Hey i have had my tank set up for 2 to 3 months now. All of my levels have been great. Right now all I have is a marble cat shark. I have been trying to find his favorite food (silver sides) and have been trying squid and shrimp. He did not eat the squid or shrimp so I only left the food in for 12 hours and took it out. I guess I left the food in too long because it raised my nitrite level to 0.25. I of course want that level to go down completely, so what is the best way to get that level to go down? I would prefer to not add any chemicals. Would water changes do the trick? I am going to wait a while to try the other kinds of food again. It is a 125 gallon tank, 79-80 degrees,=.