Efficacy of garlic juice and lemon juice as bio-product treatments for Ichthyophthirius multifiliis (ich) infections of juvenile Nile tilapia, Oreochromis niloticus

Abstract

The ciliated protozoan, Ichthyophthirius multifiliis, has a worldwide distribution and almost all freshwater fish species are susceptible to its infection. Both the parasite and the resulting disease condition are popularly called ich. Currently, formalin is the only therapeutant approved for use on cultured fishes to control ectoparasites. However, the high cost and human handling safety concerns restrict the applicability of formalin for widespread use in developing countries such as Malawi. Previous studies have demonstrated garlic juice (Allium sativum) and lemon juice (bioflavinols) as alternative, "safe" treatments to control infestations of I. multifiliis and other parasites, but their efficacy has not been reported from controlled studies. To determine the efficacy of garlic and lemon juice on ich survival, two trials were conducted between July 2003 and September 2004 at the Marine Institute. Juvenile tilapia, Oreochromis niloticus, were infected with ich theronts and treated with different concentrations of garlic juice (1.5 - 3g/L) and lemon juice (5g/L). After infecting the fish with ich, various biological indices (condition factors, specific growth rates, feed conversion ratios, hepatosomatic indices, splenosomatic indices), blood immunology and histology samples were examined weekly for four weeks to assess treatment efficacy. Garlic juice (3g/L) in a continuous static bath exposure was the most effective treatment. Lemon juice (5g/L) was effective in killing ich theronts but resulted in unfavourable water conditions (reduced pH).