Ichthyotherapy is the use of fresh water or marine organisms (mostly Garra rufa) as agents of skin wound/condition cleansing.
This practice promotes itself as a treatment that alleviates symptoms of psoriasis.
One study (and that is the only article I could find about the subject) states in its abstract:"Sixty-five percent [43 subjects] stated that after the relapse their symptoms were less severe than before treatment. There were no significant adverse events. The benefit demonstrated in this study along with the favorable safety profile suggests that ichthyotherapy could provide a viable treatment option for patients with psoriasis."
Yet, the article about the Doctor fish on Wikipedia says the following:"The use of the fish as a spa treatment for the wider public is still widely debated on grounds of efficacy and validity, as the treatment is not shown to have either positive or negative effects."
So, is ichthyotherapy pure quackery or is it a medical treatment in its infancy?
Sources:
Ichthyotherapy - Wikipedia, the free encyclopedia
Grassberger, H., Hoch, W. (2006), "Ichthyotherapy as Alternative Treatment for Patients with Psoriasis: A Pilot Study", Evidence-Based Complementary and Alternative Medicine 3(4), pp. 483-488
Doctor fish - Wikipedia, the free encyclopedia