A study of the histology of gill, liver and kidney of Nile tilapia exposed to various sub-lethal concentrations of aqueous extract

Abstract

This work determined the toxicity of Moringa oleifera seed powder to the most cultivable fish species in Africa, 
Tilapia, Oreochromis niloticus, Fingerlings. Moringa oleifera (Moringacaeae) seed powder is a good water 
purifier; it contains polyelectrolytes, which constitute active ingredients in water treatment The 96-h bioassay 
was conducted to determine the median lethal concentration (LC50) for Nile Tilapia, Oreochromis niloticus, 
fingerlings to aqueous extract of drumstick, Moringa oleifera seed. The 24-h, 48-h, 72-h and 96-h of M. oleifera 
applied to O. niloticus fingerlings were 252, 251,242, and 242 mg/l respectively. Toxic reaction exhibited by fish 
includes erratic movement, air gulping, loss of reflex, discoloration, molting, loss of scale, and haemorrhage. 
Haematological examination shows an increase in number of blood cell counts (PCV (%), Hb(g/mm3) 
RBC(106/mm3), MCHC(T/L-), from 17.550.7, 5.70.3, 3.70.1, 1.10.1,31.21.7 in control to 23.04.2, 7.71.5, 
3.90.1, 2.60.3, 34.11.4 in higher concentrations, while there was reduction in the number of ESR(%), MCH (pg), 
and MCV (3) from 121.4, 5.00.9 in control to 91.4, 3.40.9 in higher concentrations in fingerlings tilapia. The 
histological changes in the gill, skin, liver and kidney includes different level of degeneration of cells, lamellar 
hyperemia; hypertrophy of gill arch, Shrinkages and dermal erosion and necrosis of skin, while hyperplasia, 
disarrangement of hepatic cell, necrosis and vacuolation occurred in liver and kidney of fingerling Tilapia 
Oreochromis niloticus. Damages became severe with increasing concentration of M. oleifera to fish and time of 
exposure. There was no significant difference in water quality in the test, the result obtained before the test, 
during the test and after the test were found closed to the water quality parameters of the control. Results of the 
test provide baseline information and established safe limit of using aqueous extract of Moringa oleifera seed 
powder in fresh water pond. It was ascertained that aqueous extract of Moringa oleifera seed powder did not have 
adverse effects on water quality.