You'd be better off feeding chopped earthworms. I've had fish hesitate on eating earthworms. I fixed that by mixing the chopped earthworms with some thawed O.N. bloodworms to get the BW scent on the earthworms.
Earthworm nutritional value:
The above is somewhat misleading, as there is a major difference in nutritional content of a fresh worm that mostly consists of water (a non nutrient), and the nutritional content of a food where the water portion has been removed. Such as freeze dried worms. See below.
"Approximate analysis of earthworms was completed by Dr. Carl Cater in the Oilseed Products Laboratory at Texas A&M. He reported that on the samples tested moisture (volatile) averaged 80.44%. A further analysis of freeze-dried earthworms indicated the following components: oil 6.8-7.1%, nitrogen 10.6 - 11.0%, protein 66.2 - 68.6% and ash 9.3 - 9.7%. This would indicate that on whole, live earthworms are less than 14% protein. Therefore its use as food or a feed supplement would probably be limited. It should be noted that the freeze-dried product (after water is removed) compares favorably with defatted soy flour from the standpoint of amino acid availability. Further research may lead to the use of earthworms as a food supplement but this use is at best only a potential market."