My Gourami's gills look red?

Any ideas to what this could possibly be? I don't think they were like this when I bought them. I recently started my first fish tank and after fishless cycling, added 6 fish to my tank ( I know now this was too many at once) and so my tank is going through a mini cycle and I am doing water changes to help lower the levels. Ammonia was at .25ppm at one time but one water change brought it down to 0ppm. Nitrites rose to .50ppm and I did one water change and added 1/2 cap Stability and they are down to 0ppm. Nitrates only have been at .5ppm.