I've been feeding my fish almost exclusively frozen bloodworms for the past two weeks or so (but recently I've been giving them Tetra cichlid sticks). Here's the problem: my largest Salvini at almost 3" began excreting white, stringy poo today. However he has no lesions on his head. He's definitely eating very little (if at all) now. I've heard that too much frozen food can cause digestive problems. Is that what's happening to my Salvini now? Note that only the largest Salvini has this problem - the other two, which are around 2" in length, are fine. Filtration is more than adequate and I just did a 35% water change four days ago. The Kribs in the same tank as the Sals look perfect.