I have an otocinclus that is lying on the bottom, swims a bit erratically, and is lethargic. Temp is 78. Tank is cycled, I inject a lot of CO2, but oxygen isn't an issue as plants are pearling, and his belly is round so starvation isn't an issue either. Ammonia is 0, Nitrites are 0, Nitrates 30-40ppm (hard to read the exact shade on the API kit, lighting in my house isn't the best). Three other otos in the tank are doing fine, and parasites shouldn't be a culprit as I have been dosing Metroplex for over a week. Whole tank was in rough shape yesterday after a nitrate spike, performed emergency 50% water change. I'm not EI dosing anymore, this is the second time I've had a nitrate issue, but luckily didn't lose anything this time. I can't do a water change at the moment.