The player can use a Fishing Rod to fish in them to get Tropical Fish. Shoals can contain a maximum of 10 Tropical Fish, and they spawn with randomly 6 to 10 Tropical Fish remaining. New Tropical Fish are spawned every 4 minutes (half day) if the Shoal contains less than 10. The Shoal's appearance will show less fish if less than 5 Tropical Fish are remaining in it, and it will be invisible if empty. Fishing in Shoals has a 20% chance to spawn Sea Hounds, so caution must be taken.
Shoals naturally alternate between active and inactive periods, each state lasting for a day. They will disperse when they have been active for a day and enter the inactive period, unless they are being fished at the moment that they need to disperse. A day after dispersing, they will regroup and become active. Shoals will also disperse if disturbed by sailing over them. Additionally, Strong Winds and Hail will disperse most of the Shoals in the world, making them unreliable as a food source during the Hurricane Season.