The interesting thing was most of the FHM were eaten after the lights went out in very dark conditions. They would occasional get one or two during the first few minutes when the FHM were intitially introduced into the tank. Basically a FHM would swim too close to a RES and get sucked in from a few inches away, but the RES wouldn't start to chase them around the tank until the lights were about to go out. When the lights were on they mostly just ignored the FHM in the tank. My aquarium RES had a very uncanny sense when the lights would go off every night and would herd the minnows into a ball just under the light about 15 to 20 minutes before the light turned off. Once the lights when out it was game on.
