sick red eyed tetra

Question
I have two red eyed tetras that are swimming primarily with their tale lower than their body. One is hiding frequently and the other has a small white dot just below his caudal fin. I recently lost a neon with the same spot in the same place. There is only one tiny spot the size of a period.
I have a 29 gal community tank with 13 fish. I change about 30% of the water once a month.

Answer
Hi Janey:  I would add aquarium salt if you do not do so already.  Try to feed them some brine shrimp as it sounds like they may have a swim bladder issue and the brine will help if its related to an intestinal blockage.  If there is no improvement by tomorrow or so I would start them on a regiment of General Cure... Keep me posted... dave