i just bought a black mmor fish, and obvioulsy i want it to live. i previously bought two of them but they both died. right now its in a one gallon tank with nothing but a gravel at the bottom. im so worried right now for the little fish, wondering if i am taking care of it right. what do i need to keep it healthy? what kind of filter can i get for the one gallon tank? what kind of fish food? and what other fish can i keep it with?