Lough Cullin receives its water from lough Conn through a narrow cut at Pontoon and also from the Ballavary river and then empties into the river Moy at its eastern end through the Cross river. Cullin is a very shallow rocky lake being only 1-2meters deep all over. It has one of the earliest olive and mayfly hatches in Ireland because the shallow water warms up quickly in spring. It has a huge duckfly hatch in March followed by the olives and mayfly in April/early May. Cullin gets a good run of Spring Salmon and Grilse starting in January and continuing right through until September. There are many Salmon caught here every season by trout anglers using normal trout wetfly techniques, but there are some fly fishers who intentionally target the salmon in the lough with good results. Lough Cullin is similar to Carrowmore Lake in that it is shallow all over making it ideal for Salmon fly fishing.