Mottled sculpin are very important intermediate predators in native aquatic ecosystems. They prey on small aquatic animals, mostly invertebrates, and form an important prey base for larger fish, such as Salvelinus fontinalis and Esox lucius. They may also help Salvelinus populations through their predation on Plecoptera, which each trout eggs and young. Mottled sculpin are hosts for the larvae of some native clam species, including Anodontoides ferussacianus and Alasmidonta viridis. Mottled sculpin may compete directly with Neogobius melanostomus, an invasive species in the Great Lakes.

Commensal/Parasitic Species:

• slippershell mussel (Alasmidonta_viridis)
• cylindrical papershell (Anodontoides_ferussacianus)