in your aquariums, do you prefer Tropical or Saltwater fish?  

While I love the bright colors of the saltwater fish....I do not have any at this time....it is a lot of work to maintain. We do have a frshwater tank...it holds my sons fish and he take care of them each day...every month we vacuum the gravel to maintain a clean tank...he makes a huge mess usually, but he is 5...so that is expected...we always do this together and we benefit from the closeness of spending this time together.

I think that it is important that a child, if they have pets, take care of these pets and the parent should be helping them figure out how to best work this into their daily routine......

I have an aquarium of tropical fish. I think the saltwater tanks too much knowledge and skill to keep the salt balance just right.
I have several pineapple tetras, two platys and a cory. I had more, but a bad bout of ich depleted my tank. I want to get some more fish, but want to be sure the ones I have are healthy first.

Awww don't give up on the idea of a saltwater tank! It sounds like you're one of the people that would actually do it properly and be a great fellow hobbyist! Yes, I have a 130 gallon saltwater reef tank, worked as a fish specialist for a local store, and have taught many people how to successfully keep saltwater fish! If you go to www.saltwaterfish.com they have a message board with some really knowledgable and friendly people who would help you figure it all out too.
Really the main bad difference between a freshwater tank and a saltwater tank is the cost. The fish are more expensive, must be chosen as carefully if not moreso for compatibility/water requirements/etc., and some of the equipment is much more expensive depending on what you get. The maintenance is essentially the very same! Do a partial water change at least once a month with a gravel vaccume. The only difference is you add the salt to the water and use a hydrometer or other device for measuring the salinity. Hydrometers are actually very simple to use! You just fill it with water, tap out any air bubbles, then read where the pointer is pointing. Add salt if the salinity is not high enough, fresh water if it's too high, simple!
For beginners I heartily recommend a 40 gallon or more (realizing that the bigger you get the more expensive it will be in the end) FOWLR tank (fish only with live rock) and some of the tougher, smaller varieties of fish. Live rock is attractive and extremely beneficial! It gives a more natural look to the tank which is pretty and homey for the fish, it houses beneficial bacteria essential to the nitrogen cycle so acts as a biofilter, and introduces various organisms into the tank like "pods" (teeny little crustaceans which are a natural food source for the fish) and, if you're lucky fun creatures like feather dusters! There's a variety of beautiful fish that would be appropriate for this size aqaurium too like clownfish, damsels, royal gramma, many gobies and blennies, etc.
You use the exact same kind of heaters in saltwater as fresh, the same kind of florescent lighting if you stick with fish only, and you can use the same kind of filtration. Many saltwater enthusiasts get into some pretty complex filtration and I don't recommend a undergravel filter with these but for a smaller tank a biowheel power filter would be a fine one to use, just as one example. Cannister filters are another filter that might be familiar to you and can be used in saltwater. Many people recommend using a protein skimmer along with your filter which freshwater hobbyists might not be so familiar with but it's effective and as easy to set up and use as any filter! The substrate is the last difference. You can't use freshwater gravel and instead use crushed coral or marine sand.
Saltwater tanks really only get the most expensive and touchy to maintain when you add creatures like starfish, anemones, corals, and the like. These animals have more stringent requirements! Most of them require very pristine water conditions requiring more partial water changes and/or multiple filters/more complex filters. Many of them are also photosynthetic like plants and to survive must have upgraded, more complex, more expensive lighting such as actinics, metal halides, etc.
I really adore keeping fish and helping others be successful in the hobby! If you'd like to try saltwater please visit the message board I mentioned earlier and/or don't hesitate to contact me!! I'd LOVE to help!

related resource: air filtration

I would LOVE to have a salt water tank. But the start up costs are so expensive. They are so pretty to look at though.

My sister has one where she works right across the hall from her desk. Lucky her. I get to stare at a bamboo plant on my desk.

If I did have an aquarium it would not matter what type of fish that I had in there. I think all fish are beautiful though I know that they all do not get along with each other. My neighbor and friend has several aquariums. I am not sure if they are tropical or saltwater but they are nice to look at and they get along great.

Both are Beautiful. And yes a tropical tank is easier. A salt water tank isnt that hard its just more expencive for everything and fish.