To me it just looks like a juvenille
Epinephelus lanceolatus or bumblebee grouper as there called they can live in freshwater to start out life with but need more and more salinity as they age some ppl claim they can be 100 percent freshwater and may live for a few years but its not true.it could also be a hybrid of the above with a smaller grouper family member cant think of the name which are hybridised in captivity which are in freshwater which they claim has magically made a fw species but agen the age they live for in fw is unknown few years top.