On an overcast March day in Washington Park, a gaggle of excited children in winter coats crowd around a black bucket filled with writhing, slippery rainbow trout trucked in from Ava, Mo. Minutes later, about 300 of the green and purple fish slide from the truck’s holding tank through a long metal chute and into the park’s upper pond. It’s the 31st year that the pond has been restocked with the 10- to 11-inch trout, says Dan Stephenson, district fisheries biologist with the Illinois Department of Natural Resources, adding that the non-native trout don’t like water above 70 degrees Fahrenheit, so DNR stocks about 70 sites statewide each spring and fall. Trout fishing season opens April 2 and requires anglers to have a valid fishing license and inland trout stamp. Proceeds from the stamp pay for restocking ponds. To buy a fishing license and stamp online, visit www.wildlifelicense.com. For more information, visit www.dnr.illinois.gov.