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stains in the glomerulus. The medullary area also appears highly congested and haemorrhagic (Figure 11; Figure
12). The skin section of the control group showed a normal architecture of a skin structure with no visible lesion.
Also, the melanin is well expressed with no abnormalities (Figure 13). Visible lesion were not found in the skin
section of
C. gariepinus
exposed to 2, 3 and 4 mg/L selenium (Figure 14; Figure 15; Figure 16) but little
histological damage were seen in groups exposed to higher concentrations 5 and 6 mg/L of selenium (Figure 17;
Figure 18). This damage was majorly skin lesion and eroded epithelia surface which changes the normal
architecture of the skin structure. Table 1 shows the water quality parameters, dissolved oxygen decreases with
increase in concentration of selenium. However, all other parameters shows no significant difference.
Figure 1 Gill structure of the control group shows no fisible
lesion ×400
Figure 2 Gill section of
C. gariepinus
exposed to 2 mg/L of
NaHSeO
3
shows stunted secondary gill lamellae ×400
Figure 3 Gill of
C. gariepinu
s esposed 3 mg/L of selenium
shows lamellar necrosis and lamellar hyperplasia ×400
Figure 4 Gill of
C. gariepinus
esposed to 4 mg/L of selenium
shows hyperplasia and haemorrragic of the secondary gill
lamellar ×400
Figure 5 Gill of
C. gariepinus
esposed to 5 mg/L of selenium
shows lamellar necrosis and lamellar hyperlasia ×400
Figure 6 Gill of
C. gariepinus
esposed to 6 mg/L of selenium
shows lamellar necrosis and lamellar hyperplasia ×400
