Fishing in Zion National Park is doable if you have a Utah fishing license, but it is not a hugely popular pastime here. For those who must wet a line, the Virgin River and its North and East forks have four native fish species and five non-natives.
The natives have evolved so they can survive high sediment loads, periodic flooding and a wide range of water temperatures -- conditions that are often fatal to the non-natives. The natives are virgin spinedace (Lepidomeda mollispinis mollispinis), desert sucker(Catostomus clarkii), speckled dace (Rhinichthys osculus), and flannelmouth sucker (Catostomus latipinnis). The virgin spinedace and flannelmouth sucker are both much reduced from their original Virgin River habitat. Both are managed under conservation agreements.
The non-natives include four trout species (Bonneville cutthroat, brook, rainbow and brown) as well as the channel catfish. Only the rainbow trout could be considered common in the Virgin River drainage, while the rest are hard to find.
According to park biologists, the main reason that the natives are doing so well is because the Virgin River has no dams that would regulate its flow and thereby its sediment, flooding and water temperatures. This intact ecosystem protects the natives while keeping the non-natives in check.
The mountains around Zion have stocked reservoirs and plenty of fishing opportunities. On Highway 14, go check out Duck Creek, Navajo Lake and Kolob reservoirs.
In any event, visit the website of the Utah Division of Wildlife Resources (www.wildlife.utah.gov) for fishing opportunities and regulations.