each fish was orally administrated with 10 mg kg-1
BW of norfloxacin once daily for 5 consecutive days, to determine
the blood concentrations of norfloxacin in infected fishes. Before
the experiment blood samples were taken, negative control samples
(non-treated) showed no bacterial inhibition, indicating no intrinsic
antibacterial activity of the samples. The experiment was performed
in accordance with the guidelines set by the Ethical Committee of
Benha University, Egypt.