A lot can be conveyed in a story. Themes, lessons, adventures, trials, tribulations, emotions, and anything else you can set down in words, really. But there is a difference between what you write, what is read, and how it is imagined.

As the writer, you have the most control over just what you write. Sure,  editors and publishers may try to muck it up a bit with their own opinions and rules, but you're the creator and have the right to write what you want. (Unless you sell your rights, in which case you should headdesk until a new idea comes to write about. If it takes a while to get a new idea, insert a pillow between the desk and your head to prevent biological data corruption.)

As for what is read, you have some control in who you personally give your writing to, and who you personally market your writing to. But once it passes out of your hands, it becomes akin to a paper plane, subject to the whims of the wind currents, gravity, and the quality of your design. You can't always pick who your readers will be, and that's a good thing.

If you publish your work online, any reader with an internet connection and a bit of Google-fu can read your work, and interpret it as they please. The same effectively applies to printed matter, depending on where you distribute it.

And once your writing is in the hands of the reader, you can't control how they're going to interpret your story. Every person's perspectives are unique, due to their unique life experiences and corresponding opinions on the universe. You can craft your writing to lead them towards certain conclusions and certain images.

For example, having a blonde haired main character usually results in the reader imagining some character with blond-ish hair. If the reader imagines a character with purple-y blue spiky hair with sparkles in it...you need to work on your character descriptions.

By choosing your words carefully, you can better guide your reader towards the interpretation that you want them to imagine. With flash fiction though, that's pretty darn hard. Telling them that Character Q is hunting for alligators in trees will be interpreted in as many ways as you have readers. Telling them that a devilishly handsome man in a faded orange fedora is questing for the elusive tree climbing alligator of Katesh in the desert lands of Pineapple will still be interpreted in as many ways as you have readers. But the first version trims down the word count.

If there's specific imagery you're aiming for, then by all means, work it in as best you can. But for the more mundane bits and pieces, it's okay to leave them hazy and open to wider interpretation. Readers are willing to let their imaginations work for them to fill in the gaps.