Leonard voiced my exact sentiments. When it was said that they are mainly scavengers, it is more that they are opportunistic feeders. They will not pass by a free and easy meal of a dead or dying fish or crustacean or mollusk, but that does not mean they don't hunt. As was said, they often hunt at night, when other fish are sleeping, and make easy prey. That is why I would not trust an eel with small fish like firefish. During the day, the firefish may dart into the eels layer, and the eel may not do anything, but at night when they are sleeping, your eel will probably swim over and slurp them down. Also, as far as the zebra, it has already been said, but it bears repeating. Despite what they are inclined to eat, they won't pass up an easy meal, so if the opportunity presents itself, your fish could disappear. Snowflakes, by the way, are one of the less aggressive eels out there, and the zebras are just plain fat and lazy.