The old rule of hybridization everyone learns in school is two animals of the same species produce fertile offspring, two species of the same genus produce infertile offspring, and two species of different genera cannot produce offspring. This justifies brook trout and lake trout (two species of the genus Salvelinus) producing infertile offspring (splake). If the rule held fast 100% of the time, tiger trout wouldn't exist, since brookies and browns are of different genera - Salvelinus (char) and Salmo (Atlantic trout/salmon), but on rare occasion freaky things happen. So it's really more a biological barrier to more tiger trout existing than a behavioural or ecological one, and it would probably not be possible to reliably create this freak occurrance in a hatchery.
Anyway I agree with the others that the pic is a brookie.
