Rainbow Trout

Rainbow Trout
Oncorhynchus mykiss

Key Distinguishing Markings:

  • Rainbow coloration varies widely. The same batch of rainbows grown at two different hatcheries can have noticeably different color intensities and patterns.
  • For the most part, Maryland rainbows have a greenish silver back and a silver sides with a faint red band that travel the length of the lateral line.
  • They are heavily spotted along the sides and top to include the dorsal and tail fins.


  • The average size range of rainbow trout is 10-13 inches, with some individuals reach 20+ inches


  • Rainbow trout were transplanted to Maryland from the West Coast of United States.
  • They are native to the Pacific slope from the mountains in northern Mexico through the western United States around Alaska and the Bering Sea to the northern regions of Asia.
  • They have been introduced into every state in the Union as well as introduced worldwide.


  • Rainbow trout are stocked in well over 100 streams and lakes across the state.
  • A naturally reproducing population is also found in Garrett County's North Branch Potomac River downstream of the Jennings Randolph Lake Dam.

Food Preference:

  • Like other trout species, rainbows are opportunistic feeders and consume a large variety of aquatic and terrestrial insects and macroinvertebrates.
  • When stocked in large lakes like Liberty Reservoir and Deep Creek Lake, rainbow trout, unlike brook and brown trout, can grow very quickly strictly on a diet of lake plankton.


  • In their natural range, rainbow trout are spring spawners and rely heavily on meltwater from high mountain snow pack to trigger spawning.
  • In Maryland, far removed from their natural habitats, rainbows may spawn sporadically and intermittently at anytime between late summer to early spring.
  • Naturally reproducing populations of rainbow trout are found in only three small streams in Maryland.

Fishing Tips:

  • For current recreational size and creel limits, see Maryland's updated regulation page.

Fun Fact:

  • Rainbow trout take well to life in a hatchery as they are fairly disease resistant and easy to rear.
  • Rainbow trout are the predominant trout grown at Maryland trout hatcheries and they form the basis of our successful put and take trout fishing program.
  • Over 500,000 adult rainbow trout are reared annually at State trout hatcheries  and rearing stations.
  • Rainbow trout are stocked in well over 100 streams and lakes across the state.

Family: Salmonidae (Salmonids)

Order: Salmoniformes  (salmons)

Class: Actinopterygii (ray-finned fishes)

For more information on rainbow trout and their management, please contact Alan Klotz - 301-334-8218.

Illustration courtesy of Duane Raver, USFWS

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