I've had about 6 arapaimas in the past and they've all died. The pH was within range (6.5) and i did a 15-20% water change every week. Every time i bought an arapaima they were very aggressive eaters but they would have the tendency to hang out in the corner of the tank and not really swim around too much. Other than that I didn't notice any signs of disease related issues and yet they would die within a month or two of having them. Does anyone know what other requirements are needed for these fish and recommendations if possible?? your insight is appreciated!!

LITERALLY!!!