I took a second look at the image you are not pleased with and thought it would be helpful to see one that you like as well. Some times the place or time influences a shot and viewing it at another time you wonder why you ever took it to begin with. To me the one you are showing just doesn't work (I've got plenty of those too especially being somewhere I won't be able to return to - hey, it's just film). IMO the dark area at the top is not necessary and could be cropped, the fish and sand beside being of similar tone are very similar in texture and the light stick coming to the lower right corner is distracting. The sand could be lighter in printing with less exposure and contrast and burning the fish with more contrast than the sand to make it stand out and crop so the vertical branch doesn't show.

My approach when finding a subject of interest would be to photograph it from different angles and use appropriate filters as well as no filter and perhaps with different lenses. If possible, spend time pre-visualizing what the finished print will look like. Once you have thoroughly covered your subject you can pick and choose the negatives best represent what you saw.

http://www.jeffreyglasser.com/