Yes, in the example with clowns, the assumption is that the current prices of wild caught clowns is at the optimal (equilibrium) price (say $15) for clownfish. In order to achieve our goal to sell more tank-raised clowns and deter people from buying wild-caught clowns, raising the price of wild-caught clowns alone is not the solution by itself (reason provided in other thread). In addition to raising the price of wild-caught clowns, the tank-raised clowns need to come down to the equilibrium price.
BTW: Simply having a LFS raise the price of their wild-caught clowns won't work either because of competition among LFS. One guy will always undercut the other. The simpliest way to artifically increase the price of wild-caught clownfish across the board is having the wild-caught clowns taxed by the gov't.
Again, we still need to reduce price of tank-raised clowns otherwise, people will just buy substitutes if all clowns (wild or not) are $24. Now, if these 2 actions can successfully create a situation where tank-raised clowns were $15 and wild-caught were $24, we've achieved our goal. The market basically is unchanged but the ocean will benefit. People will still buy clowns as usually and still don't know or need to know where they come from.