Freshwater EEL

[Umbra]

Definitely not A. australis (or any shortfinned eel), take a look where the dorsal fin starts relative to the pectoral fins/head - definitely a species of longfin eel. A. reinhardtii is very infrequently offered for sale outside of Australia and Japan relative to A. marmorata, not to mention that marmorata naturally occurs in OP's country.

A. marmorata is almost certainly the most likely suspect!

 

[d3ssen27]

I will update with some new pictures soon.

 

[Andyroo]

I've had a few locally caught American eels - very smart, very active, very very good fun.
also very strong, very diggy & very destructive to the decorations... so it goes. Use bamboo segments & they'll be all over the place, which quickly gets to be Ok. Plants with roots, not so good.