Toadfishes: Batrachoidiformes

Toadfishes produce sound by contracting muscles on their swim bladder, which is an internal sac that fishes use to control their position in the water. Both males and females produce grunts, but only males make longer courtship calls, which sound like boat whistles or humming.

Male toadfishes prepare nests, usually under rocks or shells but sometimes under objects discarded by humans, such as cans and bottles. Males attract females by making their sounds, and then females lay large, sticky eggs and leave the area. Males guard and fan the eggs until after hatching. Fanning is using the fins to move water over the eggs to clean them and make sure they have plenty of oxygen. The young may remain in the nest after hatching. One species of toadfish has two types of males, larger nest-holding ones and smaller sneaker males that dart into nests attempting to fertilize (FUR-teh-lyze), or place sperm on, eggs of a nesting pair.