I think if you put 2 eels and a fuzzy dwarf in your 55 you may be overstocked or close. Our LFS
says not to put 2 different types of eels together. I'm not positive thou. Someone with more experience in that area will chime in
I personally would recommend 2 fuzzy dwarfs and one of the eels. We will be adding a Humu trigger to our 75 but they need a minimum of 70 gallons. Good luck!