In recent days, the ranchu pond has been warming constantly and gradually and is now sitting at around 13.5 degrees C. The weather here has been mild for several days, but we have freezing temperatures forecast over the coming days, although this shouldn't now be an issue. I have introduced a small amount of food and they have all fed eagerly and passed waste, which is a good sign. I have carried out a couple of partial water changes, so as not to shock them. Along with the temperature rises and the food, the ranchu have perked up considerably, moving freely, almost at full speed.
It appears that my warming was probably well timed, as one of the females was beginning to develop an ulcer of some sort on her wen. Fortunately, this appears to be disappearing with the cleaner water being introduced. The females bellies also appear to be fattening up nicely, which i hope is a good sign of egg development. Within the next few days i expect to bring together the males and females and carry out a full 100% water change.
I am lucky to have found and follow with great interest, the diaries of many Japanese ranchu breeders. It's been reassuring to read that my current methods are similar to many, with many ranchu breeders in Japan enduring similar weather conditions as we have had here in the UK. Japanese ranchu pond temperatures currently appear to be anywhere from 10 degrees C, to 16 degrees C already, with spawning anticipated before the end of February at the higher temperatures.