This document provides information on chemotherapy and disease treatment for fish. It discusses the causes of disease in fish, common disease organisms like viruses and bacteria, and how fish are affected by the parasite Diplostomum spathaceum. It outlines important considerations before treatment, such as water quality testing and ensuring the health of fish. Treatment procedures discussed include individual dip treatments, bath treatments of various durations and concentrations, swab treatments, and flush and flow-through treatments added to tanks or ponds. Precautions for safe handling of chemicals are also described.