Ich is probably the most common parasite or ailment to affect aquarium fish. Good news is, it’s completely treatable! Through my years working in fish stores and owning an aquarium maintenance business, I have dealt with it more times than I can count.

Here are my three steps to treating ich.

Know your enemy. Ich has a unique life cycle, and you need to understand it to effectively medicate.
Treatment. Learn about the 4 best active ingredients to treat ich and how to dose them.
Prevention. The best way to deal with ich, is to prevent it.

Check out the video! ⬆️

Step 1 - Know your enemy

What is ich?

Ich AKA Ichthyophthirius multifiliis is a protozoan parasite. Sounds fancy, but basically what that means it’s a single celled parasite. Technically, a tissue sample and microscope are required to identify ich with absolute certainty. However, if you’re noticing one to a bunch of fine white dots, almost like a powder sugar coating on your fish, then you can be pretty sure it’s ich.

Ich burrows itself just under the outer most layer of a fish. This layer of skin cells and mucus membrane is incredibly thin, which is why we’re able to see them on our fish, where it feeds off of the fish it’s become embedded in. Pretty grotesque eh? It’s highly contagious, and to make things worse, it can’t be treated with medication while embedded into the fish because the fish’s mucus and epithelial cells protect it.

In order to treat it, we need to catch it at the right point in time, and we need to know about ich’s life cycle in order to do that.

Example of fish with ich, a Venezualan hi fin.

Ich life cycle

What’s a life cycle? Well unlike humans who are born small and essentially grow into bigger versions of their infant selves, some animals have different stages in their life cycle. Like how butterflies start off as caterpillars and molt.

For ich, there are three life cycle stages. The first one is what I already talked about, the feeding trophont.

When the trophont becomes a mature adult it leaves the host body, our fish. At this stage its referred to as a tomont. It forms a cyst with a sticky outside that’s able to latch onto its surroundings and form a protective barrier; this stage is sometimes called a tomite. During this stage ich divides like CRAZY. One ich cell can divide into hundreds, even a thousand different individuals. And they’re not sexually reproducing organisms, which means that one ich cell left unchecked, can wreak havoc. In the cyst stage, they are also protected from medication.

The last stage is when ich is released from the cyst into the water column. They are referred to as theronts at this stage. This is when they basically cruise around looking to infect a host to restart the cycle. This is when they are susceptible to medications.

The life cycle of ich depends on water temperature. In warmer water ~ 80℉ / 26℃ they can complete their life cycle in 3-6 days. In cooler water, maybe 70℉ / 21℃ and under it can take a few weeks.

Ich life cycle.

How bad is ich for our fish?

When I read about ich, I always hear it being described as pretty much the worst thing that can make its way into a tank. While that can be true, it’s not always the case. These little Venezualan hi fin cories (picture above) seem to be very susceptible to catching ich. Both times I’ve moved them into different aquariums, they’ve caught it. Fortunately, both times they’ve had ich, it didn’t spread to other fishes. Same with this time around. I used a medication called kick-ich which didn’t seem to help. After a few weeks of that, my cories seem to be behaving fine, and it hasn’t spread to my other fish.

I’ve also seen ich absolutely destroy tanks. Thinking back to the years I worked in fish stores, ich has serious potential to kill susceptible fishes. When enough of the parasites invade a fish’s gills, it makes respiration impossible which is why they often look like they’re breathing heavy. They overburden a fish by consuming them basically. Young or stressed fish are extremely susceptible to ich.

Do not be fooled by me or other people telling you that ich wasn’t a problem in their tank. It has the potential to wipe out your entire tank, so take the steps to stop it before it spreads like wildfire.

Step 2 - Treating ich

There’s a few different medications that you can use to treat ich. Catch is, you can only treat it when it’s in that third life cycle stage. The four biggest active ingredients used to treat ich are copper sulfate, formalin, malachite green and methylene blue. You can find a number of medications for each active ingredient, but my personal favorite’s are methylene blue and malachite green. I would stay away from medications that don’t use one of these three ingredients. There are a lot of natural tinctures and potions that are supposed to help with various fish meds, but I think you’ll be tossing your money down the drain with those.

Before picking a med, make sure that all your livestock are compatible with it. For example, shrimp and other invertebrates do not respond well to copper!

The biggest thing to think about when treating, is that you need to hit ich during that third life cycle stage. So even if you aren’t seeing any on your fish, it could be that they are in that protective cyst stage and about to be released into the water column. Make sure to dose medications for at least a few days after not seeing any signs of it. If you keep your water cool because of the species in your tank, you’ll need to potentially dose for up to 3 weeks after not seeing signs.

What I’m doing for treatment with my Venezuelan hi fins is bumping my temp up to 82℉ to speed up the life cycle of ich and increase my fishes metabolism resulting in a stronger immune system. It’s important to speed up the life cycle of ich, if your fish can tolerate the high temps, because it reduces the amount of times that we need to medicate our tanks. Some meds like this require frequent daily water changes which is also stressful on fish. So best to deal with this as quick as possible.

All I’m doing is dropping in the recommended dose for my tank in a high current area. Then I’m waiting 24 hours and doing a 30% water change. I’ll do this everyday until I haven’t seen any signs of ich for three or four days. While doing the water changes, it’s a good idea to suck up as much gunk and debris from the bottom of your tank, because that’ll likely pick up a good number of ich cysts.

Step 3 - Prevention

Last but not least, what makes our fish susceptible to catching ich? How can we minimize the chances of bringing it home to our lovely display tanks?

Well, the first thing you can do is quarantine your fish. Generally speaking a one month quarantine is enough to almost completely eliminate the chances of any diseases from entering your tank.

The other thing is just general animal husbandry. Take care of your pets. Don’t let the water parameters get out of control. If you tend to get nitrate accumulation in your tank, do water changes.

Maintain a stable temperature. In the wild, fish are most likely to catch ich during transitional seasons like fall and spring when temperatures are shifting quickly. The same thing can happen in your aquarium, so try to maintain a stable temperature by using a heater and being diligent during water changes.

Ensure that your fish are getting a good diet. What and how often you feed your fish will depend on the species, but make sure to give them a varied diet. Also make sure that all your fish are eating, including the smaller and shyer ones.

Having rough tank mates can cause stress for more timid fish, making them more susceptible to ich. Even something as simple as having too much current can stress out your fish making them more susceptible.

If you live in Norther Colorado and are having a hard time tackling ich, feel free to reach out and schedule a consultation! If you don’t like in the area, we also offer remote consultations.

OK, that’s all I got for ich. Hopefully you’re feeling confident enough to rid your tank of ich. If you have any questions, please let me know in the comments. 💬

3 easy steps to rid your fish tank of ich