We caught the baricuda in one of our live feeder outings with a minnow siene (he was 1" long, and has grown to about 7" in 11 weeks, so no, the 300 is way too small, as they can reach 6'....ours will be returned to the sea in a few weeks, as soon as the water temp is appropriate)
There is an alternative if you can find one though, as 'cudas have a look-alike little brother called a southern sennet which averages 8"-10".
Surprisingly, the 'cuda is great in the tank, hanging to the top and staying away from the other fish and bothering none of his tank mates and approaching the glass and waiting for food just like the rest (lionfish, lunare & dragon wrass, etc.)
Curiously, baricudas eat their prey tail-first, and in instances where the foodfish is too large, will bite them in half and then swallow both halves tail first (we've raised over a dozen over the years).....we like to joke that he just proving how tough he is and LIKES the spines sticking in his throat!!**grin**
There IS an inherent risk involved though, as even at 7" he's capable of slicing a finger to the bone, and each inch makes the severity more likely....I ALWAYS feed him before working with my hands in the tank.