Close-ups are generally more interesting. You'll see your Koi's eyes shift, look at you and wink as they swim by or stop to beg for a treat. You'll glow with pride when you see your Sensuke Kohaku's straight, sharp, beautiful Kiwa up close. If yours has an optional manual white balance, hold a white piece of paper in front of the lens near your pond and get a white balance. This will help ensure the colors are accurate.
Glare is always a problem when shooting ponds.
Sunny days with clear blue skies will offer the best results. Cloudy or overcast skies cause heavy glare. A polarizing filter will help fight glare but only if you are locked down on a tripod. When you try to move the camera the polarizing effect will change also. Shaded ponds tend to photograph well if you shoot in only the shaded areas.