Thanks for the insight, Ducksta.
The waters in the photo look more turbid than what the videos tend to show in Sth America. Maybe exposure to turbidity causes colour washout.
If you look at the GE shot you'll see that the area is cultivated with small cane holdings. Hundreds of them.
But even so, you're right about the aquarium suppliers having a short list of people with aquarium set-ups of the kind necessary to be keeping these.
So, information and suspicion aplenty but not necessarily proof yet.
Interesting trying to identify what type is in the photo though.
Are these fish declared noxious under Qld's Bio-Security Act?
No, I don't think so. Emperor or Giant Cichlids certainly are but I think they're a different version from Africa.
Maybe at worst legally, the offender/s breach some Fisheries reg or other about releasing non-native fish into the environment.