I have never heard of any special word for a mature female Betta s.
Who cares about whales they are basters
A mature female turkey is called a hen.
Mature female pigs are called sows.
A mature female goose is called either a hen or a goose. A mature male is called a gander.
A mature female horse is called a mare.A mare.
One way to sex a tropical fish is to observe a mature male or female. The female will eventually lay eggs and the male will show his penis if a mature female is around.The way to sex a tropical oscar fish is to simply observe whether or not the female lays eggs. It is not possible to tell by just looking at the fish.
Hen
Sow
A female duck is called a duck or a hen as a male is called a drake
A mature female horse is called a Mare.
A mature male pig is called a boar. A mature female pig (that has produced offspring) is called a sow.
The mature male has brighter colours and larger flowing fins than the female.
Gymnosperm is the sticky liquid formed by a mature female cone.