Many times plecs & nets don't mix. They get stressed, the spines go out, & they get hung in the net. I've spent time untangling plecs from nets underwater, it's more stressfull than just grabbing them. Last experience was when I was in a hurry, netted a female albino bristlenose, & ended up with a 10 minute underwater wrestling match, with me getting spiked a few times.
The trick I usually use for smaller plecs is to get a clean glass jar, insert some zuccini with a weight, and sit back for a while. Within an hour they are in the jar munching away, just remove them jar & all.
With a larger plec, like the 15" common I got this weekend as a freebie, get a pair of leather palmed work gloves. Drain the tank down to a few inches of water, and grab them just behind the eyes, before the muscular tail.