It's a fantastic hobby if you're at all into biology, chemistry and beauty! (electrician and plumbing skills also come in handy ) "Tis a tad expensive though, and definitely labor intensive. But sooooworth it! And if you think the fish are great, you should see the corals. I got into it from being a scuba diver.
I'm a freshwater guy myself, currently have 4 tanks setup, and getting ready to put my old whisky barrel outside for the summer. My 75g is a planted aquarium, with featuring South American tetras, some of whom rival many saltwater fish for color. Only problem is, I ran out of CO2 a couple of weeks ago and I better get a new tank or I'm going to lose half my plants.
My son and I keep a 55g for native fish. We catch minnows, darters, catfish from local creeks or streams. Some of these (rosyside dace) have really nice color during spawning season, while others have spectacular finnage (satinfin shiner).
We also have a 10g with a breeding pair of killifish in my daughter's room, and a 20g with my son's favorite things in his room.
I agree with you, that keeping fish is a very nice blend of biology, chemistry, even plumbing and electrical type activities. My next project, is I'm ripping out the insides of the standard flourescent light fixtures, and upgrading with a highly reflective background and thinner bulb, the result of which will be more than a 100% increase in output, to benefit the plants.
And Sens, aquarium photography is a whole niche unto itself. Ever try to capture a live subject with digital lag to overcome? Arghh!
EDIT: I also belong to two related clubs, though not especially active (especially during baseball season)http://pvas.com/index.htmhttp://www.gwapa.org/