These are freeze dried, but I forgot the name in English .
Normally we give them as a snack to the chicken but I thought maybe it can be used for the fish too?
Mealworms are not much more than chitin, which really isn't really healthy nor digestible, and it can actually build up in the stomach / gut. Use as a treat only once in a while. There's really no nutritional value when they are dried.
Actually, FD mealworms have a beneficial nutritional value with 53% protein, 28% fat, and 6% fiber. The remaining value is 5% moisture. As stated, they should be offered only occassionally due to their chitinous exoskeleton.