International Journal of Aquaculture, 2018, Vol.8, No.2, 8-16
9
The changes in some serum biochemical indices of farmed
Clarias gariepinus
caused by stress due to exposure to
environmental pollutants, pathogen challenge, or nutritional toxicities have been reported (Onusiruke and Ufodike,
2000; Oladele et al., 2011; Adeyemo et al., 2016). According to Lio-po and Lim (2002) more data is needed for
monitoring of managements and or therapeutic interventions in the culture of this fish species. Hence the present
data would provide useful information for disease diagnosis
C. gariepinus
farmed in earthen ponds in the Guinea
Savanna agro-ecological zone of Nigeria.
2 Materials and Methods
The Southern Guinea Savanna agro-ecological zone of Nigeria lies within latitudes 8°4’ and 11°3’N and
longitudes 2°41’ and 13°33’E (Jidere et al., 2007). For the purpose of this study, the zone was delineated into
three areas (area A consisting of Abuja and environs (9.08°N, 7.40°E); area B consisting of Lafia and environs
(8.51°N, 8.52°E) and area C consisting of Makurdi and environs (7.73°N, 8.54°E). The sampling areas are at least
between 200 km apart from one another. For each area sampled, longitude, latitude, and elevation data were
recorded using a hand-held Global Positioning System device (eTrex GPS, Garmin Corporation, Olathe, KS).
2.1 Selection of samples
A total of two hundred and forty (240) apparently healthy
C. gariepinus
farmed in 24 earthen ponds (ten farms
from each sampling area) were used for the study. Selection of farm was based upon good management/farming
practice pond culture water sauced from a deep bore hole; non use of antibiotics (Langdon and Jones, 2002), and
chemotherapeutic agents accompanied with regular and correct feeding using certified commercial diets; while the
selection of sample fish was based upon an exclusion criteria of weight (250 g ≤ fish ≤ 450 g as juveniles and 451 g
≤ fish ≤ 1000 g as adults) with the absence of lesions and discernible ecto parasites using the method of Stoskopf
(1993). Fish sampling was accomplished between the months of July 2016 and July 2017.
2.2 Collection of blood for serum biochemical analysis
Blood samples for clinical chemistry determination were collected from the caudal vein via caudal veni-puncture
using a 5.0 ml syringe fitted with a 19 gauge needle. About 2 to 3 ml blood per fish were collected into a clean
glass test tube. The blood sample was kept at room temperature for 30 minutes to clot. Afterwards, the test tube
containing the clothed blood was centrifuged at 3000 revolutions per minute for 5 minutes using a table centrifuge,
to enable a complete separation of the serum from the clotted blood. The clear serum supernatant was then
carefully eluted with a clean syringe and needle and stored in an Ependorph tube at 0.0°C for the clinical
chemistry determinations. Biochemical parameters were determined by a semi-automatic chemistry (RT-1904CV,
China) analyser according to the manufacturer’s protocol. Reagents were supplied by Spectrum Diagnostic
(Spectrum Lab, Egypt). The serum biochemistry reference interval was determined according to Friedrichs et al.
(2012), following the guidelines of the National Committee for Clinical Laboratory Standards.
2.3 Statistical analysis
Data were assessed for normality using the Kolmogorov-Smirnov test and confirmed to be normally distributed
(P<0.05). Using the methods of Horn and Pesce (2003), outliers were screened and eliminated when found. The
lowest and highest values measured for each analyst and the 25
th
and 75
th
percentiles were mathematically
determined. The difference in serum biochemical parameters between male and females and between juveniles
and adults were statistically analyzed using appropriate tests with the accepted level of significance set at P
≤
0.05.
3 Results
The mean values water quality parameters obtained from the sampling areas are presented in Table 1. Farms in
Abuja environs had the highest water hardness (168.00 ±10.19 mg/l CaCO
3
), while farms in Lafia area had the
least water hardness (142.39 ±17.04 mg/l CaCO
3
). The dissolved oxygen concentration and water temperature of
ponds in Abuja area are 5.62 ±1.07 (mg/l) and 21.3 ±2.01 (°C) while those for Lafia and environs are 4.97 ±1.91
(mg/l) and 29.60 ±1.65 (°C). The PH of pond water in sampled farms in Abuja, Lafia and Makurdi areas are 7.28
±0.02; 8.11 ±1.05 and 7.78 ±1.04 respectively. The electrical conductivity of the pond water ranged from 296.62
±5.18 (in Abuja areas) to 415.09 ±17.24 (in Makurdi sampling area).
