Hi Tim, welcome to the forum!
I use small plastic containers like sour cream, or chip dip comes in. I run the containers through the dishwasher before using in the fish room. I fill the container about half full of water from the tank the fish are in, then I net the fish and put them into the container. I then float the container in the tank the fish are going into and add small amounts of tank water every few minutes until the container is full. At that point I simply release the fish into the tank by turning the container on it’s side under water.
Best of luck with your breeding project!
Dennis