I'm a bit late on this
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Angelfish are in the cichlid family but on the scale of agression, they are on the lower end of the scale. Knowing what the cichlid is will help in determining if it is the culprit. If they are African cichlids, then yes they are the aggressors.
Water chemistry is very important to know. Having a "new" aquarium and stocking with that many fish in the beginning will be challenging. If fish is something that you will enjoy and want to learn more, look for aquarium clubs in your area and on-line fish/aquarium forums. There's tons of info out there.
HTH