I have 12 black widow tetras. The largest is about an inch and a half long. I also have about 15 ghost shrimp running around cleaning for me. This morning I noticed the largest tetra had eaten one of the shrimp. He still has the antenna of the shrimp sticking out of his mouth, is this going to cause him issues or will he digest it eventually. His belly is obviously full. Thanks.
Freshwater crustaceans (like shrimp) are a typical natural food for most tropicals such as characins (tetra are characins), so if it will fit in their mouth... expect the rest to follow. The fish will manage to digest it.