The adventures that offer Koi Scale special voyages are the Architect and the Trapper. Their scale voyages also reward pearls. The Architect's voyages reward more scales while the Trapper offers more pearls. Also, Architect/Missionary and Trapper/Assassin joint voyages can reward scales, the former focusing more on scales than pearls. The maximum amount of scales a player can store at one time is 250. Any successful voyages after this will not increase the total.