My 2 year old oscar hasnt eatin a lick in 3 weeks started out spitting food out to not eating at all .Its a 100 gallon one 12 inch 0 8inch red sev 5 silver dollars. the water was tested everything is o exp nitrates 20 tank has 2 rena xp3 and one emp 400 .I started doing 50 water changes every 3 days added salt and i used parasite meds with no help to my poor o .Hes not gonna last much longer so please give me a hand and info or advice dont want to loose my little monster .