No, TFA was a little vague but there's no collision. The kanji for mackerel 鯖 is a standalone word/idea, whose graphical representation happens to consist of th

No, TFA was a little vague but there's no collision. The kanji for mackerel 鯖 is a standalone word/idea, whose graphical representation happens to consist of the characters for "blue" and "fish" next to each other. But virtually all kanji are constructed this way, so native readers just see the overall word without considering the parts, similarly to how you'd read the word "notable" without mistaking it for "not able".