Marine Ich (ick) is one of the most common diseases found in the saltwater aquarium industry. Saltwater ick, or Cryptocaryon irritans, is a protozoan parasite that attaches itself to the gills and skin of the fish. Ich is present in almost all environments at all times in low levels. Healthy fish with good immune systems can effectively fight off the parasites with little to no visual detection. Ich is a stress induced disease. Once a fish gets stressed, the parasite then multiplies and takes over as the immune system of the stressed fish is not as strong to fight it off. Signs of ich can be many. The obvious sign is the white spots on the skin that look like salt grains. This is not to be confused with Amyloodinium, or Velvet, which looks like a fine white dusting on the fish. Other signs may include loss of appetite, flashing, lethargy, or breathing heavy.
As previously stated, Ich is a stressed induced disease. Any healthy fish with a solid immune system can fight off Ich without a full blown infection. The important thing in treating Ich is to find out what the stressor is. Stressors can be anything from aggression, temperature fluctuations, diet, lighting period, water quality and introduction of new fish.
Temperate stability in a saltwater tank is very important. There should never be more than a 2 degree fluctuation is a 24 hour period. Buy the best thermometer you can afford. A digital logging thermometer is best as this will help you determine the lowest and highest temperature. Many hobbyists fail in this part and buy the cheap glass thermometer and never know they have a problem.
Aggression is also at the top. When selecting fish you should always research compatibility. Knowing your fish are compatible and not trying to kill each other will have a long lasting effect on your tank. Lighting period in a tank should be pretty obvious. You would be surprised although how many people I have talked to that will have the lights cycle on and off 2 or 3 times a day. This is a big no no. Messing with the lunar cycle will defiantly stress your fish. 4-8 hours is ideal for any aquarium. Reef tanks have been proven to be just as healthy with 4 hours of light as 8 hours per day. Figure out the best time to have your lights on that works with your work schedule. Just make sure they go on and off only once per day.
Diet is a whole other topic. Here we are just going to make the statement that researching the diet of each fish is very beneficial. You may be able to keep a yellow tang alive on brine shrimp, but that does not mean it will be healthy and will have a good immune system. Water quality is another topic for another day, but again, optimal water conditions will do wonders at keeping a healthy tank. Also the addition of new fish can in a way be considered a stressor. Putting a new fish in the tank that already has an ich outbreak and is stressed out will allow ich to quickly reproduce in your tank. The rapid reproduction of ich can make the existing fish stress as they now have more ich to deal with and fight off.
There are many treatments out there for Saltwater Ich. However there are very few that are considered "reef" friendly and those are questionable. I would like to attack this from more of a holistic point. While copper, Maracyn, Ick Cure, and more have shown to be effective at treating Saltwater Ich, there are many side effects that extremely stress the fish more than the Ich itself. Since you can not dose these in a reef tank, you would have to catch the fish and setup a hospital tank to treat the fish in question. This alone can be very stressful. A lot of the strains of Ich today have become resistant to these medications as well.
So looking at this from a holistic point, the logical thing to focus on is the health and immune system of the fish. There are several things you can do once you notice there may be a problem. The key is to notice the problem early and act quickly instead of waiting until it is too late. Once a fish is completely covered in ich and not eating, the chances of saving it are slim to none with any treatment. Assuming the fish is still eating, the best thing to do is feed, feed, and feed. Six or seven feedings a day or more would be a common treatment. The idea is to keep the immune system as healthy as possible to fight off the infection. Now of course feeding that many times per day brings a whole new potential problem. Water quality still has to be erected high so this may also involve more water changes. Garlic has proven to be effective when soaked in the frozen food. Garlic is a natural appetite stimulant and makes the fish want to eat. I have also had luck adding garlic to the tank when a fish stops eating. Wait about 30 minutes and sometimes you can get them to eat.
During this time you need to focus on the potential stressor. If it is temperature, get it stable. It may involve adding a heater, putting a fan on the tank to cool it, raising the temperature, etc. Anything from 76 – 81 degrees is acceptable, but the key is stable. Is there another fish picking on other fish? If this is the case there may be no other choice but to remove one of the fish. What are you feeding the fish? This is very important. Tangs for example have ample food on the reef and constantly graze on algae. So it makes sense if you have a tang showing signs of ich to feed a lot of seaweed, spirulina, etc. Keep water quality at its highest. Protein skimmers are your best friends the in reef hobby. Not all protein skimmers are created equal. You get what you pay for on this piece of equipment so do not expect to spend $ 50 on a skimmer and have it perform as well as the $ 300 skimmer.
In summary, reef fish are a lot more elaborate then their freshwater cousins. Optimal conditions are required and will help prevent problems in the future.