Looking for advice regarding this (presumed) illness that is gradually weakening and killing off my group of CW010 gold laser corydoras. They were wild caught I think. One by one the fish have been developing fluid filled cysts that appear between the scales. The whole fish can then start to get swollen and pale in colour with scales sticking out. Fish actively forage and behave fairly normally and the cysts wax and wane, but over time the worst affected ones have died off. I can see tiny white dots within some cysts. There was no sign of illness when I bought them. They live with some ottos and purple emperor tetras which seem to be fine. The tank is a 500L planted aquarium with a little CO2. Water is a mix of RO and tap to give tds around 140, pH 7, KH 5, GH 6, NO3 20, NO2 0, NH3 0. I attach some pictures. 
