I actually don't think I can confirm this.
I'm checking the maps in rpg maker right now, and I see no way to access any of the water at that current point in the game in Citrine Mountain. The only portion of Citrine Mountain you should be able to access right now is the portion south of Shades gym, past the rock smash rocks.
This is just my uneducated guess, but I'm going to assume that perhaps someone thought that you could access the area on the map circled in red at this given time for whatever reason(at a glance it probably looks as if you can just run down the stairs and access the water). You shouldn't be able to fish in Citrine Mountain for quite a while(first chance should be once you get locked out of Agate Circus).
If my assumption is true then your next earliest chance at Clauncher would be in a portion of the Celestinine Mountain when accessed through the North Adventurine Woods(after beating Serra and doing a bunch of a story).