While we're nitpicking, unless you have partial eels, it's arbitrary number, not amount. That calls to mind measuring blended eel, of which I don't want to make a career.
Well to be fair the saying doesn't specify the state of the eels.
It could be liquefied remains of eels! Although I'm guessing we would need to study a few of the translations in languages that explicitly differentiate between "a collection of whole somethings" and "an amount of something". Although now that I'm thinking about it in english saying "my hovercraft is full of eel" would imply that it's an amount of eel, not a distinct number of eels.
Still, if it were the "amount", a simpler JS expression would convey the message:
