I think you're pushing it with that many tangs in a 180g. It may work out for you but odds are against it. And as stated above the Sohal and Sailfin get huge. I've got a SF in a 225g. I've had him for 2+ years, (he's about 6"), and the bigger/older he gets the more possessive he gets of his space. Although he gets along with his tank mates, anything new coming in the tank gets his attention right away. He will even attack the feeding stick or other inanimate objects. Small, juvie tangs are a whole lot different from large mature tangs. As for the Sohal, IMO, nothing less than an 8' tank will suffice. However you decide, good luck with them.
