Jellyfish has been causing fish farmers both in Norway and abroad an increasing number of troubles in recent years. But what exactly are they, and how are they causing damage to the fish? Last, but not least, what can we do to protect the fish and minimize the harm? To teach us about this we have been fortunate to get a visit from an aquaculture legend all the way from Ireland (but he`s actually Scottish). It`s the one and only Hamish Rodger! With more than 30 years’ experience as an aquatic animal veterinarian we are certain he has a thing or two to teach us about these creatures.