The Biohut is an artificial fish nursery meant to equip port infrastructures such as docks, pontoons or dikes. By providing food and shelter to the young fish, it restores the ecological nursery function that was lost when natural shallow coastal water were turned into urban environment. The Biohut reproduces the nursery function by a two-cages system: the inside cage is filled with empty oyster shells where a great variety of algae and tiny crustaceans will attach, providing food to the small fish, while the two empty cages around provide protection as their mesh size only allow the small fish to enter, keeping their predators outside.