Fishkeeping: How To Treat Ick

What is 'ick' and how do I treat it?

Ick is a parasite that bores into the body of the fish, and then releases its young or its eggs. It goes through this vicious cycle for about 18 days. It can be deadly, but also at the same time, it can be curable. A lot depends on how quickly you catch it. It literally looks like salt sprinkled on your fish; normally on its head, or its tails. It's typically caused by water temperature fluctuation, but occasionally also the water chemistry affects it. However, if water temperature fluctuation varies by greater than a degree, this has the potential to bring on ick a lot of times. The best way to cure it is to use a copper-based product in a fresh water system, or a system that doesn't have any invertebrates. Copper kills invertebrates, because ick's an invertebrate that's in fresh water. In salt water, you can use copper. We also like to drive the specific gravity down because inverts need a higher-specific gravity than fish. Fish can tolerate really low salinity levels, but inverts cannot. They also don't like high temperatures, but depending on how sensitive the fish is, how many fish have it, how valuable they are to you either personally or monetary, we'll use a combination of all those weapons in saltwater and even sometimes in fresh water, the temperature and the specific gravity, salt water only, and use of copper.