Parasites are one of the biggest problems affecting fish health, Trichodina sp being the most common in the early life stages of the red tilapia Oreochromis sp. The objective of this study was to evaluate the efficacy of pharmacological and homeopathic substances in the control of Trichodina sp in red tilapia larvae at the Centro Experimental Piscícola (Antioquia, Colombia). In total, 300 red tilapia larvae in the reversion phase (80 observations/larva) were used and distributed in 15 aquariums, each with an effective volume of 63 L. At 0 and 48 hours, two homeopathic substances were applied (garlic [Allium sativum] and ginger [Zingiber officinale], 5 mg/L each) and two pharmacological substances (metronidazole and albendazole, 10 mg/L each) and a control group. The larvae were sedated and the number of Trichodina sp was counted at 0, 48 and 72 h using an optical microscope (4X objectiv...