Incognito, in regards to krill, I have read something that may make sense. Krill mainly feed on seadweed, which is high in iodine. High concentrations of iodine cause problems in fish, obviously. My lion developed lockjaw and had a hard time going after food. The first symptom I noticed when the "yawning" and the lack of ability to retract his mouth. I would have to help him close it. My lion was very odd and trusting, he would lay his spines down at feeding time and acted more like a puffer in regards to "friendliness." But anyhow, soon after, he had a hard time opening his mouth and couldn't eat. I could only resort to squeezing a slurry of cyclopeeze and selcon into his mouth. He only lasted about a month of that before he died. If my voice could be heard, I would remove all krill from their diet too. I have read about others that experienced what I went through too, and most of them all said "all he ate was krill."