These six lakes aren't the same kind of fishing. Lake Biwa and Lake Kasumigaura are freshwater bass water, the closest thing Japan has to a Southern U.S.-style lake fishery. Lake Saroma and Lake Ogawara are brackish coastal lagoons — Saroma's water is nearly as salty as the open sea — better known for scallops, salmon, and shijimi clams than bass. Lake Inawashiro, once too acidic for much to live in, now grows record-size smallmouth bass and big trout, and Lake Suwa is a small alpine lake famous for one thing: winter wakasagi from a heated boat. What ties them together is more of a shared habit than a shared certainty: checking moon phase — the major and minor feeding windows anglers have used for generations — is worth doing wherever you're headed, alongside the weather, not instead of it.
Essential Japan Lake Fishing Guides
The Six Lakes We Cover
Biwa, Kasumigaura, Saroma, Ogawara, Inawashiro, and Suwa — what's actually swimming in each one, and how to get on the water.
Fishing in Japan as a Visitor
Whether you need a license, the easiest trips with no gear, day trips from Tokyo and Kyoto, and the rules most visitors miss.
When to Fish Japan's Lakes, Month by Month
Trophy bass in spring, salmon in autumn, dome boats and ice fishing in winter: what's in season on each lake.
Fishing Lake Biwa, Basin by Basin
The shallow south basin, the deep north basin, bass and Biwa trout seasons, and the no-release rule that surprises most visitors.
Lake Kasumigaura, Tokyo's Tough Bass Lake
Reeds, riprap and sluice gates an hour from Tokyo, the best seasons, and why the release rules aren't the same as Biwa's.
Lake Suwa and Its Heated Dome Boats
Winter wakasagi from a heated boat on a lake that no longer freezes: season, prices, the permit, and the lure ban.
Lake Saroma, Where the Lake Is Really the Sea
Flounder, salmon and smelt on Hokkaido's seawater lagoon, the ports people fish from, and the shellfish rule you must not break.
Lake Ogawara, Aomori's Treasure Lake
Wakasagi ice fishing at Anenuma, summer shijimi gathering, cheap permits, and what to check before you go.
Lake Inawashiro, the Clear Lake That Changed
Record smallmouth bass and big trout in a lake that used to be too acidic for them, plus permits, seasons, and the night-fishing ban.
How Moon Phase Affects Your Bite Window
Major and minor periods explained — what the theory actually claims, and how much weight it deserves.
Rules Change From Lake to Lake
No-release bass rules on Biwa, cooperative-managed waters on Saroma, licensed boats on Suwa — what actually applies to each lake.
Lake Fishing Manners & Japanese Phrases
Bank spacing, keep-or-release norms, and the handful of phrases that help at a boat rental counter or tackle shop.
The Lures People Actually Use Here
Two of these six lakes are genuinely lure country. The other four run mostly on bait — and one bans lures outright.
TsureruKana: Will It Bite Today?
Our Android app for these lakes: a daily score, feeding windows, tide tables, lure picks and a catch log, plus what it can't tell you.
Everything You Need to Know About These Six Lakes
These six lakes were picked for how different they are, not just how big. Here's what's actually true about each one.
1. The Six Lakes at a Glance
- Lake Biwa (Shiga): Japan's largest lake at 670 km², about 20 minutes from Kyoto Station. World-renowned for largemouth bass that have rivaled the all-tackle world record, plus native ayu and funa.
- Lake Kasumigaura (Ibaraki): Japan's 2nd largest (220 km²), about an hour from Tokyo. Once a brackish bay, now freshwater after floodgates were built — a convenient bass lake, also known for wakasagi and catfish.
- Lake Saroma (Hokkaido): Japan's 3rd largest (152 km²), but a coastal lagoon, not a freshwater lake — two channels connect it straight to the Sea of Okhotsk, so it's nearly as salty as the ocean. Known for scallop and oyster farming; anglers fish for salmon, herring, and flatfish, not bass.
- Lake Ogawara (Aomori): The largest lake in Aomori, though only 11th largest nationally (63 km²). Also brackish, connected to the Pacific by the Takase River. Locally called the "Treasure Lake" for its shijimi clams, icefish, and winter wakasagi.
- Lake Inawashiro (Fukushima): Japan's 4th largest (103 km²) and one of its clearest. Once strongly acidic, its water has turned close to neutral since the 1990s, and it's now known for big smallmouth bass (a 2025 Japan record) and large trout.
- Lake Suwa (Nagano): Much smaller than the rest (13 km²), but one of Japan's best-known winter fishing spots — heated "dome boats" go out for wakasagi from autumn through winter, on a lake famous for its Omiwatari ice-ridge phenomenon.
2. Reading the Moon Before You Go
Solunar theory — the idea that fish feed hardest during two daily major periods (roughly two hours, centered on the moon passing overhead or underfoot) and two shorter minor periods (around moonrise and moonset) — has been a fixture of angling advice since the 1930s. It's on solid ground for tidal water: the moon drives real tides on Saroma and Ogawara, and a moving tide is a genuine reason fish feed harder. For the freshwater lakes on this list, there's no actual tide for the moon to create, and controlled studies haven't found a consistent effect once weather, light levels, and barometric pressure are accounted for.
That doesn't make it useless — it's a heuristic anglers have leaned on for generations, and a major period that happens to land at dawn or dusk is still a good window to be on the water for. Worth checking before you go, alongside the weather. Not a reason to skip a day the tables call "poor." (There's a note on the app we built for tracking this at the bottom of this page, if you'd rather not work it out by hand.)
3. Rules Change From Lake to Lake
- Biwa & Kasumigaura: largemouth bass are a designated invasive species in Japan, so moving them alive is illegal, and on Biwa releasing them is banned too — no license is needed to fish from shore.
- Saroma & Ogawara: much of each lake is working water, managed by local fishery cooperatives for scallops, oysters, and salmon. Stick to public bank access and posted recreational areas.
- Suwa: wakasagi fishing normally happens through a licensed dome-boat operator, not independent bank fishing.
- Inawashiro: a permit from the local cooperative is required, and night fishing is banned.
4. Boat Rental & Local Access
Marinas around Biwa and Kasumigaura rent bass boats by the half or full day. Ogawara has lakeside rental facilities for its own fishing. Suwa's dome-boat trips include rod, bait, and a heated seat as part of the price. Saroma is more locally guided — a fishery cooperative office or lakeside shop is the fastest way to find out what's allowed and what's biting.
Pro tip: check the moon phase alongside the weather, not instead of it. A major period during a stable, overcast morning usually beats a major period in bright midday sun.
Made by us
TsureruKana
We also build an app that scores major and minor feeding windows for each of these six lakes using solunar theory — worth checking alongside the weather, not a guarantee — plus a lure-matching suggestion for what's likely working right now.
iPhone version coming soon · See everything the app does