HI I am wanting to get some NLS food for my fish but don't know which is best. I have mollies, guppies and 1 peppered cory in one tank together. What would be best for them? What size being the guppies mouths are so small? I also have blood parrots. What would be good for them and what size? The parrots range in size from 2 inches to 4 inches. Also what does thera A mean? Thanks much!