Aquaculture Studies
2020, Vol 20, Num, 1 (Pages: 55-64)
Characterization of Nematode Infestation on Parachanna obscura (Gunther, 1861) (Channidae) and Infection in the Blood
Paul Onu Ajah 1 ,Efio-Okon Bassey Ita 1 ,Nneka Love Allison 1
1 Faculty of Oceanography, University of Calabar, Calabar, Nigeria
DOI :
10.4194/2618-6381-v20_1_07
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Parachanna obscura commands high food value and quite critical in the control of
tilapia population in ponds. The health status of fish is assured upon proper diagnosis
of the blood parameters. Research on fifty P. obscura from Great Kwa River, Nigeria
investigated, showed 24 (48%) were infested with nematode and infected the blood
while 26 (52%) were not. The mean blood Pack cell volume (PCV), Lymphocyte,
Monocyte, Leucocyte, Neutrophils, and Eosinophils for infected(non-infested) P.
obscura respectively were 20.8% (21.6%); 44.4% (39.3%); 1.9% (1.92%); 4.18x103mm-
3(4.48x103mm-3), 51.7% (57.5%). and 1.58% (1.2%). No positive correlation existed
between infested and non-infested. The lower PCV, Leucocyte, and Neutrophils are
indications of lower immunity. Prevalence rate increased with size from 26% (22-
26.9cm), 56.5% (27-31.9cm) to 66.7% at class range 32-36.9cm, while Incidence of
infestation decreased with increase in length, 2.75, 2.25 and 2.0 respectively for 22-
26.9cm, 27-31.9cm and 32-36.9cm. The class 12-16.9cm did not follow any pattern.
The parasitic burden occurred at the weaker/more vulnerable part-anal pore (61.7%),
followed by fish intestine (29.8%), cardiac (4.3%) and caecum (4.3%). The mean
physicochemical parameters of the study area across the three tidal intervals ranged
from 5.11±0.04-6.72±0.00 for pH, conductivity 18.70±0.20µS-37.95±1.05 µS, dissolved
oxygen 2.60±0.00 mg/l- 4.00±0.60 mg/l, temperature 25.50±0.50°C-27.00±0.00°C,
salinity 0.01±0.00mg/l-0.03±0.01mg/l and total dissolved solid (TDS) 23.19±0.25mg/l-
47.06±1.30mg/l.
Keywords :
P. obscura, Prevalence, Haematology, Aquaculture, Nematode, Fish healt