Monofilament line / nylon lines for trout fishing
The most often used main line for trout fishing is nylon line, also called monofilament line. Nylon lines are relatively unvisable under water for tout and pretty strong. Next to that, it is the cheapest line available. Another advantage of nylon is that it is stretchy. Nylon has a high stretch power which can become in handy during high pressure moments, like during the drilling of a trout. But when you want to feel every little nibble a nylon line is not recommended, but a braided line is.
Of course we will not show nylon lines on this page which will not be suitable for trout fishing. But there is still a difference between the trout lines. To give you a first indication we advice you to have a look at the strength, it should be between 2.5 and 6 KG. Of which the high quality brands have a higher strength with a low diameter. After that you look at the diameter. The diameter should be between 0.14 and 0.22mm. The strength and the diameter are both dependent on the casting weight of the rod and the size of the trout you are fishing for. The 6 KG strength is especially for very large trout. The 2.5 KG is more suitable for smaller trout in trout ponds.
In short, nylon is a nice, almost invisable line which is important, but it is not as thin as you want.