jnapier,

Ditto to what M.Paris says. He's correct sticklebacks are consumed by trout in some habitats although I do not know which species. A forage species that the trout will eat and does not get too large for forage would be a plus in my opinion.

You may want to consider triploid trout that won't produce eggs or engage in spawning activity. That is if they are available.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.