Think u are right on the taste. fish dun fancy these worms. i read abit about these worms and found a discussion thread and the fishes that eat the worms.
I have no idea what fishes are they talking about except for some.So Far fish that do eat planaria:
Ciclids (angel fish do eat planaria)
This is the site :
Maybe for u would be best for u to use ur method since it is a shrimp tank and fishes might harm ur shrimps. Planaria worms are harmless as explained in various sites but the fact that they appear means to much of leftovers, dead fish....
More on the worms here: