al.¹² in Ibadan, Nigeria and by Al-Otaiba et al.¹³ in Saudi Arabia while mean values for white blood cells, lymphocytes, percentage of granulocytes, hemoglobin, mean corpuscular hemoglobin concentration and blood platelets observed with O. niloticus were comparable to that obtained by Fagbuaro and Iwalaye¹⁴ in Nigeria and Kouassi et al.¹⁵ in Côte d'Ivoire.

A decrease in the number of white blood cells in O. niloticus compared to C. gariepinus may be due to the normal physiological reactions to toxic or infectious agents as part of the immune system's response. Bioconcentration of certain metals in the kidney and liver, as well as primary or secondary changes in haematopoietic organs⁴ can induce oxidative stress and relate s to the decrease in white blood cells¹⁶. High level of red blood cells and haemoglobin concentrationin C. gariepinus compared to O. niloticus may be in relation withthe high anaerobic metabolic capacity of this species to survive in extreme conditions, which is a clear advantage for its rearing.

As for hematocrit, the values generally vary from 20 to 35% and do not exceed 50%⁶. In this study, hematocrit ranged from 22.38 to 32.60% for C. gariepinus and from 15.26 to 24.38% for O. niloticus. These results were comparable to that reported by Tiamiyu et al.¹². The species influenced the mean corpuscular hemoglobin concentration with a lower value in C. gariepinus compared to O. niloticus. The mean corpuscular hemoglobin level was not influenced by blood volume or the number of cells in the blood, but can only be correctly interpreted when new cells are released with different hemoglobin concentrations.

Total protein and glucose levels were higher in C. gariepinus than in O. niloticus. The difference may be related to species and environmental factors such as temperature. Bittencourt et al.¹⁷ indicates that some fish become hyperglycemic at low temperatures while others are hypoglycemic under the same conditions. Thus, other environmental conditions such as seasonal temperature changes may contribute to the observed variations. However, creatinine, total protein and glucose levels were lower than that reported in C. gariepinus by Okoye et al.¹⁸ and Al-Otaibia et al.¹³. In O. niloticus, mean values for creatinine and glucose were higher than that reported by Hrubec et al.¹⁹.

The correlation between blood and biometric parameters of fish suggests that these parameters may be strongly, moderately or weakly related positively or negatively and are determined by their size or weight. In contrast to studies by Sahan et al.²⁰ the results of the present study showed a statistically significant correlation between blood parameters, size and weight. The blood parameters for which a positive correlation was recorded in relation to body weight suggest that the metabolic activity of the fish increases as it develops and vice versa for those that showed a negative correlation. It could also be thought that the increase in blood parameter values may reflect a decrease in body surface area with volume (surface area to volume ratio) as the fish grows.

CONCLUSION

This study permitted the determination and knowledge of mean values for some haematological and biochemical parameters in C. gariepinus and O. niloticus in Ngaoundere in Cameroon. These parameters are of definite diagnostic interest and might permit rational interpretation of the analysis in Cameroon.

SIGNIFICANCE STATMENT

This study discovered that physiological parameters of indegious cultured fish in Cameroon varied with species, size and body weight. This can be beneficial to clinician for acurate diagnostic and fish health check-ups. This study will help the researchers to uncover the critical physiological reference values of indigeneous cultured fish that many researchers were not able to explore.

REFRENCES

1. FAO., 2020. The State of World Fisheries and Aquaculture 2020 FAO Italy.
2. Reverter, M., S. Sarter, D. Caruso, J.C. Avarre and M. Combe et al., 2020. Aquaculture at the crossroads of global warming and antimicrobial resistance. Nat. Commun.
3. Bene, C., R. Arthur, H. Norbury, E.H. Allison and M. Beveridge et al., 2016. Contribution of fisheries and aquaculture to food security and poverty reduction: Assessing the current evidence. World Dev., 79: 177-196.
4. Carine, T.N., 2019. Review on aquaculture research in Cameroon: fish farming. Int. J. Oceanogr. Aquacult.
5. Okocha, R.C., I.O. Olatoye and O.B. Adedeji, 2018. Food safety impacts of antimicrobial use and their residues in aquaculture. Public Health Rev.
6. Kefas, M., K.A. Abubakar and A. Ja`afaru, 2015. Haematological indices of tilapia (Oreochromis niloticus) from lake Geriyo, Yola, Adamawa state, Nigeria. Int. J. Fish. Aquat. Stud., 3: 09-14.
7. Erhunmwunse, N.O. and M.O. Ainerua, 2013. Characterization of some blood parameters of African catfish (Clarias gariepinus). Amer-Eur J. Toxicol. Sci., 5: 72-76.
   
8. Witeska, M., K. Lugowska and E. Kondera, 2016. Reference values of hematological parameters for juvenile Cyprinus carpio. Bul. Eur. Fish Pathol., 36: 169-180.
9. Geffre, A., K. Friedrichs, K. Harr, D. Concordet, C. Trumel and J.P. Braun, 2009. Reference values: A review. Vet. Clin. Pathol., 38: 288-298.
10. Moffo, F., J.P. Kilekoung, D.E. Somn, Y.M. Mfopit and J. Awah-Nduku, 2020. Effect of duration and storage temperature on haematological and biochemical parameters of clinically healthy gudali zebu in ngaoundere, Cameroon. Singapore J. Sci. Res., 10: 190-196.
11. Owolabi, O.D., 2007. The dietary habits of the upside-down catfish, Synodontis membranaceus (osteichthyes: mochokidae) in Jebba Lake, Nigeria. Rev. Biol. Trop., 56: 931-936.
12. Porwal, T., 2019. Blood indices of African catfish (Clarias gariepinus) following dietary administration of talinum triangulare.Int. J. Res. -GRANTHAALAYAH, 7: 185-198.
13. Al-Otaibi, A.M., H.F.A. Al-Balawi, Z. Ahmad and E.M. Suliman, 2019. Toxicity bioassay and sub-lethal effects of diazinon on blood profile and histology of liver, gills and kidney of catfish, Clarias gariepinus. Braz. J. Biol., 79: 326-336.
14. Fagbuaro, O. and O.A. Iwalaye, 2016. Heamatological and serum biochemical profile of Nile Tilapia, Oreochromis niloticus from ERO dam in Ikun Ekiti, Ekiti State Nigeria. Amer. J. Res. Commun., 4: 192-205.
15. Kouassi, A.E., M. Cisse, M. Koussemon, A. Ouattara and G. Gourene, 2019. Changements hématologiques associés à l'infection de Aeromonas hydrophila chez le tilapia Oreochromis niloticus (linné, 1758). Int. J. Bio. Chem. Sci., 13: 434-440.
    
16. Eriegha, O., B. Omitoyin and E. Ajani, 2017. Evaluation of haematological and biochemical parameters of juvenile Oreochromis niloticus after exposure to water soluble fractions of crude oil. J. Appl. Sci. Environ. Manage., 21: 1041-1045.
17. Bittencourt, N.D.L.R., L.M. Molinari, D.D.O. Scoaris, R.B. Pedroso and C.V. Nakamura, 2003. Haematological and biochemical values for Nile Tilapia Oreochromis niloticus cultured in semi-intensive system. Acta Sci. Biol. Sci., 25: 385-389.
    
18. Okoye, C.N., S.O. Dan-Jumbo, O.A. Agina, U.U. Eze and A.F. Udoumoh, 2016. Reference intervals for the serum biochemistry and lipid profile of male broodstock African catfish (Clarias gariepinus: burchell, 1822) at varied ages. Not. Sci. Biol., 8: 437-443.
19. Hrubec, T.C., S.A. Smith and J.L. Robertson, 2001. Age-related changes in hematology and plasma chemistry values of hybrid striped bass (Morone chrysops × Morone saxatilis). Vet. Clin. Pathol., 30: 8-15.
20. Sahan, A., T. Altun, F. Cevik, I. Cengizler, E. Nevsat and E. Genc, 2007. Comparative study of somme haematological parameters in European eel (Angulla anguilla L., 1758) caught from different regions of ceyhan river (Adana, Turkey). Eur. J. Fish Aquat. Sci., 24: 167-171.