DAO 84:243-250 (2009)  -  DOI: https://doi.org/10.3354/dao02052

ABSTRACT: The causative agent of tremor disease (TD) in the Chinese mitten crab Eriocheir sinensis has been shown to be a member of the genus Spiroplasma. In the present study, a susceptibility test indicated that oxytetracycline (OTC) has both a high degree of efficacy in the inhibition of Spiroplasma and a broad range of safe concentrations. Treatment experiments showed that the best concentration of OTC for use against TD was 40 mg OTC kg^–1 crab weight. Acute toxicity experiments demonstrated that the 24 and 48 h median lethal dosages (LD₅₀) of OTC for this species of crab were 366 and 340 mg OTC kg^–1 crab body weight, respectively, while the safe concentration was 82.5 mg OTC kg^–1 crab weight. We suggest that OTC has potential as a highly effective inhibitor of Spiroplasma pathogens in aquatic animals and has been proven to be a potent, safe and low cost cure for TD. This represents a novel use of OTC in the therapeutic treatment of an aquacultural disease caused by a Spiroplasma pathogen.

KEY WORDS: Oxytetracycline · Spiroplasma · Tremor disease · Acute toxicity · Chinese mitten crab · Eriocheir sinensis