If you are a beginner Aquarium Fish is good and explains things in a language you can understand, and treats everyone as a first time subscriber. An expert will get bored quickly with this magazine however because it covers the same basic ground over and over. The questions and answer usually consist of a ten year old with a Pacu, Oscar, Channel Cat and Pleco in a ten gallon asking advise on poor water conditions and you get to hear the same sermon an old women got the month before who was keeping 3 Koi in a five gallon and wondering why the water is the color of coffee.
Tropical Fish Hobbyist is more scientific and goes into very in depth detail on individual species and is aimed more for experts who have been doing this for a while. It assumes you already know basic fishkeeping, have been a lifetime subscriber, and it does not repeat itself, so you will have to look through back issues at the library from time to time to know what they are talking about. A beginner who is not into breeding or rare species may find this magazine over their head and possibly boring.