I recently bought a jar of these (along with krill and plankton) from the pet store. I'm pretty sure these guys are safe, as the info on the jar was very encouraging, but please let me know if it isn't. Tubifex Cubes Freeze Dried Food Guaranteed Analysis: Min. Crude Protein 55.0% Min. Crude Fat 5.0% Max. Crude Fiber 5.0% Max. Moisture 9.0% Min. Phosphorus 0.9% Ingredients: Freeze Dried Tubifex Worms Only.