I have a 29 gallon with 2 bolivians, an appistogramma cac. and a checkerboard.. yes it's a volatile combination but they haven't gone to war quite yet. My question though is about cleaner/ghost/cherry shrimp. What is their purpose in the tank? I've got a lot of plants. Do they take care of waste or algae? Also can i mix multiple species of shrimp? cherry and ghost? Do the fish ever have problems with them? Finally do I have to consider them as fish regarding space?