What dose a shark - catfish need?

okay a place i worked at is selling there store and gave me there fish take (Extremly dirty ) anyways i cleaned it up really good but it has no rocks or any deco and on the front was a sticker that said "Shark catfish - Hexanematichthys seemanni" and 3 of these fish pritte small that look like sharks with wiskers. anyways i need to know what i need sand or rocks and what decos would go best like plants or stone things anyone know what i should get? the fish are doing fine other then a blank aquarium.