Scientists often equate the quality and extent of parental care an animal provides as being one indicator of intelligence - if so, then I would think many of the cichlids would rank well in intelligence, relative to other fish. It is also very possible that intelligence is relative from species to species, and how we measure intelligence may not capture true intelligence among other species. I'm sure many of my fish that come to the front of the tank to be fed everytime I walk by are sure I'm mentally deficient when I only respond to their begging once or twice a day.... 
