I received two emails of posts to this thread, one is showing here (#3) but the other is not. I will respond to your comment in the missing post just in case.
Mixing various brands/types of food is not advisable. This does not mean it will cause any direct harm to the fish, but the reason for using different foods is to ensure a better diet but also that the fish are eating it. Some fish do not like certain foods, just like humans. Only giving them one food a day means they either eat it or go hungry; going hungry is not going to harm them either, for a day or even more, but they are more likely to eat what you give them if there is not something "better" available.
The reason I do not recommend Tetra foods is due to the additives; these are frankly not that good for fish. Here again, they are obviously not going to die from less-healthy foods, but fish nutrition is rather complicated and we want the healthiest fish to be able to fight off other issues. So good foods are important, and filling them up with cereals and meals is not the way to go. I only use one such food among my others, as it has earthworms and the cories love it, and once or at most twice a week is not going to cause harm like feeding every day with additive-foods could.