Huh. That's exactly how you make garum - an unpleasant horror of mashed fish. Refer to Max Miller and his spectacularly successful effort to reproduce Garum in his back yard.
There are folks that will insist that we don't know at all what Roman garum really tasted like or everything involved in its preparation, and they're not exactly wrong since Colatura di Alici can only be traced back to the middle ages, but it's also oddly obtuse. I think it was probably like modern fish sauces but Roman garum could have been as different from Colatura and Asian fish sauce as those are from Worcestershire.