What's the temp? How often do you feed? Any bullying that you've noticed?
If the water is that cool, I'd only feed once a week (maybe less). The fish will have a bigger appetite with warmer seasons, and smaller appetite with colder seasons. Also, instead of blood worms, try live black worms. They're healthier for the fish and more appetizing. And uneaten food will not go bad; the live blackworm will live in the substrate.
Just a thought.
I get them at my LFS. They're not much bigger than blood worms and are perfect for small predators (I feed them to my 1" bichirs and 1" dats). Many people use them for fish that aren't eating.