Rainbow Trout fishing in Lake Ashi

Easily combined with a Hakone onsen stay.

March, April and October are the prime months. A cooperative day permit is required.

When

Season grading is our editorial judgement, not a sourced figure. It says when the fish is catchable, not when the water is legally open — for that, read the closed seasons below.

Do you need a permit?

A cooperative day permit is required. Typically ¥1,000–2,000.

Water: Freshwater
Prefecture: Kanagawa
Region: Kanto
Getting there: 90 min from Shinjuku, in Hakone

How far our answer goes here

✓National lawApplies everywhere. Foreign-national gear limits, protected species, bluefin controls.
✓PrefectureMinimum sizes, closed seasons and legal gear. This is a floor — local rules add to it, never subtract.
~Sea-area / inland committeeDirectives that close specific waters or periods. We hold these for a few prefectures only.
✓Cooperative permitAshinoko Fishery Cooperative 芦之湖漁業協同組合
Holds the Class 5 common fishery right for Lake Ashi. Its permit rules were revised on 1 January 2024. Note that Kanagawa's yamame and iwana closed seasons explicitly exempt Lake Ashi.

Rules stack. Everything above the line we hold; everything below it you still need to confirm on the ground. That gap is exactly what a local guide is for.

Size limits and closed seasons

Kanagawa 神奈川県 VERIFIED

Set by the Kanagawa Fisheries Adjustment Rules. Taking abalone, sea cucumber or glass eel carries up to 3 years or ¥30,000,000.

Applies to: Sea and inland. The source regulation covers both sea and inland waters. Cooperatives add further rules on rivers and lakes.

Closed seasons

Ayu (sweetfish)アユ	1 Jan – 31 May, and 15 Oct – 30 Nov	On parts of the Sagami and Sakawa the autumn window starts 1 Nov instead.
Yamameヤマメ	15 Oct – end of Feb	Lake Ashi is exempt.
Iwana charイワナ	15 Oct – end of Feb	Lake Ashi is exempt.
Sculpinカジカ	1 Jan – 31 Mar
Pond smelt — Lake Tsukui and Doshi Riverワカサギ（津久井湖・道志川）	1 Mar – 15 Apr	Committee instruction.

May not be taken at or under this size

Rainbow troutニジマス	12 cm total length or under
Yamameヤマメ	12 cm total length or under
Iwana charイワナ	12 cm total length or under
Common carpコイ	18 cm total length or under
Japanese eelウナギ	24 cm total length or under

Prohibited methods

Inland — Weir traps, set nets and sweep nets
Inland — Any gear with a launching mechanism
Inland — Cast net between one hour after sunset and one hour before sunrise
Inland — Bin traps, dewatering, electric current, and any method using light
Inland — **Diving goggles** — using a mask to spot fish is prohibited (a viewing box is allowed)
Inland — Taking salmon anywhere in inland waters (Fisheries Resource Protection Act art. 28)
12 named weirs and intakes — Taking anything within the posted distances above and below the structure — on the Tama, Sagami and Sakawa

Kanagawa bans the use of **diving goggles** to find fish in fresh water, which catches out visitors who assume snorkelling and spotting is harmless. Twelve weirs and intakes on the Tama, Sagami and Sakawa have no-take zones measured in metres above and below the structure. Six cooperatives hold the fishery rights; each sets its own permit rules, and several were revised in 2025–26.

Local committee instructions

Smallmouth bass and similar: taking them out alive, and returning them to the water, are both prohibited year round.
Carp: taking them out and stocking them are restricted year round.
Corbicula in the Tama River: taking, possessing and exercising the common fishery right are all restricted year round.
Lake Tsukui and the Doshi River: cast netting is prohibited in defined zones year round; pond smelt is closed 1 Mar – 15 Apr.

The prefecture publishes a Q&A on recreational fishing rules (PDF).

Source: Kanagawa Prefecture, Fisheries Division — river and lake rules (updated 27 Jul 2026) and sea rules (16 Jul 2026). Kanagawa Fisheries Adjustment Rules arts. 34, 35, 37, 38. https://www.pref.kanagawa.jp/docs/kb2/cnt/f790/p504690.html✓ checked 2026-08-28

About Rainbow Trout

Widely stocked in lakes and managed river sections.

Japanese: ニジマス · nijimasu
Scientific name: Oncorhynchus mykiss
Typical size: 25–60 cm (10–24 in)

How it is fished here

Fly fishing, Lure casting