White dots on my guppies

Hi I have seen lately white dots on my guppies. It started several days a go on one of them, and now three already have them.

Any idea what's that?

Help would be greatly appreciated.

It is more than likely ich.

It does sound like ich, which is an external parasite. Fish usually get ich because their immune system has been weakened by poor water conditions or by moving from one aquarium to another. Before adding medications please read some of our blogs about the nitrogen cycle, the drip acclimation technique, etc.

Sometime white ich (not sure this is the exact term in English - feel free to correct me) can be caused by too low temperature.
On such cases you might want to raise the temp to 28C-29C.
It should be gone in several days.

BTW, it might also be related to PH

The wrong temperature will certainly compromise a fish's immune system and leave them vulnerable to diseases and parasites.