Abstract:
This study was carried out to determine the anaesthetic effects of ethanolic extracts of nutmeg
powder on C. gariepinus. 250 healthy fingerlings ( 25.20 ± 0.03g ) were exposed to five varying
test concentrations (1ml/ L, 2ml/ L, 3ml/ L, 4ml/ L and 5ml/ L of ethanolic extract of M. fragrans
under America standard bio-assays procedure. Indices such as water quality parameters (pH,
Conductivity, Dissolved oxygen and conductivity), haematology parameters (PCV, Hb, RBC,
WBC, MCV, MCH and MCHC), histology examinations (gills, liver and kidney), behavioural
responses and LC 10 were observed and recorded. Data collected were subjected to Analysis of
variance while the median lethal concentration was determined using Probit analysis. The effect
of ethanolic extract of M. fragrans increased with increase in concentration; the induction time
decreased while the recovery time increases. The experimental fish displayed rapid opercular
movement, erratic swimming, hyperventilation and loss of reflex during exposure to ethanolic
extract of M. fragrans at different time duration as concentration increased. The temperature, pH,
Dissolved oxygen and conductivity in the experimental tanks showed no significant difference
before induction but there was significant difference (P<0.05) after induction (introduction of
extract). Blood parameters (PCV, Hb, RBC) showed a decreasing trend, WBC showed increasing
trend while MCV, MCH and MCHC were sinusoidal across treatments. Histological examination
of the gills showed normal gill architecture (1ml/ L – 3ml/ L) while slight alteration of normal gill
rakers, inflammation and swelling of the lamellae were observed at 4ml/ L – 5ml/ L; kidney showed slight hyperplasia of Bowmans capsule (1ml/ L- 3ml/ L) while lymphocytic infiltration,
vacuolation, inflammation and necrosis were observed at 4ml/ L – 5ml/ L; Liver showed normal
architecture (1ml/ L – 3ml/ L) while inflammation, hemolysis and hepatocytes degeneration were
observed at 4ml/ L – 5ml/L. LC 10 obtained after 72hrs was 6.50ml/ L. Mortality of the test fish at 1ml/ L- 4ml was 0% while at 5ml/ L was 10%. Thus, this study revealed 3ml/ L safe level as
anaesthesia with total recovery potentials. Therefore, ethanolic extracts of M. fragrans is
recommended as anaesthesia for fish during handling operations such as transportation, sorting,
weighing, surgical operations and also during treatment for disease.
