Intensity of Ichthyopthirius multifilis infection on Clarias gariepinus juvenile 48h pre-treatment with Ocimum gratissimum. Key: A: Normal control (not infected and not treated); B: Negative control (Infected, not treated); C: Standard control (infected and treated with 150mg/L chlomphenicol); D: 500mg/L Ethanolic leaves extract of O. gratissimum (ELEOG); E: 1500mg/L ELEOG.