Blind Cave Fish can tell time

The blind cave fish has spent millions of years underground isolated from evidence of day and night still  has a working biological clock. For normal animals the internal clock is called circudian rythm. For example Animals that can see know what time it is if it is dark or sunny outside. Yet for the cave fish their is no answer to now it has a clock. The only thing that scientists found was that they might know what time it is when they get hungry. For example they have a certain time for each meal. What shocked the scientists the most was that the cave fish was not sincronized in a 24 hour clock but in a 47 hour clock. According to the scientists in the future the cave fish might loose its ability to tell time.