Waterlife Octozin 80 Tab Octozin is a treatment for internal parasites such as those which cause sleeping sickness, hole - in - the - head, seawater angelfish and clownfish disease, malawi bloat disease and also early stages of dropsy. Octozin may also be used to treat whitespot in seawater aquaria where cuprazin cannot be used. Octozin is harmless to invertebrates and algae when used as directed. You will require three separate days of treatment to complete the course. Octozin is active for up to 3 days after the last day of use. Although internal parasites are destroyed instantly, external signs of improvement to the fish may take up to 7 days.