At the begining I will describe the concept of western aquarists – more popular one. You can read about it on Alan. S. Bias swordtail guppies blogspot.
It is autosomal dominant gene. In heterozygotous form asian blau impairs production of red color in erytrophores causing reduction or total absence of red color on a fish and fins – this is it’s main function. To a much less degree it also lower yellow color pigmnets production. In general because of reduction of red color phenotype is yellow/irydophore based – usually very shiny effect can be obtained. I also read that the longer you keep the line without outcrosess the more it starts to reduce yellow color as well. In homozygotous form it completly removes red and yellow pigment. Some of black melanophores also appear to be removed. Also guanophores are affected. Because of so strong reduction of pigment cells tail fin shape is also affected – fin development is greatly reduced. Those are the basics of asian blau gene without going too much into details. For me there is one problem with this theory. There are few genes that work very similar to asian blau – they also mainly affect red color production: european blau, hellblau and ivory. Every one of them works slightly different to others. Making things little bit complicated in my opinion.
Russian breeders has different approach to subject of so called anerythristic (lacking red color) fish. According to them there is one gene causing reduction or total absence of red color. Belonging to base body colors make it an reccessive autosomal. Genotype which includes only it in homozygotous form will be: MMGGeeXX – total abcence of red color. Differences in phenotype comes from two reasons. Gene is in heterozygotous form: Ee, second reason is the nature of red color in guppies. Easiest to describe it with an example of full red fish. This kind of guppies were selected over the years by selection of fish with partial red cover, with red dots and so on. For further breedings only the most red fish were choosen. This way more and more red fish were created. Naturally because of many different genes involved in creation of red pigment – gene reducing red pigment also will work differently.