Fish rubbing gravel

Question
Hi Jon,
New fresh water fish hobbyist, 2 months. Have 26 gal tank with real plants
, 2. Male guppies and 4 male plates, 2 male swordfish and 2 coo cats.  
One of the cats got ich, began treatment 5 days ago with quick cure. Did
15 percent water change yesterday. Did one.2 days also also.  Added final
treatment this morning, seems cat is cured but one day additional
treatment to make sure.  Noticed one of the swordfish rubbing on the
gravel today?  Planing on another water change tomorrow am and
reinstalling carbon filters.  Been using only sponge filters during treatment.
Heard rubbing is a toxic response, should I do any additional water
changes? Or what do you suggest?  All other fish seem ok, but did do a
previous water change when one of the guppies seemed to be acting
funny.  Like I said today's treatment will be the last.
Thanks,
Tom

Answer
Tom. Being that you mentioned the fish have ich, many times fish scrape against an object when they have an external fungus, parasite or ich. It sounds as if you treated the problem well even performed water changes, that was great. One thing I have to ask is what type of medication you used. I use and always will recommend Maracyn brand medication. You don't even need to remove carbon from the filtration devices with this med. Normally when there is a toxin or the water chemistry is off or unsafe, the fish will seem to shake, noticeably now and again. If you monitor the water quality and it is safe, wait and see if you notice any other signs of a disease or fungus. From there, as I mentioned, use maracyn meds. Hope it goes well. If you have any other issues or concerns, feel free to share or ask. Good luck.