Good for using trout pellets as bait. The trout obviously recognized the pellet as food. As long as you remove all pellet caught trout you catch, you should not have problems with producing hook smart fish. Depending on the size of the stomach content bug that is partially digested, from the shape of the antenna, it looks like the underside of an aquatic isopod (aquatic sow bug - Asellus). If it is large maybe the underside of a crayfish? How wide were the flooring boards to estimate the size of the 'bug'.?
Here are the links to the articles about browns being the more difficult trout to catch in ponds. I especially like the bulletin from Washington State Extension; lots of good pond trout info in it. Thanks to Cecil Baird (CB1), he is my go-to pond trout raising expert.
In the New York publication see page 8 for trout info. https://ecommons.cornell.edu/bitstr...agement+In+New+York+Ponds.pdf?sequence=2https://research.libraries.wsu.edu/...0756_1981.pdf?sequence=1&isAllowed=y