I'm confused. You have no interest in getting an Eel but want to know what size tank for two? Did I read that right? It totally depends on what type of Eels they are. I would say 100g minimum in general for two (Snowflake and Zebra Moray for example). You could probably do a 75 but that is pretty cramped so bigger is always better. Anyway, hope this helps and good luck.