A fish weir is essentially a fixed barrier or trap built into a river to channel fish towards a catching point, and this one has a particular detail attached to it that is difficult to forget. Writing in 1889, the antiquarian T.J. Westropp noted a local tradition about a detached building near the river, possibly a mill, where the country people said that a rope from a net in the water rang a bell inside whenever a salmon was caught. Whether the building or the bell-rope survived into Westropp's own time is unclear, but the 1840 Ordnance Survey six-inch map still marks a small island in the river at this point, and on that island it records the ruins of a structure described as a Watch House, associated with the eel weir.

The wider context is Cistercian. The monastery of Monasteranenagh, a Cistercian foundation, lies about 145 metres to the south-southeast, and the weirs here were part of its economic holdings for centuries. The Cistercians, a monastic order known across medieval Europe for efficient land and water management, depended heavily on fisheries as a source of income and food. When the abbey was suppressed in 1540, a survey recorded by Power in 1930 found it in possession of sixteen townlands, a mill, a watercourse, and eel and pike weirs in the Camoge. The second eel weir, just 50 metres downstream to the west, suggests the monks were working this short stretch of river with some intensity. The Camoge also marks the boundary between the townlands of Monaster North and Monaster South at this point, a boundary that may itself reflect older monastic land divisions.

The stone structure of the weir is still visible in the river to the east of Monaster Bridge, though drainage works carried out in 1978 disturbed the riverbed at this location. The site sits in low-lying pasture, 100 metres upriver from the bridge, and the approach is quiet and unassuming. Visitors with an eye for stonework in shallow water, particularly at lower river levels, are most likely to make out the weir's remains. The ruined abbey to the south offers the clearest orientation point, and the proximity of the two sites to each other gives a sense of how tightly the monastery once organised the landscape around it.