You can catch Minnow from one of RuneScape from wangrui's blog

From the northern platform, players can also locate an NPC Kylie Minnow. If you're wearing full Angler outfit, then have 82 fishing and RuneScape gold finished Fishing Competition pursuit she is able to transport you to Minnow grabbing platform. In this area, you can catch Minnow from one of the four places which afterwards can be exchanged for buy OSRS gold Raw Sharks at 40:1 ratio.