I have 4 clown loaches and they are completely covered in a very fine
powder. I have been treating them with white spot treatmenr for 2 weeks,
but the "white spots" remain untouched. I also increased the tempearture
to over 30 degrees Celsius. The clown loaches haven't lost any colour,
but they have become very shy, but do come out when it is darker. They
also scratch themselves on rocks.

In all the 15 years I have been keeping fish I have never seen such fine
microscopic spots. They seem to be less than 0.3 millimetre and they
never grow any larger except on the tail. They certainly never reach the
size shown in this photo below.

http://www.loaches.com/species_image..._ick_large.jpg

My large adult silver shark also has some of these spots, but the
density is far less, but the spot size is the same. In fact, they almost
look like microscopic bubbles trapped under its skin.

My mollies had a few on their tail, but they has cleared up.

The tank is 330 litres. I have been changing 20% of the tank water every
couple of days. The readings for nitrites and ammonia are close to 0,
but the nitrites did spike a few days ago.

Are these spots really Ichthyophthirius? They seem completely immune to
Protozin, which is the medicine I have been giving them. Usually, white
spot clears up in a few days and the spots are much larger and snowy
looking.

Any ideas welcome!

Nikki