This post was inspired by something I learned today, which is why the Chinese word for "good fortune" is sometimes hung upside down.
The Chinese have some nutty superstitions based on words sounding alike. The best known of these is probably that the number 4 is considered unlucky because it sounds like the word for "death".
This "reasoning" is especially silly in the Chinese language. In Chinese, every word has one syllable, and there are a limited number of sound combinations that form valid words. For example, in Mandarin there are words that begin with a "k" sound, but none that end with one. So of course every word is going to sound like a whole bunch of other words, in Mandarin more than most other languages. If you're going to use guilt by homophonous association, EVERY word is going to have a hundred layers of meaning that have nothing to do with the word.
In the case of Chinese tetraphobia, the "logic" is especially silly because the words for "4" and "death" don't even have the same tones.
If you want to be logical about this, I'd pick a language like French, which has a tiny number of homophones compared to Chinese, and I'd look for multiple corroborating word associations, not just one. For example, in French the word for fish is "poisson", which sounds suspiciously like the word "poison", meaning "poison". Furthermore, the word for "fisherman", "pêcheur", sounds suspiciously like the word for "sinner", "pécheur". So there you have it: FISH IS EVIL.