starry night, african slender eel... i have 2 atm they get along great. my big ones abit over 12". and seems to have slowed down abit. so i dont tink they will get too much past this. he is still less then 1 yr old so i may be wrong. 75 should be large enough for him. mine love blackworms, i just add a good chunk to the tank once a week and the eels and clown loaches forage for them all week. they will eat guppy fry but otherwise they are one of the gentlest eels ive owned ( right behind fire eels)
as the name suggests they are from africa i keep mine in fairly hard water and they do great, just like any other eel they are sensitive to water perameters and are delicate in this manner.
once my guys settled in they are very outgoing, mine will come out for food without hesitation ect one of the more active eels ive owned as well.
imo they are one of the best smaller spineys to own.