The fish died, because, using context clues, the word mournfully is usually associated with death or someone/ something leaving, and since a fish couldn't swim away, we would have to believe that the fish has died.
The prefix 'dis' means apart, away; that is to move away from something while the prefix 'sur' means over, above.
To dismount means to get off something or to remove a thing from its support. For example: The king dismounted the horse majestically.
To surmount means to overcome a difficulty or an obstacle. For example:
All the political differences between the two countries were surmounted.
B. The tone is light hearted due to words like “whodunit” and “er taste.”
