I read somewhere that you can use broken coconut shells as natural looking hiding places for shrimp and small fish. I recently added a piece to one of my 10 gallon tanks, and the water is slightly tinted. I boiled the shells twice to get rid of the tannins and it seemed to work because the water they were boiled in looked like tea. Honestly, I kind of like the color the coconut shell gives the water; I think the slightly darker water provides a nice contrast for brightly colored fish and makes them stand out more. Can the tinted water hurt the fish?