Help with a Japanese joke: the link between メダカ and 小学生


I was playing my Japanese version of animal crossing new leaf and when I
caught a Killifish the dialog said:

> メダカを 釣{つ}り上{あ}げた！ まだ小学生{しょうがくせい}だな

I get the gist of what it says but I think it's some sort of joke as is the
custom when you catch something in the English games. Would anyone be able to
explain this joke (if it is one)?




I think it's a reference to a famous children's song めだかの学校, where a school of
めだか is...er, a school of めだか.

短い答えでごめんなさい。

