In the original image, the fish simply looks at the hook with the text "This is b8". Later variants became more like macros, expressing the otherwise unspoken sentiment of the poster. Due to /tg/'s tendency to openly discuss topics with (at least more, compared to other boards) civility, as well as the uncanny knack of /tg/ Anons at turning bad trolling into a legitimate discussion of something from variations of spears to the finer points of 17th century music to how many spiders a Drow could fit in her vagina, the meme was particularly useful on the game board.
Due to the simplicity of the image and the onset of summer months on 4chan, the meme exploded into hundreds of variants, with many referencing specific works or elements of board culture.
Bionicle fans are not easily b8ed.