If you are going to be pouring your stream of liquid from a container where the level of liquid can be seen (this plastic pitcher made from a makeup cap for instance) you will need to determine the angle the pitcher will be held at, and how the liquid will should appear inside the container as the pour is taking place.
Set up your container at the correct pouring angle, holding it in place with a bit of modelling clay or blue tack, and use the syringe or another tool to place your colored glue or medium into the container. Use a damp microbrush, or damp paint brush to clear away any medium that gets on the wrong part of the inside of the container. If you want to show a fairly full container being poured, you will need to build the medium layer in stages, roughly 1/4 of the depth required each time, allowing the medium to dry thoroughly between stages. Otherwise shrinkage may destroy the effect you hope to achieve. Your stream of liquid should not build up to a thick line above the spout. Leave adding medium to the area around the spout until after you have the main layers of liquid built up. Look at how liquid pours from a full pitcher, from a partially full pitcher. The liquid doesn't overwhelm the spout.
To create something that looks like it has just been tipped over to pour, make sure you add a very thin layer of your medium to the bottom or upper side of your pitcher, showing how the liquid has just now been tilted. Look at photographs or watch carefully the next time you pour a liquid out to see what happens.
Your section of fishing line should have a thin line of dried colored medium coating it similar to the one in the photo before you proceed to the next step. Don't worry if your stream of liquid looks to uniform, or too thin at this point.