Well, lights came on this morning and my 8" arowana had vanished. There are no gaps for it to escape but had a look anyway, then I noticed my 11-12" bass had a big belly.. Lesson learned, bass will give anything a go.
The only thing I had in with my bass that it didn't try to eat was a venustus. Seriously half the size and twice as aggressive as the bass, almost killed her. Sorry about your loss