one place you can get it is at the catherby fishing store
look here: http://runescape.wikia.com/wiki/Big_net
catheby
The best way to fish on runescape is to use a net or a fishing rod and bait in draynor. Then it is easy to bank your fish
in karamja island (there is no bank there)
Big enough to catch the fish !
The amount of experience depends on the type of fish, not on the type of net. You merely need specific equipment to get certain types of fish.
Lumbridge Swamp Caves, using a small fishing net.
Trawl
No there is no worm in clam water I did my reserch but there is no worm you need to go to soda seas to find the worm you pick up the worm go find the yellow fish named Fluffy he will bite the worm now you can take it and drop it in the net or you can find the big fish also known as the Mullethe will bite Fluffy who is biting the worm you take the fish and put it in the net
same way you do with fish except you need a net and a big boat. :]
Anywhere you can net fish, you can bait fish with a fishing rod, too. That includes the Lumby swamp (at the river), Draynor (at the ocean), Karamaja (on the docks), and the Lumby Pond.
You learn how to fish them in tutorial island...small fishing net, over a fishing spot which says "Net".