I think highly saturated pinks and purples in the flowers with yellows and oranges in the middles of the flowers with yellow being a radiant light source. Blue in the koi will work very well. The important thing in this situation is that you have to be very open to what an artist might suggest when it comes to color.
agree with David, was going to suggest exactly the same, pinks and purples for a lotus flower with yellow centres blue on the koi as he suggested will also go very nicely with this palette. whatever you choose to do just make sure you post lots of pics so we can see it.