Thinking of making fish oil from salmon, how do you harvest the oil that floats to the top in the container?

Skim it out with a ladle
Push the ladle down from the bottom of the "ladle cup" tip the edge in just a little and let the oil creep in, keeping the edge of the ladle just below the surface

You can use bulb baster to draw the top oil off if it is only a small amount. Just try to keep the tip in the oil only. If you put it too far down you will begin to draw the water and any other sludge from the batch.

Years ago we did some ladleing also as Turtledale states, works fine for small batches

We use an electric vacuum pump that we rigged up with a hose attached to drawn the oil from the top of our large bucket batches.

Place the oil that you have drawn into a wide mouth clear glass container. Let it set a few days then you can see if there is any separation between any oil and water.

If there is, you can freeze the container. The water will freeze on the bottom and you can scrape the oil on top off the layer of ice that will have frozen.

It is now pure oil. If you want to really make things easy, put all your drawn oil in a carboy container that has a drain at the bottom. Some you can fit a small diameter hose on it with a pipe clamp.

Fit a plug of sorts into the hose end to stop the flow until you wish to draw the water off. I use an old golfing Tee as a end hose stop. Fits just right. OR

Keep the hose tied up higer on your jug then the oil level volume if you don't want a hose stop on the end. I have done this also.

yep. drain it slow till you get to the top oil