I'm bored of fishing & want to try a bit of variety.

 

Would Cavefish be an alternative to the other methods (Barb & monks + C2's)?

 

I will be using fishing pots (would rather use Admiral Pie but too much invent space would be used) & Granite Lobbies to try & speed things up a bit.

They would be much better with Call of the Sea I imagine. Nice option if you want to afk while doing school or something.

Well if you want AFK, then yes you should take a look at cavefish. As Paul rightly said, Call of the Sea aura would really help out with the fishing of it.

Don't forget about fishing urns too, if it's the exp you're looking for rather than the profit from the cavefish. 10 of them in your inventory, then a few fishing pots if you still want to use them, then of course your granite lobster pouch, which you should summon just before you start fishing.

Just keep fishing till you've filled up all 10 urns, send them away, tele to a bank (Ring of kinship or Tokkul-zo for quick and free tele) and grab more urns.

Should still be afkable enough with that method

Expect them to be significantly worse than C2 or heavy rod fishing, and more or less on the same level as monkfish (which are not a good method).