Get the fishing rod. Use it on one coast or the other (or at the end of the dock). Wait until it says "there's something on the line," then hit c (it has a c tooltip). It may catch immediately, or say wait for it, if it says wait for it, wait until it says pull now and hit c again. If you hit c at the wrong time, it'll get away, otherwise depending on the difficulty of the fish, you'll eventually get it (I think coral cods can take 3-4 pulls).
Get the fishing rod. Use it on one coast or the other (or at the end of the dock). Wait until it says "there's something on the line," then hit c (it has a c tooltip). It may catch immediately, or say wait for it, if it says wait for it, wait until it says pull now and hit c again. If you hit c at the wrong time, it'll get away, otherwise depending on the difficulty of the fish, you'll eventually get it (I think coral cods can take 3-4 pulls).