Yes, any metal in the tank will affect your shark especially if it is a bi-metal like a coat hanger. There is a reation with bi-metals placed in saltwater that causes an electro-chemical reaction that will screw with your sharks ability to not only find food but to swim in the correct manner and its behavior. This will also cause your shark to go into an "off- feeding" phase. My wife was feeding my Banded Bamboo for several days with a coat hanger without my knowledge and the shark stopped feeding, since I work extremely long hours I was not aware of the issue in time to make a difference I had to discard a dead shark this morning after trying for over a week now to get it feeding again. Note: I have also been seriously flamed in another forum for having my shark (a 5-6" Bamboo) in a 75 or even a 125 gal to start and was told I was being inhumane to the animal.