When infested with sea lice and parasitic crustaceans, commercially farmed salmon are notoriously susceptible to infection. But treating the fish is tricky without flooding the water with chemicals that can contaminate local waters.
Hariolf Schmid of Germany proposes herding the fish into a narrow passage that contains a shallow section which they can only pass through with their dorsal fins sticking out of the water. An automatic syringe then injects a controlled dose of medicine into each fish as it passes (US 2003/0158260). If the farm is too small to warrant this automation, “fish nurses” sitting by the shallow water…
