Some of my observation :
1. When aro is under stress, it dun eat;
2. Aro chooses food if there is a choice and they can starve for quite long period just to eat the one they like.
3. Water parameters (what are the best parameters? I dun know) will affect it's appetite;
4. Tankmates will motivate them to eat more;
5. Change of environment will affect them too.