Scoop nets are round, flat handling nets used to catch and control koi of all sizes. Scoop nets come in a large variety of sizes and net material. Pan diameters from 33 to 100 cm with handles from 105 cm to 270 cm. 

It is very important that the net material and mesh match the requirement of the koi and does not cause damage, especially to the fins

Never use a net made of a knotted material.
Choose mesh size for ease of use.
Use a waterproof sock net to prevent fin damage while using a scoop net

Net size 8.5 mm square. (15 mm stretch) is about the limit you should use for koi..