I personally love exotic eels, I have some of them and would love a collection
The eels i have:
Gymnothorax pseudothyrsoideus
Gymnothorax thyrsoideus
Gymnothorax favagineus
Gymnothorax punctatus
Echidna delicatula
Zibramuraena
Absolutely amazing eels, if you like suggestions and would like just one eel taking the spotlight it would definitely be the tessalata, i would say 210g is the minimum with lots of yellow tail damsels to add some activity
Personally, you can keep a Tess in a 180, that's only till they get to about 4 feet, that's when you need atleast a 300 gallon tank, for compatibility, no fish, unless it's small and fast as yellow tail damsels even then there's no guarantee
As for the gymnothorax fimbriatus, it's one of the most aggressive eels I've seen besides the tessalata, I've seen people keep the fimbriatus with the tessalata but the risk is high aswell as the budget of a tank size Lol
I would love the gymnothorax afer, but I can't order a specific species, i can only get what is in stock Lol