I have one Alenquer, which I start to worry about and think about potential cross contamination issue.
Some time during a day it is dark an literally in next minute become light brown. I don’t see a pattern, but it changes colours quite often during the day. It’s maybe 50% dark and 50% light brown.
Eating as I would not give food for weeks. Fish might have a different perception, but I do 5 feeds per day, 90% daily water change + cleaning after feeding time.