How to Treat Columnaris in Fish in 10 steps

I didn’t mean to get an aquarium.

I met a neighbor who had some aquatic snails. We hit it off, bonding over her lovely garden and the weird way mystery snails glide across a tank. When she moved, she asked me to take a few, and I figured I could keep them alive and well in a vase on my dining room table. I was only supposed to get two… when my husband came home with 24!

So I purchased an aquarium. Fast forward a year later, and now I breed snails and have fish!

Fish are far more difficult to keep alive than any cat or dog I’ve ever had. It turns out that fish get sick when they’re stressed, and when I moved my school from one tank to another, a few of them started showing signs of columnaris.

Columnaris is a bacteria that lives inside of most tanks already and comes in several different strains. One of them acts so quickly that the fish die within 24 hours so there’s nothing to do. When fish get stressed, they become more susceptible to disease and may fall prey to the bacteria.

There’s really not a lot of information out there about how to treat this disease. After hours of research, here’s how I did it:

1. Make sure it’s actually columnaris. My local shops had NO idea how to diagnose this disease so, in this case, Google Images is your friend.

2. Move the impacted fish to a hospital tank. It helps if you have two filters running on your main tank so you can just switch one to your hospital tank and it’s pretty much instantly cycled. I didn’t have a spare filter so I had to buy one. Make sure you don’t get something with UV or carbon because that’ll decrease the efficacy of the medication you’ll be adding later. Also buy a thermometer and heater. I recommend using a 10 gallon tank as your hospital tank because most medications are A) expensive and B) meant to be added in 10 gallon increments.

3. Address the reason your fish were stressed in the first place and fix it. It’s no good if you save your fish from columnaris only to have them get sick again when they’re back in the community tank!

4. I purchased aquarium salt, API Fin & Body Cure, gel Terramycin, a siphon and two new buckets on Amazon.

5. Every evening I siphoned out 75% of the water into a “dirty hospital tank water” bucket. I filled another bucket with lukewarm water, added Prime and filled the tank. (Columnaris likes heat so it’s best to keep your tank as cool as your fish can safely handle.)

6. I added aquarium salt to the box’s directions and a packet of API Fin & Body Cure, also to the box’s directions.

7. I added some gel Terramycin to two clean Q-tips and placed them aside. I scooped out the infection fish with a net and placed it on a clean cutting board. (I’ll sanitize the net in between fish.) I swabbed the gel onto the fish’s wounds and carefully placed it back in the tank.

8. Made sure to give the fish the tastiest food possible. Anorexia is usually part of columnaris so try to entice your fish with their favorite meals!

9. Once the infection is gone, move your little ones back into the community tank and sanitize everything you used in the hospital tank. (For me, the infection cleared up in two weeks!)

10. Celebrate!


Photo Source: Abhishek R.