Arctic Char (Salvelinus alpinus)
Current record: 9lb 8oz
Water: Loch Arkaig, Inverness
Arctic charr (Salvelinus alpinus) is a cold-water salmonid found in a small number of deep, clean lakes across Scotland, the Lake District, and Wales, some of the last surviving native populations left over from the last ice age, cut off in isolated lakes as the glaciers retreated.
Closely related to both lake trout and salmon, Arctic charr shows striking colour variation between populations and through the year: a dark back with flanks and belly ranging from white through yellow to a deep spawning red, the exact shade depends heavily on the specific lake and the season.
Diet shifts with the seasons too. Through late spring and summer, charr take insects off the surface, salmon eggs, snails, small crustaceans, and fish up to a third of their own size. Come autumn and winter, they switch to zooplankton and freshwater shrimp, picking up the odd small fish along the way, more than 30 different prey species have turned up in stomach content studies, about as opportunistic a feeder as you'll find.
Because they need cold, oxygen-rich, unpolluted water year-round, Arctic charr are a genuinely reliable indicator species, if a lake still holds a healthy charr population, that's a strong sign the water quality is in good shape.