Hi there and welcome to the forum. Let us know where you live, at least which country (medications, good stores. . . I assume you are in the UK). There are a few problems you will need to address. I am also new to fish. I have kept them about 4 years, and I have made every mistake there is to make. I have learned everything I know from this site.
First of all a 100 liter tank is about 26 US gallons, which is much too small for the fish you have. Clowns that are given a big enough tank so they are not stunted, will grown to 12-16" and are hefty fish. It is a myth that fish grow to the size of their tank. Small tanks create deformities.
I am not 100% sure what "2 black moor & 6 fancy fish" are, but if they are types of goldfish, they are incompatible with Clown loaches on many levels. Fancy goldfish like warmer water than regular goldfish, however, Clowns like 78-82 degrees, and if the water is cooler, then the CLowns will be stressed, and stress makes it easier for them to develop white spot.
Goldfish are massive waste producers, and it is very difficult to keep the water clean enough for clowns (not to mention the goldfish). The bigger the tank, the easier it is to keep the tank water clean. Your water should be Ammonia 0, Nitrite O and Nitrate less than 20.
Could you post your water parameters? Temperature, Ammonia, Nitrite, Nitrate, pH and Kb? I keep a journal and record all these measurements, including if I lose a fish and why.
Could you post what your substrate is (what kind of gravel or sand)?
What kind of decorations, hiding places, plants do you have?
Graying out is normal. They do it when they are fighting, which is normal. Clowns also need to be kept in groups of five or more to help them feel comfortable and to establish a hierarchy. Clowns are also nocturnal so it is normal for them to hide by day. When there are more, they feel more comfortable and come out more often. The goldfish, should act as dithers, but I like to use Rasboras, because they school, and the Clowns take a nice school of fish to mean that the coast is clear.
Please do not be discouraged. We have all made these mistakes. I had a baby bichir in a community tank. I was told she was a flake eater. In reality she is a fish eater, and it took me a while to figure out who was eating my fish. My solution? I got another tank.

Everytime I made a mistake, I got another tank. I have 9 permanent tanks, 1 Q-tank and a crawfish tank.
That would be my suggestion for you. Find a large, inexpensive, second tank, and set it up for your clowns. While you look for the new tank, put an extra filter on your current tank. That gets the filter seeded and cycled, so when you get the new tank, the filter will be ready to support your clowns in the new tank. Use pool filter sand as a substrate (Rinsed well). Add bogwood and caves for the clowns, and get a nice school of gentle fish, big enough so the clowns won't eat them. Otherwise I would return the clowns, because they will slowly die in such a small tank.
As I said, I am a beginnger and the experts may have better advice for you. But by answering my questions, they can better help you.