The most common cause of death in aquarium fish is disease. This accounts for more tank deaths than any other cause, but its something you can easily avoid. The predominant reason for spread of disease within tanks is poor water quality. There are several factors that can contribute to poor water quality. These can be over-crowding, irregular cleaning or placing too much food in one tank for the amount of fish present.

Another cause of disease can be buying an already-diseased fish from a store and entering it to your aquarium to spread to your previously healthy fish. Before buying any new fish you should always check the condition of all the fish within the tank before you make your selection. No matter how healthy the fish you purchase might seem, if another fish in that buying tank has a disease then it could potentially spread to all other fish.

Typical Aquarium Fish Diseases:

Fin Rot: If you notice any of the edges of your fishs fins beginning to look frayed or jagged, then your fish may have fin rot. This bacterial infection usually afflicts injured fish with suppressed immune systems or sometimes stressed fish living in overcrowded conditions.

White Spot: White spot shows as tiny white dots on the body of your fish. These little dots are actually parasites called Ichtyopthirius. They nibble away at the flesh beneath fish scales making your fish very ill and possibly even induce death. If you notice one fish within your tank with White Spot, its important to isolate that fish and clean the tank properly to avoid other fish becoming infected.

Hole In The Head: This aquarium disease sounds as though youll be able to see clear through the other side of your fishs head, but in reality Hole In The Head usually appears as little dimples or dents within the scales. This is most commonly caused by a too-high level of nitrates in the tank water. Test your water regularly and be sure your nitrate levels are correct for the size and volume of your tank.

Fungus: Fungal growths often appear in fish as fine little fluffy bits of cotton growing around wounds or injuries. If you introduce a new fish from the store with a fungal infection into your tank, you risk spreading that fungus to any other fish in that tank that may have scratches or injuries too. Change your water immediately and monitor any fish that display white fluffy growths.

Most aquarium fish diseases can be controlled easily by keeping your water clean, which reduces the ammonia levels. Changing water regularly can also help to stop the spread of other diseases, although its important to be sure youre re-filling to the correct temperature to avoid stressing your fish, which lowers their immune resistance levels. Keep your tank maintained and youll be enjoying healthy fish for a long time to come.