Rainbow Trout - Oncorhynchus mykiss
Habitat requirements and life history: The rainbow trout is an anadromous fish that is native of the western North American continent from Alaska to extreme northwestern Mexico. Virtually all rainbows caught in Massachusetts are hatchery fish that provide a "put and take" fishery wherever they are stocked, with the exception of a few designated "catch and release" areas on selected coldwater streams. The rainbow trout inhabits river, lakes and reservoirs and is frequently stocked in ponds. It requires clean water where temperature do not exceed 70° F. (Sources: Freshwater Fishes of the Carolinas, Virginia, Maryland, & Delaware and Massachusetts Wildlife, No. 2, 2000, Special Fishing Issue)
Total length: hatchery stock 9-12 inches
Pollution tolerance (US EPA): Intolerant
Classification: Fluvial specialist
Number of fish found during 1954 & 2001 Fish Surveys*
| Location | No. of Fish 1954 | No. of Fish 2001 |
| Assabet River | 6 | 16 |
| Great Brook | 2 | |
| North Brook | 3 | |
| Total | 11 | 16 |
*Sources:
DFW. 2001. Assabet Watershed Fish Survey. Mass. Division of Fisheries and Wildlife (MassWildlife), Westborough, MA.
Schlotterbeck, L.C. and W.A. Tompkins. 1954. "A Fisheries Investigation of the Merrimack and Ipswich River Drainages." Bureau of Wildlife Research and Management, Mass. Division of Fisheries and Wildlife, Westborough, MA.
