5 Tin Fish Whose Raison D'Etre Will Forever Be A Mystery

Tin Fish.
5 of them.
5cm long, 3.5cm tall.
Slightly 3D
I have lots of orange ones, not so many of the other colours, so am selling them as
5 mixed (with 2 orange included)
         or
5 all orange
Made in Japan in the 1940s or 50s.
Absolutely no idea why.
They are all a little bit scuffed
(from swimming around in a big box for the last 80 odd years)