Ive had 3 for a few weeks now and a few days ago 2 of them started acting funny swimming sideways and scratching the rocks and their stripes have faded, then one died yesterday and today the other was lying upside down on the rocks but then swam away normally when i approached the tank and appears to be fine now. Water conditions temp:84 and ammonium, nitrate and nitrite all were fine, anythoughts? please help!