Out of 12 fries, 4 are still alive. 2 of them are sick now. I mean they haven't eaten anything the past 5-6 days. They swim through the small crushed flakes on the surface of the tank. I do a water change once everyday to be sure the water don't get dirty. The 2 who are sick are laying on the bottom on one side but none of them can swim anymore. they do twitch once in a while. I don't know what i did wrong and i need help. Is there anything i can do to save my fries? The biggest of the 4 is doing fine, his/here swimming skills are good etc. but he wont eat. (Flakes is the only food the pet-store sells)