live foods imo/ime are the best foods for young spiney eels in general. blackworms for the smallest fish, then chopped up nightcrawlers, moveing up to full sized ones. why? they are finicky fish and will starve to death before takeing prepared foods unless you get lucky. once most large species are 12"+ or 6 monthes in captivity. they take frozen foods readily. once larger i offer live foods, and frozen foods. the trick is keeping the fish in good health but still hungry, and offering new foods consistantly. hand feeding makes transitioning even easier, they dont have teeth but are similar to boney tounge species as they can pack a " pinch" even my largest eels have never broken skin with a well aimed nip. but that was because i wasnt feeding fast enough lol.
bloodworms are like feeding a kid potato chips... they will keep them alive but youll see very slow growth. a majority of spiney eels and particularly fire eels never take to pellets or prepared foods. but can be transitioned onto frozen foods, and fresh seafood.