Hi everyone! I have 6 gal tank with four zebra danios and one blue danio. This morning I put some tropical flakes in the tank, they only took couple of bites and got back to chasing each other. Now that is unusual, my danios never turn down a meal, they gobble up their food witin seconds. They seem happy, water parameters are perfect. They are also keep eating something from the gravel, but I took magnifying glass and couldn't see anything