I keep a Barred Eel with a Snowflake Eel. They have been together for many years. The Barred Eel has recently scoffed at all of her food offerings. Things she normally eats. I do three options. My own mix of frozen, krill or silversides. The Snowflake will sometimes eat every day. The Barred Eel has always eaten much less than the Snowflake but has refused food longer this time than usual. Its a 120g with a Grouper. It has a 120g sump with lots of filtration. The Eels are not fighting as far as I can tell and they never have.