> "The sandtrout ... was introduced here from some other place. This was a wet planet then. They proliferated beyond the capability of existing ecosystems to deal with them. Sandtrout encysted the available free water, made this a desert planet ... and they did it to survive. In a planet sufficiently dry, they could move to their sandworm phase."
This is from Children of Dune.
That said, what purpose did the sandtrout serve in that other place it was introduced from, I guess the early settlers weren't looking at the planet and thinking "nice place, but too wet."
Or could just be someone being stupid, like how kudzu has spread throughout the US Southeast.
https://en.wikipedia.org/wiki/Kudzu_powder
...Maybe Southeastern US chefs are creative enough to come up with a truly unique and delicious way to bite back?
The real answer to the GP’s question is that if you squeeze a sandtrout you get basically a concentrated dose of the spice.
Maybe this was expanded on post-Chapterhouse but I don't count those as canon.