You can bait fish in multiple spots in runescape. The most popular one's I know is:
Free to Play area's
1. South of Lumbridge ( where the fishing tutor is) 2. Karajma Dock's (take a ship from Port Sarim to Karajma) 3. Draynor Village Fishing spot (next to the willows) 4. Barbarian Village (next to the Stronghold of Security)
Pay to Play area's
1. Catherby (search the name on map to find a fishing spot) 'look for fishing symbol' 2. Tree Gnome Village Stronghold 3. Shillo Village 4. Ardougne river
1. Fishing Rod (can be bought at the Grand Exchange) 2. Fishing Bait (can be bought at the Grand Exchange)
Every time you catch a fish, you will lose 1% of you bait each time. Good Luck fishing!