October is the peak spawning time for Brook Trout in this high mountain stream in Colorado.
The female Brookie is in the front, treading water over her redd.
Here the female fans her tail digging her redd or nest. This provides a hollowed out place in a stream bed that will not be scoured out by the stream's current. Into this redd she deposits roe, then the males come, fight and deposit milt. Silt then covers the fertilized eggs providing protection until they "hatch" and move downstream.
I just lay on the bank and reached out submerging my Nikon AW1 camera with 10mm lens guessing at the framing and fired away. Sometimes it surprises you what you end up with.
Underwater photography is fun!