Here's why:
* Short vowels are typically found in words where the vowel sound is quick and sharp, like in "cat," "dog," or "bed." The vowel sound in these words is short and doesn't have the "long" sound.
* The vowel sound in "fish" is a long "i" sound. It's similar to the "i" in "bite" or "kite."
Therefore, "fish" has a long vowel sound, not a short vowel sound.