Have you visited or lived in a big city where the air was full of smog? That is what it is like for your fish when their water is dirty. They breathe the water in and out and whatever is in the water is going into their little lungs!
If you have a small fish in a little fish bowl it only takes a couple of days for the water to become completely inundated with old, rotten fish food, urine, fish droppings, and whatever else gets into the water. Due to the nitrogen cycle - this turns into ammonia.
Can you imagine inhaling ammonia? It would kill you. This is obviously what it does to your dear little fishies, too. This may sound harsh, but if you understand this fact, it will save you a lot of grief in the future.
Keep your fishes' water clean and they are much more likely to live a long and healthy life.
It is a little difficult to keep the water in a fishbowl clean. You really need a fishtank with a filter.
With a fishbowl, you will find yourself cleaning the bowl every couple of days and this is also hard on your poor fish to be dumped back and forth to clean his bowl.
Get a fishtank and the filter does some of the work and then your job is to do partial water changes on a regular basis depending on the size of the fishtank.
Once you have had fish for some time, you will start to notice this. When your fish are fine, they usually appear to be happy - swimming around with vigor and excited to see you. If you observe that your fish seem to be feeling down - it will usually have to do with not feeling well, and the answer is almost always a problem with their water quality. There are other issues related to water quality, but the main idea is to keep the water very clean. If you only have a bowl, it is rare that fish can survive and thrive in this environment for a long period of time.
The water quality, for one thing, is too difficult to maintain in a fish bowl. If you want to bring your fish home in a fish bowl, you could start with that as you are setting up your fish tank. You just have to be sure and keep the water cleaned. Be very careful - you CANNOT use soap - not ever.
There are many different types of fish tanks to choose from. Please see articles here at the Fish Site at BellaOnline.com in which I have reviewed various fishtanks. The size of the fishtank depends on the size and type of fish you choose to make a part of your life.
Basically, a rectangular fishtank is better because fish usually swim horizontally. This gives them more room to swim normally. They need room to exercise and have fun and room to grow! You'll want to get a tank that is fully equipped with everything you need like a filtration system and aeration! Find a tank that is big enough to add plants and toys that your fish will enjoy. Maybe you will choose a treasure chest or an underwater diver to enhance your fishes' daily life.
We owe it to our fishy friends to give them the best possible life we can and clean water is the basis of a long and rewarding friendship with our beloved fishies. Kindness to animals promotes kindness to our fellow human beings.