i dont know whats going on with my tank...ive quarantined the neons already and now yesterday morning i woke up and looking at the remaining fish (which seemed to be healthy as of yesterday) i realised that now one harlequin rasbora is really swollen...literally she or he looks like a hatchet fish...so i fed them peas yesterday but today shes still the same...the scales ARE NOT sticking out and she doesnt have trouble swimming...she eats fine too...ammonia and nitrites are 0ppm...nitrates are 5ppm and pH is 7.6...i returned the temp back to 79-80F over a week period....i changed 50% of the water on wednesday when i transferred the neons to the 10gal QT...i havent added anything new to the tank since i first set it up almost a year ago...what should i do??? i have the QT with the neons already so....why oh why