rarefish has XX chromosomes

. Stats:
Nitrate: 10
Nitrite: 0
Hardness (GH): 15
Alkalinity: 180
pH: 7.8
Ammonia: 0
I know it's not perfect, but it's much better than it was.
Routine: every 1.5-2 weeks I clean the gravel and do a 25% water change. I add either Amquel+ or StressCoat. The power filter has a Lustar Filter-Max III Prefilter (sponge) on it that has been on it for about 18months, so I don't use carbon. Can someone enlighten me as to what "OTS" is? I don't think that I've ever heard of it...