What does a pregnant black ghost knife fish look like and what are the requiredments to take care of one?

The Black ghost knife fish (Apteronotus albifrons) has never been bred in captivity. They are known to be egg layers so they can not get pregnant. Growing very large, over 18 inches and comming from fast flowing tropical waters (about 75F) they are not easy to keep and not recommended for beginners. They also have an electical ability so may give a handler a mild electric shock. My advice is for you to look for something else to keep until you have considerable experience and are successful at keeping other easier species tropical fish.