What do muskrats eat, as I would like to encourage them to inhabit my pond?

Muskrats, like all animals, require food, water and shelter. If muskrats occur in your part of the country, there are a few things you can do to entice them take up residence. Since muskrats are primarily herbivores, plant natural foods, such as cattail, pickerelweed, bulrush, smartweed, duck potato, horsetail, water lily, sedges, willows, and other aquatics and riparia species. Be sure to plant only species native to your area.

Planting crops adjacent to lakes and ponds can also help. Crops such as corn, soybeans, wheat, oats, grain sorghum, sugarcane, and rice are good choices. It is not uncommon, however, to see muskrats subsisting primarily on upland vegetation such as bermuda grass, clover, johnsongrass, and orchard grass where it “volunteered” or is planted around farm pond dams.

Muskrats also feed on crayfish, mussels, turtles, frogs, and fish in ponds where vegetation is scarce. In geographical areas where the aquaculture industry is important, this feeding habit should be studied as it may differ significantly from normal feeding activity and may cause significant economic loss.

Resources: (online)