from The Century Dictionary and Cyclopedia
- n. A local name of a variety of the common trout (Salmo fario stomachicus) of certain parts of Ireland (Galway, etc.), in which the coats of the stomach become thick, like the gizzards of birds, from feeding on shell-fish. Also called gizzard-trout.
Sorry, no etymologies found.
Another classification problem concerns the brown trout of Lough Melvin, Ireland, where three distinct populations—a large predatory trout known as “ferox,” a moderate-size invertebrate feeder known as “sonaghen,” and a smaller trout specializing on benthic food, snails, and crustaceans, known as “gillaroo”—coexist and maintain their identity.
Now, however, science admits but one species, though, to such well-defined varieties as the Loch Leven trout, the estuarine trout and the gillaroo, it concedes the right to separate names and "races."
Feeding on shell-fish thickens the stomach, and in many generations, probably, the gillaroo trout becomes so distinct a variety, as to render it doubtful if it be not a distinct species.
On the hills behind the inn there is a small loch, called the MULACH-CORRIE, in which it is said that the gillaroo trout are to be found.
It would gladden the heart of Izaak Walton, as it is full of fish, among which is the famous gillaroo trout, which will not rise to the tantalising fly.