Confidence: I'm as sure as I can be.
Notes: An alderfly larva taken from the stomach contents of a hill lough brown trout. 14mm long. Lateral gill filaments can be seen lying across the abdomen, the first 7 segments of the abdomen has a pair of gill filaments, one either side. IDed from 'Freshwater Life' (Greenhalgh and Ovenden 2007). Difficult to say which of the Sialis species.