Facinating actually, you say its a dock, well i am guessing its a inland dock with fresh water, since those are all, afterall fresh water fish, but what suprises me, you say the koui dont get close to you, yet those are fairly large koi, and koi, when well established with it surrounding does get brave, because heck koi are the smartest fish around, proven fact, so if you spend hours there, i am suprised the koi havent begun to take a liking to you, and come up close, because koi actually tend to like being touched and stroked...
Also in your picture with the ghost koi, you have a common carp there, not unusal, since wherever you find large open waters you will find common carp...
And with those size fish, i am supirsed that dock aint covered with fisherman, is it private land?
(please note i am a fisherman myself, was one of my most favorite sports until i got half blinded in a fishing accident)
Next time, throw them abit of sweetcorn, it there is one thing i know about koi and the larger spieces of carp, they really LOVE sweetcorn