Not Medical Advice: Yes. As tuna is a low-fiber food. However, you should take it in moderation.
Check this low-fiber diet for colonoscopy preparation shared by Ghc.org.
Start preparing three days before your colonoscopy. For example, if your colonoscopy is scheduled for Wednesday, you would start the low-fiber diet Sunday morning.
Here's what you need to do to prepare for your colonoscopy:
Three days before your colonoscopy, eat only low-fiber foods. Also, stop taking any fiber supplements or anti-diarrheal medication.
Two days before, continue eating only low-fiber foods.
One day before, go on a clear-liquid diet.
The evening before, drink half of a prescription laxative drink to clean out your colon for the procedure. (You'll finish it the next morning.)
Colonoscopy is quite safe but not many people are comfortable with the idea of being análly probed. Check out some tips on how to make things a lot easier for you at Newhealthadvisor.com.