Is Crystal Creek good for brown trout?

Yes, on the classification rather than on a thermometer. WDNR has stocked brown trout into Crystal Creek across 2 recorded plants, between 2015 and 2017, and this site reads the water as cool from WDNR's management tier for it, which is an inference from how the fishery is managed and not a temperature WDNR publishes — but no USGS gauge on this river reports water temperature, so this site has no measured July mean to hold against the 54–66 °F band this fish wants. That is a stocking record and not a survey: it says WDNR put the fish in, not that anyone has since found one holding over. Fish of 8–16 inches are what Wisconsin reports as typical.

Open Crystal Creek on the map See Crystal Creek on the live map → Every reach coloured by water temperature, with the public land and access points along it.

What the state's records say

Species: Brown trout (Salmo trutta)
In Wisconsin: introduced
Record here: stocked — no survey record on this water
Holds in: 54–66 °F, stops feeding above 75 °F
Typical: 8–16 inches
Spawns: Late October into December, on gravel riffles, later in the season than the rainbow and overlapping the brook trout.

Introduced in the 1880s and now the fish most driftless spring creeks are managed for, reproducing without help across most of that footprint.

Is the water cold enough

No USGS gauge on this river reports water temperature, so there is no measured July mean to put beside the species' band. WDNR publishes no temperature classification for this water; the Cool band above is inferred from its management tier for the fishery, and it is not a thermometer.

Gauge	Now	July mean
FOX RIVER AT BERLIN, WI	66.4 °F	78.7 °F

What you may keep

Wisconsin DNR classifies this water as Class III. The management tier on those reaches is stocked. This is a designation of the fishery and not the season and creel rules.

WDNR trout stream classification → Wisconsin season and creel rules →

What to fish for it

Fish Eggs — October–January and April, #10–16
Little Brown Stonefly — February–April, #12–16
Blue-Winged Olive — March–May and September–November, #16–22
Blackfly — April–June, #18–22
Cranefly — April–June and September–October, #6–10
Grannom — April–May, #14–16
Green Rock Worm / Green Weenie — April–June and September–October, #10–14
Hendrickson — April–May, #12–14

The insects recorded from this river's region, earliest first. The full calendar →

More about Crystal Creek

Crystal Creek — live water temperature, regulations and access