I have a night light in my pond and the FHM are attracted to it as well as the CNBG/BG/LMB. They will also train to come to fish feed. I see them quiet well in my forage pond where I have just FHM and a few GC. I can't see them in the bigger pond at feeding time because of the rucus from the bigger fish. I started seeing the eggs and fry from my FHM before I started seeing the minnows. Look under floating logs/sticks/etc. They attach their eggs underneath submerged objects. A plastic chair blew into my pond and had eggs attached to it in several places after being in the water for just 3-4 days. I have also noted that they swim in schools. I am no expert, these are just observations. They are there, just give them time.
