Evaluation of the Effectiveness of Garlic Allium sativum Extract against Argulus sp. Infection and Hematological Responses in Goldfish Carassius auratus

Abstract

Background: Infection by Argulus sp. is a significant issue in the ornamental fish industry, particularly for goldfish (C. auratus) because it can lead to tissue damage, haemorrhaging, stress, reduced appetite, secondary infections, and mortality. Current treatments for fish diseases frequently rely on synthetic chemicals and antibiotics, which carry risks of environmental pollution, residue accumulation, and increased pathogen resistance. Garlic (A. sativum) extract contains active compounds, particularly allicin and organosulfur compounds, that possess antiparasitic, antibacterial, and immunostimulant properties, making it a potential natural treatment alternative. However, the effectiveness of garlic extract in controlling Argulus sp., and the concentrations that are safe with respect to the physiological responses of goldfish, have not yet been comprehensively evaluated. Objective: This study aimed to evaluate the effectiveness of garlic (A. sativum) extract in controlling Argulus sp. infection in goldfish (C. auratus), determine the optimal dosage, and assess its effects on fish health parameters, including haematological responses. Study Design: The experimental study employed a completely randomised design (CRD), consisting of five treatments and three replicates. Place and Duration of Study: The research was conducted at Aquaculture Laboratory C in Building 4 (Joint Fisheries and Agriculture Building), Universitas Padjadjaran, Jatinangor, Indonesia, from January to June 2026. Methodology: Goldfish naturally infected with Argulus sp. were used as test subjects. Garlic extract was prepared by maceration with 96% ethanol, followed by evaporation. An initial LC₅₀ test was conducted to determine a safe concentration range for the extract. Based on the LC₅₀ value of 11.06 ml/L (221.2 ppm), five treatment groups were established: A (0 ppm), B (1.25 ml/L or 25 ppm), C (2.5 ml/L or 50 ppm), D (5 ml/L or 100 ppm), and E (10 ml/L or 200 ppm), each with three replicates. For example, the 5 ml/L treatment was derived from a 20,000 ppm stock solution as follows: 20,000 × 5/1000=100 ppm. The fish were maintained under controlled conditions, and the garlic extract was administered via immersion. Parameters observed included clinical signs, haematological responses, survival rate, red blood cell count, white blood cell count, leukocyte differential, and water quality. Results: Preliminary toxicity tests indicated that garlic extract showed antiparasitic potential against Argulus sp. while maintaining fish survival at the tested concentrations (200 ppm). The study results demonstrated that the administration of garlic (A. sativum) extract had a significant effect (P<0.05) on mortality, erythrocyte count, leukocyte count, lymphocyte percentage, and monocyte percentage in goldfish (C. auratus) infected with Argulus sp., whereas it did not significantly affect the neutrophil percentage (P>0.05). Treatment D (5 mL/L or 100 ppm) yielded the best response, characterised by the lowest mortality (36%), the highest erythrocyte count (1,282,450 cells/mm³), a leukocyte count of 107,800 cells/mm³, the highest lymphocyte percentage (77.67%), and the lowest monocyte percentage (14.33%). In addition to improving haematological parameters, Treatment D also resulted in clinical improvements, evidenced by increased responsiveness to feed and tapping stimuli, reduced infection-related lesions, and an accelerated recovery process. Duncan’s post-hoc test results indicated that Treatment D elicited a superior response compared to the other treatments across the majority of the observed parameters. Conclusion: Administering garlic (A. sativum) extract at a dosage of 5 mL/L (100 ppm) proved optimal for controlling Argulus sp. infections in goldfish (C. auratus); this dosage resulted in the lowest mortality, increased erythrocyte counts, improved leukocyte profiles (by raising the percentage of lymphocytes and lowering that of monocytes), and accelerated the recovery of the clinical condition of the fish. In contrast, lower dosages failed to elicit optimal immune responses and antiparasitic effects, while higher dosages (10 mL/L or 200 ppm) caused high mortality (100%).