I read the thread and not too sure if you said you changed your waterchange routine...but I did see you filled your tank 7inches and then started to do 1inch water changes.
I would stop this. Aros love clean water and lots of it. Personally I would just fill the water to the top and cover all openings on the top of the tank to prevent him from jumping out. If you want to leave the water an inch or 2 down from the top, you could go that route too if it makes you feel comfortable...But I would certainly put more water in that tank.
Also quit these little waterchanges! I would do 50 to 70% every 4 or 5days to maximize success with your aro. Aros are super tough fish. They will be able to handle these size waterchanges easy with most peoples tap water
Use low lights..as low as possible now as you want him to get in good form..which right now, he's prob too stressed to swallow food
I would keep using just the sponge filter till he starts eating and gains some strength. Once he starts eating, you can utilize the powerfilter. But if you think the current is too strong when he's ready and he's blowing around.. you may have to downgrade powerfilters for that length of tank
But again..fill the tank, do monster waterchanges, and keep low light. He should not need the plastic plants, I don't see a need for them for his health..tank aesthetics reasons only I would say
An aro of 5 to 7inch can go a decent amount of time without of food. I wouldn't worry about him starving to death.. till you get his tank and water to his liking...crickets, superworms, small whole frozen fish like anchovies and small herring are healthy..Cut the fish up into pieces if needed. Market prawn is gd to throw in the mix too. Ordering some hikari food sticks can work as well