How can I trade fish/bugs between characters?

Something I did in the first Animal Crossing was make a house on an alternate character solely to showcase bugs/fish I felt were too cool to only leave in the museum. However bugs can't be mailed or dropped, so I'm at a loss as to how to do this.

Is there a way I can give bugs/fish to a second character or will that character have to find them themselves?

You cannot place bugs/fish on the ground outside. You cannot mail bugs/fish. You cannot display bugs/fish in Re-Tail. As far as I know, these are the only ways that you can transfer items betweens players.

So, based on this I would say that it is not possible to trade bugs/fish between players.

I don't think you can trade between characters unfortunately. Each individual will have to catch each bug/fish respectively.

You can't mail fish or bugs, hence you can not buy it via streetpass because the item will be sent to you via mail.