That's a lot of fish for a 29 gallon. How often do you water change? I recommend 25% weekly. A bigger tank if possible. If it's ick you'll have to treat the whole tank. Raise the temp to 80-82 degrees and add aquarium salt. Since you have catfish, use half of what the box says. Do daily water changes for one week, then wait a few days, repeat process. Ick is caused by poor water quality. Probably from being overstocked in this case.