Answer to Question #277095 in Genetics for nash

Question

When a dark blue fish and a light blue fish with dark blue fins were mated , all offspring became dark blue. What could also be seen was that part of the offspring got light gray fins.

Explain with the help of genetics why all fish turn dark blue.

Use relevant terms in your explanation and also show using intersection diagrams.

Now we look at the fins instead. How come some of the offspring get gray fins instead of dark blue like the parents?

Answer 1

Most common reason for a betta changing colour is stress, but indeed can also be caused by illness. If your fish changes colour regularly, and is otherwise healthy and acting normal, I think stress will be the reason. I've had a female betta in the past, and I would notice the same every time I did my tank maintenance.