This rarely happens--Round Valley Reservoir frozen enough to ice fish, let alone frozen at all. But this was last year. All this week temperatures have climbed over 50, usually well over, yesterday felt like 65. The reservoir, as deep as it is, retains enough heat to provide shoreline trout fishermen a winter of recreation, usually, and this winter I'm sure will be one of them.
But the likelihood remains for some ice, and the best ice fishing, in my experience, is before any snow gets on it. Some ice fishermen are so eager for opportunity, I guess particularly during a winter when much isn't likely, that they go out with marginal safety. If you're a beginner, my best advice is to find a reliable someone who will take you out without risking your life. The Knee Deep Club of Lake Hopatcong is a good one to join for more reasons than this one alone. The larger lakes don't freeze evenly; you need to always know how thick the ice is you will traverse.
Bad days for fishing are best. Those bluebird days with abundant sunshine penetrating fresh, clear, snowless ice down through clear water make a beacon of shiner scales below tip-ups, and chrome spoons fished on jigging rods. Largemouth, pickerel, northern pike, hit in reaction. In fact, only under such black ice/blue sky conditions have largemouth--a number of them--taken a shiner, run perhaps five yards of line from a tip-up, and dropped the bait. These fish didn't care to feed. It was aggressive reaction to the flash of the shiners. Otherwise during winter ice fishing, a bass takes a shiner and would probably run all the line off the spool if it wasn't attended to.