These hatcheries are located on the rock formations near the beach of Colònia de Sant Pere. Built in the early 20th century, there were used to keep fish alive for later sale or to use as bait. The hatcheries are partially built on the sea with local materials and sandstone. These constructions are a hundred meters away from each other and feature a circular floor plan with mortar and a concrete circular vault. Through the sandstone doors the visitor will find a square receptacle for the fish.