How do male sculpins protect their eggs?

In general, male sculpins are responsible for guarding their eggs until they hatch. While some species shed their eggs loosely so that they adhere to the bottom, others, such as the northern Atlantic short-horned sculpin (bullrout) and the European miller’s thumb, build rudimentary nests that the male then protects.1

Beyond simple guarding, these fish often exhibit territorial behavior and develop distinct breeding coloration to assist in sex recognition during the spawning season.1