My DPs loved like blaclworms, but were a bit spoiled. They watched the cones and if the worm was not wiggling out, they would not touch it. Those and small ramshorn snails were their primary diet. They did not crush the shells - ramshorns tend to expose more of their foot than most snails, so the DPs could trail them around and bite and slurp as loaches do.
Where's the fish? - Neptune