NSW and Marine Ich

[Aloha Corals]

Aloha,

My questions stems from a debate about marine ich and never being able to keep it out of the display when using NSW.

Here in Hawaii (Oahu) we have two main sources we get our NSW from. One is Waikiki Aquarium and the other Anuenue Fisheries. Both of these sources are pumped up from a saltwater well into a storage tank where they are aerated. From there they are pumped as needed by the end user.

Will there always be a chance of marine ich using NSW?

AC-KEvin

[leebca]

The Marine Ich parasite, Cryptocaryon irritans, is an obligate parasite. That means it needs a host fish to survive. This parasite goes through different life stages. A couple of those stages are on or in the body of the fish. A couple+ of those stages are without a fish being present, or being 'off the fish.'

In the case of NSW as a source water the parasite could be in the water in any one of the stages of its life-cycle which are 'off the fish.' If that water is not treated (e.g., UV) to kill the parasite in the off the fish phase, then there is a chance that the NSW contains the parasite in one or more of its off the fish stages.

The question now is how long can the parasite live or 'hang around' without there being a fish. Dr. Burgess has found that some of these stages of the parasite can last up to 6 weeks without there being a host fish for the parasite to continue its cycle. It is for this reason that I recommend that a display tank remain fishless for no less than 8 weeks after the last fish was removed from it. At and after 8 weeks, the probability of there being any living parasite left in its off the fish stage is less than 0.001%. As you reduce the 'waiting time' the percentage probability goes up.

So NSW has the potential to contain Cryptocaryon irritans. The longer it sits, unused and away from fish, the probability of the parasite surviving goes down.

Many hobbyists use NSW here in Southern CA where I live. There are pros and cons to using it beyond fish diseases. You might want to read this post: WATER - Source and NSW

If the hobbyist wants to totally eliminate the possibility that NSW has this parasite in it that might infect captive marine fishes there are two approaches:
1. Let the water sit for 8 weeks. This might not work to well, depending upon the other (organic and inorganic) nutrients in the water. The water may 'grow' other bacteria. The bacteria can be filtered out, but then some of the benefits of using NSW would be removed (e.g., the micro elements).

2. Run the water slowly through a very intense UV sterilizer unit, or circulate it through such a unit. The flow rate, the length of the exposure, and the intensity of the exposure must guarantee that the parasite is rendered unable to infect fishes.

Now we come to 'the bottom line.' Just how risky is it to use NSW? We know the parasite doesn't like light. So water collected at the surface is less likely to have the parasite in it. However, water collected at the surface has a greater probability of containing human pollutants. Water collected near a reef, in deeper waters, or where a large population of fishes are, has a higher probability of containing the parasite. So what is the bottom line? The bottom line is the use of NSW is not risky at all. However, there is always that very small chance. . .

Thanks for asking!