Feeders do not cause drop eye, but it is always a good idea to get your aro on some prepared food for convenience when he is larger and a mixed diet(you can rotate feeders if u like as long as he doesn't get picky) is always best.
My 10" aro eats hikari aro sticks, freeze dried red shrimp, fishflies, and crickets that are fed powdered veggies. His growth rate/color has been phenomenal! I may add superworms and the odd pinky mouse to his diet soon.
BTW, pics look like he has cloudy eye, but it's my crappy camera...
I fed my silver aros crickets alot together with market prawn - they get massive in no time. I see nothing wrong with feeding aros with crickets as long as they are farm raised or personnaly raised (i got both now)
get him on hikari floating pellets now - they are quite animable to them when young (in my experience)
U won't need to worry about a large tank for awhile i think. I currently have a puny black aro in a 6' aquarium - it looks ridiculous. Even with separator he jumps backwards and forward. i am not so sure that givign a puny fish a large aquarium is such a good idea. BUT be ready to move when the need calls , that is, have a larger tank set-up and cycled
I was actually looking into getting a couple fresh water stingrays once we upgrade. How are they as tank mates? IIRC, i read that sand and arows don't go well together, they may be top dwellers something about the left over food getting buried and rotting or I may just be making it up. I don't want just the arow in a 300G tank, I'd like to have similar "biome". What tank mates go well with arows?
On to food, For now I am going to continue giving him the powder boosted crickets and start giving him shrimp and Hikari sticks. Leaning him off of the crickets over time into a more meaty diet.