Why rock surface matters
Paint, sealants, and unknown coatings can make decorative rocks unsuitable for a shrimp tank. In a shrimp-focused aquarium, the choice should also support steady routines, visible livestock, and access for basic care.
Before you act, check whether a finish is present, flaking, or absent from the product description. Compare the item with the rest of the setup and note any recent change that could affect what you are seeing.
A careful way to proceed
choose uncoated aquarium hardscape with known material details. Make one adjustment at a time and watch how the aquarium responds during normal observation.
Avoid scraping a questionable coating and using the rock anyway. Labels, products, and tank conditions differ, so use a reliable guide as context and record what you directly observe. If uncertainty remains, ask an experienced shrimp keeper before making a consequential change.
Use these as general hobby references. Test your aquarium and confirm product guidance before making changes.