First time to post and have a question concerning my GT he is not eating well and spending a lot of time hiding and close to the bottom. Have a 65 gal tank . Checked my parameters and ph is 6.5 hardness is 30ppm and nitrites are 0 ppm and nitrates are below 20 ppm . Did a 20 gal change yesterday and he perked up some but still did not eat as usual. Today I noticed he has a reddish tint inside his mouth and he is keeping it open . Any thoughts ?