These can be used in the Lu Shang's Fishing Rod quest as well as moat carp. However the NPC pays you more for these than moats. 10gil each Moat carp. 20 gil each Forest Carp.
Fishing Level 46 with a Lu Shangs + insect balls, no fishing skill help/or gear/or fishing enchantment or boosts. Nothing. Warp to Elshimo Uplands, the Yhoator Jungle at I-7, the little round pond called Bloodlet Spring. Fished up 75 fish for RoE - and 3 stacks of it was Forest Carp with this set up. You can buy cheap insect balls at M&P Market in Kahzam if you need them. Very easy to fish reel in. They don't fight.
