Lough Mask is one of Ireland's great wild brown trout lakes — a vast limestone system that stretches between County Mayo and County Galway, defined by its clarity, scale, and the quality of the fish it produces. At roughly 20,000 acres, it is one of the largest trout waters in Ireland, yet it rewards intimacy: the angler who learns its bays, reefs, and island margins will find fishing of the highest order.
The lake sits on a deep limestone bedrock that gives the water its characteristic clarity and alkalinity. Extensive shallows, submerged reefs, rocky islands, and marl flats create a mosaic of habitat that supports exceptional insect life — olives, buzzers, sedges, and, most famously, the mayfly. The shoreline shifts from open exposed limestone shelves in the west to quieter bays and sheltered coves along the northern and eastern margins.
Lough Mask is celebrated above all for its wild brown trout. These are hard-fighting, well-conditioned fish with the amber flanks and strong backs of limestone lake trout at their finest. A good fish runs to 1.5–2.5lb, but fish of 4lb and above are taken each season, and the lake's ferox population — predatory trout that inhabit the deep water around islands and reefs — can exceed 20lb in exceptional cases.
The mayfly period from mid-May into June is the defining event of the Mask season. When conditions align — steady south-west wind, overcast skies, water temperature in the right range — trout move up from depth onto the limestone shelves and feed with abandon on emerging duns and spent spinners. It is among the most celebrated dry fly spectacles in Irish angling. The lake does not switch off after the mayfly: August and September bring equally memorable fishing as large trout patrol island margins and shorelines in search of dapping flies and terrestrials.
Fishing Mask is boat fishing. The lake's extensive reefs, variable water levels, and often considerable swell make shore fishing a secondary option. Most anglers drift with the wind across productive shallows using a drogue to control speed, working three or four flies across the surface. A local boatman or experienced companion is strongly advised for first-time visitors: the lake's hidden rock systems and sudden weather changes demand respect.
The main angling base is Ballinrobe, with additional access points at Cushlough, Tourmakeady, Ferry Bridge, and Cong. Boat hire is available from several local operators. Lough Mask is not an easy water — it rewards preparation, local knowledge, and patience — but for the angler willing to put in the effort, it offers a quality of wild trout fishing that few waters in Europe can match.
Access & bases
The main angling base is Ballinrobe in Co. Mayo, which has tackle shops, accommodation, and boat hire services. Additional access points with slipways and moorings are at Cushlough (eastern shore), Tourmakeady (western shore), Ferry Bridge (upper lake), and Cong to the south. A boat is strongly advised — the lake's extensive reefs, submerged rock systems, and variable water levels make shore fishing limited in productivity and navigation hazardous without local knowledge. Experienced boatmen are available locally. Life jackets are essential: Lough Mask can produce sudden wind shifts and significant swell on its large open fetch.
The Mayfly Hatch
The Lough Mask mayfly hatch is one of Ireland's great angling spectacles. Large, creamy mayfly duns emerge over shallow limestone areas as water temperatures reach the right range, typically from mid-May into June. Spinner falls on calm evenings can produce exceptional surface activity. Trout move into 2–6 feet over marl and broken rock, feeding with unusual confidence. Positioning the boat over a productive drift where fish are rising steadily — rather than chasing individual fish — is the key to success.
Late-Summer Dapping
Mask is renowned for its August and September dapping fishing. On calm, humid evenings, large trout patrol shorelines and island margins, looking up for grasshoppers and terrestrials that fall onto the surface. Natural dapping with live grasshoppers is the traditional method; artificial dapping patterns produce consistently when natural insects are not available. Some of the heaviest fish of the season are taken in this late window.
Limestone Ecology
As a limestone lough, Mask supports exceptional insect life year-round — strong olive hatches, abundant chironomid populations, sedge activity in warmer periods, and of course the mayfly. The clear, fertile water produces fast-growing, hard-fighting trout. This richness of food source means fish are in excellent condition throughout the season, not just during the headline hatches.
Ferox Trout
The deep-water ferox population is part of Mask's mythology. These predatory trout, which can historically exceed 20lb, inhabit the deep water around islands and reefs. Deep trolling in 10–30 feet with hardware or large streamers is the primary method. While not a fly fishing quarry, the possibility of encountering a ferox adds a distinct character to the lake that few Irish waters share.
February – April
The early season begins quietly. Fish hold deeper and subsurface techniques dominate — slow wet fly drifts over deeper drop-offs, buzzer fishing in sheltered bays, and early olive patterns as April progresses. Evening rises increase late in the month. Wind direction becomes critical to success, with south-west winds offering the most productive conditions.
Mid-May – June
The mayfly period is the defining event of the Lough Mask calendar. Timing varies with temperature and weather, typically from mid-May into June. Trout move from depth onto limestone shelves and feed confidently on emerging duns and spent spinners. Experienced anglers position boats over productive drifts where fish rise steadily. Drift control and fly presentation are everything.
July
Fishing can slow in high pressure and bright conditions. Early morning and late evening sessions produce best results. Sedge patterns come into play in the evening. Wind remains essential — a dead calm July day on Mask is a difficult one. Terrestrial patterns near the shore offer sport when hatch activity is limited.
August – September
Late-season fishing on Mask is special in its own right. Large trout patrol island margins and shorelines in search of dapping flies and terrestrials. Natural dapping with grasshoppers is the traditional approach; artificial dapping flies produce consistently when natural supply is short. Larger wet patterns and claret-based flies work well as fish switch feeding mode. Night buzzer fishing can revive sport in warm spells.
Cushlough Bay
A sheltered bay on the eastern shore, productive early in the season for buzzer fishing. Good access with a slipway. A reliable starting point for anglers new to the lake.
Carrigeenavall & Castle Hag Areas
Extensive shallow limestone shelves that produce excellent mayfly and sedge fishing. Among the most productive zones on the lake during the hatch period.
Ram's Horn Bay
Excellent drifts with particularly productive August–September dapping conditions. The sheltered margins and island edges draw large trout in late season.
Rocky Shore (Lively Bay to Ballygarry)
A large, shallow limestone expanse on the eastern shore. Ideal for mayfly and wet fly fishing, with extensive drifts available in south-west and west winds.
Inishowen & Canal Area
Noted for producing larger-than-average trout. Strong sedge and olive fishing, with the canal connection to Lough Corrib adding historical character to this corner of the lake.
Ferry Bridge (Upper Mask)
The upper section of the lake has a distinct character from the main body — quieter, with productive duckfly and sedge fishing. A worthwhile area to explore mid-season.
🎣 One-Day Visit
Hire a boat and experienced boatman and focus on one productive zone — Cushlough in early season, the mayfly shallows in May–June, or the island margins in August. A focused single-day approach yields far more than trying to cover the whole lake.
🎣 Three-Day Focused Trip
Rotate between the mayfly shallows, island drifts, and dapping zones to experience the range of the lake. Three days gives enough time to adapt to conditions and refine approach based on what the lake is doing.
🎣 Five-Day Premium Trip
Combine Lough Mask mayfly fishing with a session on Lough Corrib via Cong, and add a guided ferox trolling day for anglers who want to target the deep-water leviathans. This is one of the great Irish angling weeks.
