Hi, i'm pretty new to fish keeping but I'm learning! Right now I have a 20 gallon aquarium with 1 male sunburst platy, 2 male fancy guppies, and 4 zebra danios(that I am possibly giving to a friend due to agression with guppies). Last night while feeding I noticed my danios had some redness where their gills are. Upon research I read that ammonia could be the cause, but I quickly checked my water and its at zero. My tank reads 0-ammonia, 0 nitrites, and about 10- nitrate. But my pH had been reading about 7.4 for a couple weeks but I just checked it again and its reading 8.0-8.4! Could that be causing my danios red gills? How can I get the pH back down? All my fish are acting fine, and all are eating well.
Thank you for your help!