Fish excrete waste constantly just like any other living things as they swim around the water. This waste is a potential poison to fish thus it's highly essential to find a way to remove this toxin from the aquarium tank.

The process of removing this excess food, decaying matters, dangerous chemicals, fish waste products and free floating particles from aquarium water is called filtration. And the tools use is called filter.

Filters for aquariums come in all sorts of shapes, types and sizes, but they perform the same basic function, and that is to circulate the water through some form of straining or cleansing medium at such a rate that the water is kept clean physically and biologically.

Filters are categorized as 'inside', 'outside' and sub gravel; based on the location around the aquarium, but the location is not as important as the way in which it operates.

The three major categories are mechanical, biological and chemical.

Mechanical filters remove unwanted materials from the water by straining and /or the use of absorbent materials. It helps maintaining water clarity doing so.

Biological Filtration: - Unlike mechanical filtration process biological filtration involves bacteria and other microorganisms converting your fish's waste into less toxic substances through a process call cycling. Biological filter will convert your fish's toxic waste ammonia into Nitrite, and from nitrite to nitrate, which is relatively harmless. This cycling reduces the required maintenance in your aquarium. Chemical filtration as the name implies can remove toxins and other chemically induced material from your aquarium system with the use of activated carbon. It's necessary to change activated carbon should be changed often to have a save community.

How Poisonous Substances Your Aquarium Can Cause Fish Death

Aquarium water becomes dangerous to fish when its over-saturated, as a result of nitrogen cycle in the water. In this short article, we shall look at the causes and the simple way out to limit continuous death of aquarium fish.

As we are all aware, atmospheric air is made up of about 23 per cent oxygen and 76 per cent Nitrogen together with host of other gases in very minute quantities. It follows that when we put on the airflow system of our aquarium, the air pumped in contains a little oxygen and a lot of nitrogen.

This atmospheric nitrogen can lethal to fish when the water is over-saturated (over 100 per cent) saturation with this gas.

Research has shown that nitrogen embolism otherwise known as NITROGEN GAS BUBBLE DISEASE can occur with 103-118 per cent nitrogen saturation and cause a lot of fish casualties.

This condition can affect an aquarium fish when one is replacing the old aquarium water with slightly warm fresh water. The infection is characterized by the presence of small bubbles of nitrogen beneath the skin in the fins, tail or mouth, behind the eyes, and in the blood vessels.

One can prevent the disease by aerating the water to be introduced for a while in order to clear the excess nitrogen. Affected fish would be placed in a small bucket of water into, which has been passed an airstone device to properly aerate the water. The fishes are bound to recover spontaneously if the aquarist takes an immediate remedial action.