After completing the course MAR 370 ¿Fish diseases - water quality¿), the students should have a thorough understanding of critical factors related to water quality in aquaculture, and how these influence on health and welfare of farmed fish. The students should know what factors limit fish production in a system, and should have insight into practical and technological solutions to treat water and improve water quality, both in freshwater and marine culture. Integrated in the understanding of the environmental factors, the students should have insight into the physiological reactions of the fish to sub-optimal environmental conditions (patho-physiology). Through writing and presentation of an essay the students should obtain deeper insight into a selected topic, and gain experience in the skills of presentation of a scientific question to fellow students.