Kathy--- I catch BIG koi all the time. When it comes to valuable fish, reducing stress levels on the aminals , and making it easier and faster.... best way is to drain it down quite a bit if possible. Reducing they natural space to flee is vital. Remove all items they will seek for cover like lilly pots, underwater rock covers..etc...
Turn off any waterfalls or aerators for still surface water, less reflections. Try catching when the sun is not beaming down on the water, I find it easier in the morning when the skies are overcast. Less surface reflection.
If you have a good amount of water using a net that can partition the pond, or anything that will act as a barrier will keep them in one area. One time I used a shade cloth to act as a fence. Be ready with bricks, rocks,..etc to weight down the bottom of the net to the pond bottom.
Use a soft thread netting when netting them out. Hard nylon TROUT nets and the like remove too much slime coat and can pop scales.
Move slow.................slow...slow.... SCOOP from underneath, make them move up in the water and right before they crest the water... life em FAST !!
I've had koi shoot out of a net in inches of water.
With big fish I like to work with a team mate. I'll be in to MAIN NET... my bud will use another net to shoo them towards me... once netted... I quickly pass the big fish to my buddy on land for quick transport to holding tank.
Don't freak when your mature females bleed from the gills. Gravid females especially will bleed, as the capilaries in their gill tissue burst. It's another way the females show stress. it's temporary,... no worries.
best of luck !
c
