Need expert's help with my friend's flowerhorn.

[Baloch]

Guys this flowerhorn is not so active and looks hideous. Few weeks ago he was very active and healthy, I don't know what actually happened to him but my friend asked for help since he doen't know much about flowerhorns. This flowerhorn was in a 90 g with an arowanna. This is how he used to look:

 

[convict360]

What tank size is he in now? If we're talking less than 75 gallons, water quality would be highly suspect if he isn't getting regular large changes. That's just speculation though, need more to go on.

Tank size, water parameters, physical indications such as faeces colour etc will help

 

[Ihsnshaik]

We need the full story here. What happened leading to his inactive state. How's water quality? Anything new added? Any lesions? Stringy poo? His color changed to a darker red. Is arowana stressing him? We need to know a hell a lot more than he's just hideous and he looks the same to me but more red

 

[Bpera002]

Also about how old is he?