Well if I poured cyanide over fish and then caught them with a net, that would count as "net caught". Beware of buying fish that have such low prices unless they specifically state that they didn't use cyanide, dynamite, etc.
See these are different, they were "net catched" not "net caught"
Seriously though, I'm aware, and there really was a big schpiel under the "Net Catched" mess about cyanide and how the fish will last a few weeks until eventually dying. I remember because it also said that a lot of fish used for human consumption are caught using cyanide. Creepy.