I have an almost 4" jack has lately no been eating and has very scared and hides so I did a water test and nitrates were high so I have been doing water changes and my nitrates are pretty low but he won't eat still. Can anyone help. I don't know why my nitrates were up cause I always do weekly 20% water changes and he is only in with 7-8"oscar and a 3" meeki in a 55 soon to upgrade. Is there a reason why my nitrates went up