A 29 gallon is appropriate for 3 fish, modest feedings and routine water changes. If it is Marine Ich, the parasite will most likely always be present to some degree or another. Reduction of stressors is the key to preventing and dealing with Marine Ich. Do not over stock, stock slowly, one fish every 2-3 weeks. Monitor water quality, feed quality foods, avoid over stocking. A newly set up tank especially a nano is unstable. All parameters may be within normal range, but we can not nor do we test for all the dynamic factors that eventually provide a stable and hospitable environment for tank inhabitants. Basically go slow, let the tank age and buy the appropriate fish for the size of a tank. Looking forward to the images.