+1Congrats on starting out with your first Polypterus!
Bichirs have a very strong sense of smell, so blood works is a good choice to start, but I personally like to feed crushed up hikari carnivore pellets and/or finely chopped bits of raw shrimp or tilapia.
As it gets more size on it, it will hide a lot less
It will fill out quickly apparently. I don't have enough experience to say but I have heard they grow very fast when small