I was also out yesterday on Rotoiti with a friend and his young daughter that had never caught a fish before.
Early start from Hinehopu and fished around that area and the bays on the northern side from there.
Water was very warm at the surface, starting at 20.4 degrees at 7am and getting to 21.7 by 11am. Lots of fish very deep as a result and the thermocline was between 15-20m in most area's. Fish seemed concentrated in certain area's in the morning but seemed to spread out later on in the day
If fish weren't on the bottom they were mostly between 25-35m, some just above/below near the thermocline. We had great results using the downrigger at 25-30m and managed to get 3 x 55cm hens for the young lady (i think she's hooked if you'll pardon the pun). Fish were in great condition - between 4.5 and 5.5 lb, and we managed to hook another with 7 colours of lead line out with the lure somewhere in/near the thermocline.
Black/gold tassie and pink frog seemed to have good results, finished by midday.