Fishing by the moon is older than the fishing rod. Thai fishermen have understood for generations that certain phases of the lunar cycle produce better catches than others — not through mysticism but through direct observation across thousands of days on the water. Modern solunar theory provides a framework for understanding and predicting these patterns, and the combination of empirical fishing records from Thai venues with solunar calculations gives a practical planning tool that experienced anglers use alongside weather forecasts and tide tables.
Solunar Theory: The Mechanism
Solunar theory, developed by American naturalist John Alden Knight in the 1930s, proposes that fish feeding activity peaks during periods of strong gravitational influence from the moon and sun — specifically when the moon is directly overhead or underfoot (major periods) and when the moon is at 90 degrees to the earth-angler axis (minor periods). Each 24-hour period contains two major periods and two minor periods of approximately one hour each.
The gravitational influence operates independently of tidal height — it affects barometric pressure, the behaviour of zooplankton (which drives baitfish movement, which drives predator feeding), and possibly direct hormonal or physiological responses in fish biology. In Thai waters, the correlation between solunar major periods and observed fishing peaks is supported by anecdotal logbooks from Phuket charter captains tracking GT activity and by the records kept by experienced guides at venues like Bungsamran and Gillhams.
Using a Solunar Table
Solunar tables are published monthly in printed fishing magazines and available through apps including Fishing & Hunting Solunar Tables, Sportsman's Guide Solunar, and the Navionics companion apps. The table provides daily major and minor period times adjusted for the user's location. For Thailand (UTC+7), most solunar apps require only a location input to compute locally adjusted times.
The practical application: identify the two major period windows for the day (each lasting approximately one to one and a half hours) and ensure your most productive bait or lure is in the water during those windows. Minor periods are worth a brief change of technique or location. Outside these windows, reduce fishing intensity if session length is limited.
Solunar tables are most reliable when they coincide with tidal movement. A major solunar period that falls at the peak of a spring tidal run in the Andaman — both moon-related phenomena aligned — produces what experienced charter captains describe as an "event window": a concentrated feeding frenzy that may last only thirty to forty-five minutes but that is extraordinarily productive.
Giant Trevally and the New Moon
Giant trevally (Caranx ignobilis) are arguably the most moon-sensitive species in Thai saltwater fishing. Their feeding behaviour at different lunar phases is distinct enough that experienced Andaman GT guides adjust their tactics significantly between new moon and full moon sessions.
New Moon GT Behaviour
On new moon nights the sky is completely dark. Baitfish that rely on visual predator detection are effectively blind to surface threats. They congregate around any available light source — floating debris, the bioluminescent surface of shallow reef areas, jetty lights visible from offshore. GT exploit this, positioning themselves at the edges of these light concentrations and ambushing disoriented baitfish with unusual aggression.
For daytime fishing, new moon periods in the Andaman — at Koh Rok, Hin Daeng and Hin Muang, and the outer islands of the Tarutao group — produce fast, aggressive surface GT strikes. The fish appear to feed throughout the day rather than in distinct dawn and dusk windows, possibly because the lunar night feeding activity displaces their standard tidal feeding rhythm.
Popping and stickbait fishing at Hin Daeng and Hin Muang during new moon spring tides is the most consistently productive GT combination in Thai waters. Charter boats out of Koh Lanta targeting these locations specifically book for new moon + spring tide combinations.
Full Moon GT Behaviour
Full moon periods produce good GT fishing through different mechanisms. The bright moonlit nights allow visual feeding through the darkness hours, which means GT at tidal point locations feed intensively through the night and may be less active during the day as a result. Dawn fishing in the hour after sunrise on a full moon day often catches GT that are completing a long night feed rather than beginning a fresh day feeding period.
Full moon periods are also associated with increased GT activity at surface structure in deeper water — around floating debris, FAD systems, and the surface thermocline edges that are more defined during the neap/full moon period. Trolling and stickbait fishing at these locations produces different-size class fish compared to reef-based popping: the full moon fish tend to be larger, pelagic-feeding GT rather than the medium-sized reef-associated fish that dominate new moon popping sessions.
GT Moon Records
Charter operators based in Koh Lanta who maintain fishing logbooks report that their largest individual GT caught on popping tackle (above 30 kg) are disproportionately distributed around new and full moon dates with spring tidal conditions. While sample sizes are too small for statistical significance, the pattern is consistent enough to inform trip planning.
Mahseer and the Full Moon in Northern Rivers
The mahseer — specifically the Siamese giant carp (Tor tambroides) and the hump-backed mahseer found in the river systems of northern and western Thailand — display a seasonal lunar feeding pattern that differs significantly from the saltwater GT pattern.
Full Moon Aggression in Thai Rivers
In the Mae Klong River system (Khwae Noi and Khwae Yai tributaries near Kanchanaburi), the Pong River system in the North (accessing the upper Khong/Mekong drainage), and the smaller rocky rivers of Doi Inthanon and Doi Suthep drainage areas near Chiang Mai, mahseer feeding intensity increases markedly during the full moon phase.
Anglers fishing the Khwae Noi with surface poppers and large spinnerbaits during the three days before and after full moon report significantly higher strike rates than during the same conditions at new moon. The fish appear to be triggered by the brighter nocturnal light environment, which extends their active feeding window and increases their aggression toward large prey items.
The mechanism in freshwater for mahseer is likely related to prey behaviour rather than tidal gravitation. The full moon illuminates river pools sufficiently for mahseer to hunt visually through the night. In the dark, shallow rocky rivers of the mahseer's Thai habitat, the additional night-time light from the full moon extends the productive feeding window from the standard dawn/dusk periods into the night, resulting in fish that are more fed — and paradoxically, in the experience of guided fishing, more aggressive toward lures during the following day's session as their natural prey items are also more active.
Mae Klong Full Moon Sessions
The rivers feeding the Mae Klong near Kanchanaburi — particularly the Khwae Yai above the Srinakarin Dam reservoir — are the most accessible mahseer venues for Bangkok-based anglers. A two-day trip timed for the full moon phase in the dry season (November to April, when river levels are stable and clear) is the standard approach for targeting mahseer above 10 kg at these venues.
Freshwater Stingray Sensitivity
Giant freshwater stingray (Urogymnus polylepis) in the Mae Klong, Mekong tributaries in northeastern Thailand, and the Chao Phraya tributary system below the dam network are among the most moon-sensitive freshwater species documented in Thai fishing records.
New Moon Stingray Activity
Freshwater stingray are predominantly nocturnal feeders, locating prey by electroreception as much as by smell. On new moon nights the absence of light does not disadvantage them — they locate buried shrimp, small fish, and crustaceans by electrical field detection regardless of light levels. During new moon periods, feeding activity throughout the night is intense, and the daytime feeding period extends later into the morning hours than during full moon periods.
Guides at the Mae Klong stingray venues near Ban Pong report that their most frequent hookups occur in the three days around new moon, and that the morning session (06:00 to 10:00) is most productive in this lunar phase. Full moon stingray sessions produce fish but the concentration of activity in the dawn period is less pronounced — the fish appear to have fed through the night and are less active at first light.
Practical Moon Planning for Stingray
For anglers specifically targeting giant freshwater stingray at Mae Klong venues near Ban Pong (the most accessible and productive stingray fishery in Thailand), scheduling sessions for new moon phases substantially increases catch probability. The best combination is: new moon + warm overnight temperatures (March to May) + stable river level (not in flood). This combination produces the highest consistent hit rates reported in guide logbooks over multiple seasons.
The moon does not guarantee fish. It sets the stage. Tide, temperature, bait, and skill determine whether the scene produces. But when the stage is set by a spring new moon and your lure is in the right place at the right solunar hour, Thailand can produce fishing that is difficult to explain by any other factor.
Integrating Moon, Tide, and Season
The most productive Thai fishing sessions consistently occur at the intersection of multiple favourable conditions, not at the presence of any single factor.
Optimal Andaman GT session: New moon + spring tide + Andaman dry season (November to April) + northeast swell below 1.5 metres + wind below 15 knots. Sessions meeting all these criteria at Hin Daeng/Hin Muang are exceptional.
Optimal Gulf cobia session: Full moon + spring tide (producing strong current at the channel marks south of Koh Samui) + early season mackerel (January to March) + the major solunar period falling within the morning fishing window.
Optimal mahseer session: Full moon + dry season stable river level + clear water (below 0.5 Secchi depth turbidity) in the Khwae Noi above Kanchanaburi + morning solunar major period aligned with the dawn session.
Optimal freshwater stingray: New moon + warm night temperature + low, stable Mae Klong water level + minor solunar period at 06:00 to 08:00.
None of these conditions can be perfectly predicted or always scheduled — real fishing involves compromising the ideal and fishing the best available combination. But understanding the moon's role in these intersecting systems allows a Thai angler to make better decisions about when to book the guide, when to drive the four hours from Bangkok to Kanchanaburi, and when to trust the local knowledge that says "wait for next week's moon."
Solunar Major Periods in Thai Waters: Sample Data
The following major period windows illustrate how to apply solunar tables at a Bangkok-area pay lake versus an Andaman charter:
Bangkok pay lake (Bungsamran), May 2026:
- Full moon: approximately 07 May. Major periods 06:30–07:30 and 18:45–19:45.
- New moon: approximately 22 May. Major periods shift to approximately 12:10–13:10 and 00:20–01:20.
The new moon midday major period aligns poorly with comfortable pay-lake conditions (midday heat reduces fish surface feeding), while the full moon morning major period overlapping dawn is a prime window.
Andaman GT charter (Koh Lanta departure), May 2026:
- The southwest monsoon onset in May reduces Andaman GT fishing opportunities significantly. Plan new moon GT sessions for November through April when the Andaman is accessible and GT populations are at the outer islands.
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