yes, that's what they look like to me, too. They can vary in appearance. As for feeding them to the brevi's I don't know if they move around/quick enough for them to bother with. Once aphids start sucking plant juices that's pretty much where they stay. If your brevi's don't eat them they will quickly infest the plants in the tank so it probably isn't worth it.
One other concern might be that they produce a sugar-like secretion referred to as honeydew (this is why you often see ants around them. The ants get the honey dew in exchange for protecting the aphids) and I don't know if it would be a problem for the chams or not.
just my buggy 2 cents 
lele
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0.1 veiled - Luna
0.2 house geckos - Gaia & Tia (MIA 
0.2 felines - Kyndra and Líta