← Field Guide
Brook Trout
James St. John; James St. John (47445767@N05) / EOL (CC BY) · CC-BY

Brook Trout

Salvelinus fontinalis

trout
  • The body is olive-green covered with pale yellow spots and distinctive red spots rimmed with blue halos — no other common trout has this exact combination.
  • The lower fins (pectoral, pelvic, and anal) are orange with a clean white leading edge followed by a black stripe — look for that white-then-black border as a quick field identifier.
  • The back and top of the head show a worm-like pattern of wavy markings called vermiculation — a maze of lighter squiggles on a dark olive background that no other trout shares.
  • The tail fin is more square and less forked than most other trout, which is why anglers have long called this fish the 'squaretail.'