October is the spawning peak for Brook Trout in a stream that I monitor in Rocky Mountain National Park. The temperatures lower slowing substantially the snowmelt which decreases silt borne downstream from mountain heights. This lowering of stream turbidity is a huge help when trying to capture the Brookies.
Here is a female digging her nest or redd. She fans her tail, removing silt, sand and other debris from a selected spot on the stream floor, a spot that current will not scour the roe she intends to drop. It takes many attempts before her efforts result in a suitable dig.
The EXIF data does not have selections for the underwater camera used. Thsee images were taken with a Nikon AW1 and 10mm lens. This is a self contained interchangeable lens mirrorless camera that can shoot RAW and JPEG.