My guy was a rescue from a 40 gallon tank. He was about 8" inches if I remember right. Its been about 7 months since he got moved to the 180 gallon and is at LEAST double in size. I feed my guy a random assortment of Hikari pellets including sinking cichild gold, algae waffers, and massivore. He will randomly get a piece of krill, chunk of shrimp, or piece of tilapia. I'm not sure flake will give him enough calories. You might want to get some Hikari sinking carnivore pellets (the small version of massivore), sinking waffers (I believe to be a small version of algae waffers) or something similar to these.
I would say that they NEED company in that they are so skittish. I do believe that they feel more comfortable in numbers. I have not yet gotten another ID, but he seems to think hanging out with the tinfoils is okay. So, given that they are very active fish, they will need ample swimming room.