Yesterday I noticed a small hole in the middle of the tail fin of my Dwarf Flame Gourami. He otherwise appears to be in top condition and all of his tank mates, 9 neons, 3 ottos and 3 Rosy Tetra's that all are doing fine. Water conditions are good to, 0, 0, 10, PH is about 7.5. I do water changes weekly on this 29 gallon tank. Any suggestions?