What is wrong with this Neon Tetra?(picture)?

every week is unnesasary, about 40% water change a month is better, and what other fish are there in your tank? and tetra are shoaling fish, which means it's best to have them swim around in a group of the same type of 6 or more, so best to make sure you surrounding fish aren't fin nippers, that you get some more neon tetra's and to make sure that the temperature is right too! about 25c is the best idea for these tropical fish. Hope i helped :)