For info on fishing gear and what to use to boost my fishing skill, I went to El's Extreme Anglin' (equipment page)
. Lots of good information there!
When catching the carps, I used a +30 fishing pole, Weather-Beaten Fishing Hat
, Captain Rumsey's Lager
, and some lures. There's also an item
you can equip, use, and then unequip to get a small boost in fishing for 2 minutes.
Sidenote, 700+ fishing is not
absolutely necessary and it's hard to confirm if having higher fishing actually does help or not. I've heard of cases where people with less than max fishing managed to catch the carp pets (from open water) without too much hassle. It's all up to each person to decide if they feel the fishing skill boosts are worth it or not.