It's staying up top to steer clear from tankmates in my opinion. If there was a small EB group, It'd be a little more active and stick together. The EB Acara looks healthy to me and the sunken belly can occur on fry since they're tank raised.
The sex of this fish is uncertain. I've had many spawning pairs, and still can't tell if its a male or female. They both show their breeding dress, had females larger than males and vice versa. Females can get long dorsal and anal fins too. Only way I'm able to visually see the difference is the when the female drops her tube. Just my thoughts here. Good luck nonetheless.
The sex of this fish is uncertain. I've had many spawning pairs, and still can't tell if its a male or female. They both show their breeding dress, had females larger than males and vice versa. Females can get long dorsal and anal fins too. Only way I'm able to visually see the difference is the when the female drops her tube. Just my thoughts here. Good luck nonetheless.