If your tilapia are free swimming in a lake or pond, netting will be the quickest option to catch them. You can of course use a fishing pole and reel if you are only planning to feed one and you feel lucky.
The size of net you will need will be dependent on the area you need to cover and the depth of your water and the size of the fish you are wanting to catch.
The method we used was shown to us by locals here in Brazil They encircle the area, kicking the shallows to heard the fish to deeper water. They in essence corralling the fish. The fish begin to panic, and when they swim away from you, they get caught in the net where they will stay until you remove them. The net should not be tight otherwise instead of the fish swimming into it, they bounce off as though it were a trampoline.
The gauge of net has to be strong enough to catch the bigger fish. The spaces in the net or the openings need to be the correct size in order to catch them at the gills. You are not wanting to scoop the fish out, you are wanting them to get caught or embedded in the net.
It is a good idea to have a variety of sizes of nets. We have about 5 different ones.
This will allow you to catch the big fish, and the others can stay and grow.
There will of course be different sized fish caught in your net, but you can make the judgement call to keep them out or return them to the water.
The easiest way to remove the fish is to put your thumb into the mouth and your index finger in through the gills. These are forming a ring. If you keep this secure, your fish won't be able to move. Use your other hand to pull the net off the tilapia. You will want to pull the net towards the tail otherwise it will get caught on the fins and scales.
You may find that the tilapia has twisted itself in the net. When they are caught, they will often thrash about and become so tangled we have had no choice but to cut them free and repair the net afterwards.
Depending on the depth of the water you could pull them closer to the shore in order to remove them. This makes it much easier on you.
One thing I would definitely suggest is wearing gloves! The mouth of the tilapia is serrated and removing one or two fish isn't a problem but after that the skin, which is soft from being in water, will become very sore and red.