Mealworms are ok, but not great. They are very high in fat and although some sources say they are a good source of protein, the types of protein they have are not really the ones that your fish needs most. Protein is the measurement of amino acids that can be digested by the fish. The amino acid contents of mealworms are not particularly good for a piscivorous fish like an endlicheri. You can include them in the diet but I would also feed other things as well. Earthworms were just what I used to get my baby endlicheris to eat, but I haven't looked into their amino acid composition.
