Cleaning your tank regularly removes toxins that the fish excrete naturally. With out regular maintenance a fish tank can actually kill the fish in it. Here are some tips to keep your fish healthy.
1. Only replace 15% of the water at any given time. There are natural organisms that grow in the water that act as a natural filter
2. Leave the plants and decorations in place while cleaning, this is where the beneficial organisms live too.
3. Leave an air gap between the water surface and the lid on the tank. Fish need to have the oxygen circulating in from the surface to breath.
4. Use a chlorine remover when you add fresh water to the tank. Our tap water contains chemicals that are a low level toxin to humans, but for fish can be fatal
5. Over feeding or over population can make a tank tedious to clean.
6. Spread the gravel at the bottom evenly, but leave it thinner in the front so you can see the waste build up and know when it's time to clean.