Jungle Perch
Japanese Name: Ookuchi Yugoi/Mikiyu (Lukian)
English Name：Rock Flagtail / Jungle Perch
Scientific Name：Kuhlia rupestris
Freshwater predator that only live in tropical islands of Japan and Asia Pacific that can grow up to 45cm. Mostly living in freshwater, but become coastaly anadromous for spawning season why they migrate from island to island.
Similar to both freshwater bass and mountain river charr that feeds opportunistically on insects, crustaceans, and even fallen seeds. Very aggressive feeder yet, on a contrary, very wary fish who hide tighly under rocks.
Spring to autumn are the best season even for dry fly while winter season demands using tightline nymphing technique.
The fish I spotted while riding on rental scooter on Chichi Island in Ogasawara Archipelago in a small river by a village house had gone away when I parked the bike 5m away. Same fish came back on my way back who don’t spook on trucks passing by but it spooked a second when I pulled over the bike.
When found mixed with Nile Tilapias, Jungle Perch are the first one to finish rising and hide somewhere.
Fly Tackle & Line System
Dry Fly
Singlehand 2-4wt 6-7ft with floating fly line made for mountain river trout dry fly providing the accuracy and the reach you need to challenge this wary fish. See white-spotted char who are very similar character.
Tapered leader the same length of rod plus long tippet to buy time for natural drift.
Nymphing
Singlehand 2-4wt 10-11ft with Euro nymphing set up gives your more access to this fish even in bad weather and cold season. Length really helps to present nymph without exposing your presence too much.
Fly Selection & Presentation
Vareity of fly patterns designed for mountain river trouts are the best match.
Jig nymph gives more access but you need both natural colour as imitation and attractor types to urge hiding fish to come out.