Hope you enjoy the world of keeping polypterus. Any FW substrate is fine as these fish can thrive in harsh conditions, hence the adaptive lung mechanism...btw leave room at the top of the aquarium for the fish to breathe air, regardless of aeration. Feeding all depends on how quickly you would like the fish to grow and its tankmates. P. senegalus enjoys live food when available, such as guppers, rosies and comets, but you will find it is not the most adept hunter on its prehensile fins. Beefheart will encourage some quick growth if thats your goal, bloodworms work well for young polypterus. If the fish is finnicky you may have to use some tongs or tweezers to initiate interest in front of the fishes face. Either way, bloodworms, beefheart, rosy reds will all do as more than adequate food sources. Try to wean on freeze dried or packaged foods early and wave around using the same methods to try to entice it to eat, is thats the route you'd like to take. Once reaching a decent size, the fish will accept all kinds of food. My senegalus is around a foot long and eating feeder comets, krill, beefheart, bloodworm blocks, and clams. It is very important to provide adequate nutrition for these fish to get adequate sized however, so make sure you supplement their diet accordingly.