Trout reproduction

---

Though there have been sporadic instances of rainbow trout spawning in Iowa, only brown and brook trout reliably spawn and reproduce here. These trout are the only Iowa fish that spawn in the fall, generally October and November.

Trout construct a spawning nest or redd, a depression excavated into the stream bottom by the fish. Redds are very visible in the fall in areas of very clean gravel, good water flow and well-oxygenated water. Public and private efforts to stop soil erosion help protect such spawning areas.

Trout eggs hatch in February through early March. The trout fry that emerges from the egg is only about 3/4 of an inch long. They grow to 3-5 inches by the end of their first year and up to eight inches long after two years. Brook trout are short-lived, reaching a maximum size of about 16 inches at four or five years old. However, brown trout can attain a 25-inch or even larger length in Iowa streams.