The bottle is for the knifefish to eat from. I know it's dirty and I do plan on changing it out once I get a clear one of similar size.I have an African Featherfin Catfish and I love it. It's dorsal fin is at least an inch long along with it's tail fin. The fish itself may be 5-7" and it gets to 8". Before I removed it's favorite piece of slate for my breeder pair of Angels (The slate was near the top of the tank), I could hand feed it freeze dried shrimp. Now it hides towards the bottom at in the center, and since my tank have an 18" brace at the center I can't hand feed it without soaking my shirt and submerging my head.















