Hello!

Are the roots of my fairy castle cactus rotting? :/ I noticed this while replanting. Thanks!

Nope, not that I can see, rot would be wet and squishy, this appears quite dry. Definitely could use a bigger pot.

Just transplanted it! (: None of my other cacti roots look like that, very interesting!

Yep, those are normal looking roots. Yep, it could use a bigger pot.

Agree with mcvansoest & Daisy. Those are root hairs. Very normal. Does look like fungus and I can see why you could be upset.

How do you fix root rot on a fairy castle cactus? I hope i can save it my son gave it to me years ago and everytime he see's it he gets all happy and proud. My son has special needs.

Not the best one to help others since I got troubles myself. With all the rain we had in the north east, I experienced some rotting myself. My best advise is to try to keep them dry and I use lots of grit in my planting mix. I don't have access to pumice but I use a lot of crushed granite which goes by the name of poultry grit. It keeps the roots much dryer and free draining. If your soil is wet now, remove the plant and place on newspapers to dry out the roots and replant in gritty mix. Keep dry and out of sun until it can regrow it's roots.

I'm afraid your Fairy Castle cactus may not recover. I suspect you kept it too wet and in too big a pot.

Take cuttings from the top good section of your cactus and put in a pure grit mix with just a very little spray mist every week until you suspect rooting. No watering until it develops roots or else it will continue to rot.

Hello rage1872, ideally, I would change the media you have now and add more pumice to it as Stush mentioned. Carefully unpot and see the condition of the roots and parts below soil line, if it shows squishy below soil line, you may have to cut them off and allow that part to callus. You can dab some cinnamon as fungicide, set it aside. The same on the top part, I see on the photo, on the left side, there is a very yellowed branch, and you can see the portion connected to the main plant already has a somewhat callused part, you cut from that callused part to remove the already yellow branch.

After it has callused, you can repot in new gritty soil mix in a smaller container with drain holes for now. Position in bright, dry and warm area, to allow new roots to form. It may take some time, and it really depends too how far along any prior internal damage has run. But don't lose hope, at times it does require a lot of patience and discipline not to water yet, to assure chances of survival for it.