Simone- Okay, Dude. How do you determine that fish have a calcium definciency? Not being critical, I really am curious about how hobbyists figure out stuff like that. Years ago, I noticed that my killies had better finnage and slightly brighter colors than those of my local killifish- friends. They were feeding straight live and frozen brine on the decision that it was some kind of perfect food. I was feeding frozen brine in the afternoon, and flakes in the morning. Fish in the wild do not eat exclusively eat only one thing, with the exception of certain specialized salt-sater species. And even people can not be as healthy on any one kind of food as they will eating a balanced diet. My apistos thrive on quality flake and even spawn on it. I have gone weeks at a time on just flake, although I prefer to also feed frozen and occasional live foods. The advantage to quality flake food is that it is formulated from a variety of natural food sources, and is better balanced than brine, although its protien content may be a little low. Why not include something besides brine, and balance their intake a little. THen this problem will probably go away. Bob