How Do Fish Get Ich?


Ich, also known as White Spot is an incredibly common disease amongst aquarium fish. Ich is the shortened name of a protozoan, Ichthyophthirius, that uses fish as part of its reproductive cycle and is easily recognized both by the tell-tale 'white spots' on a fish, and the distressed behavior of affected fish, which often involved excessive 'flashing' (scraping themselves along the sides of the tank, against ornaments or against the gravel.)

If left untreated, Ich can become a serious problem in your tank, but with a little maintenance and TLC, Ich is fairly easy to cure. 

The first thing you must know about Ich is that it is likely present in every tank you buy fish from and every fish tank you admire. Healthy fish don't suffer from white spot all the time however, because healthy fish have a good strong slime coat that does not allow the protozoan to penetrate the skin of the fish.

You see, the white spots you see on a fish affected by Ich are places where the Ich protozoan has managed to penetrate the skin and start reproducing. Eventually, the white spots will burst open, releasing many thousands of new tomites (tomite is the name for the Ich protozoan at this stage of its life cycle) and each of those tomites goes on to find new fish to burrow into.

You can treat ich using several methods. A popular method is Methylene Blue, but it can stain the silicone of your tank (scratch that, it will stain the silicone of your tank) and it may put the fish under undue stress. I prefer to keep Methylene Blue usage to a minimum and instead concentrate on tank conditions and a natural, cheap remedy involving salt and increased temperature.

The first thing you must do when treating Ich is determine why your fish are stressed. Are the parameters of your tank water correct? (To find out how to determine if your fish tank water is safe for your fish to live in, click here.) If levels of ammonia, nitrite and nitrates are all good, then you may need to look to other causes. Are your fish overcrowded? Do they have enough hiding spaces? Is there too much aggression in the tank?

Before going for the methylene blue, I recommend doing a 20% water change, gradually raising the temperature in the tank to around 32 degrees Celsius (around 90 degrees Fahrenheit), and adding aquarium salt at a rate of 1 tsp per liter (2 tsp per gallon.) Some fish may not react well to salt, so add the salt gradually, and be prepared to do a water change if they react badly.

This is a natural, fairly gentle and usually effective way to treat Ich. The increased temperature (which should be done slowly, so as not to shock the fish) speeds up the life cycle of the protozoan, and the increased salt levels make it much harder for the protozoan to survive in the water column and outside the protection of the fishes skin.

After 3 to 4 days of this treatment, lower the temperature to normal levels slowly and do further water changes. It is always recommended that you do regular water changes in order to maintain water quality. Decrease the levels of salt in your tank to reasonable levels by changing the water without adding more salt. It is always a good idea to use aquarium salt, even in a freshwater tank. For advice on how to best use aquarium salt to prevent diseases like Ich reoccurring, click here.

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