A strong filter is a must. Any tank is going to feel small to them, as they migrate in nature, so they at the least need a lot of current. Also they eat a lot & sorry, are not scavengers, meaning they soil the water quicker than others. Mine are about a year old & 5 inches. They need at the least one companion, don't keep it on its own. Also, once you have set up a brackish or saltwater tank be sure the other tank mates are not small enough for the catfish to eat. (This might make for a sad wife ; ) Mine are stuck on blood worms & are extremely finicky now that they are accustom to what some people call a "treat" food. They will however sometimes eat frozen minnows. Also, be careful not to let these guys catch ick from other additions to the tank...their skin is extremely susceptible to the parasites & harder to cure.
Hope some of that helps!
Good Luck!!