I live in brook trout heaven. The limit is 20 brook trout of any size. 90% of the waters in my area contain only one species of fish.....brook trout. No other species of fish or minnow live in these waters. Yes, there are some waters where chub or suckers have been introduced due to stupidity and in these waters, the trout population is automatically reduced by 40 to 60%.....and this is without any fishing pressure. Many of the brook trout waters in my area never see a fisherman. Most will see a couple of fishermen per year. Since there are no other fish for the brook trout to feed on, they eat insects. Fly fishing is fantastic all summer.
So imagine your favourite brook trout lake and imagine how many brook trout would be in this lake if there were no minnows and no fishing pressure. That's what it's like where I live in Northern Quebec.
I have often tried brook trout fishing at night and I have very rarely caught anything. I've seen thousands of brook trout feeding at the surface of lakes but as soon as it gets dark, it's as if there were no fish in that lake. However, there are no insects on or near the surface of the water either.
So I guess that if minnows are the brook trout's natural feed, I guess they do feed at night and can be caught at night. Different story for the brook trout where I live. On top of that, during the summer up here, it gets dark around 11 pm and the birds start singing at 2:30 am.