Can The Size of a Fish Mother Determine the Size of Her Offspring?

What affects the size and health of fish babies? The size of a young fish may strongly influence its chance of survival after hatching, so it is important to understand why fish are born in the condition they are. One answer could be the age and size of the mother, but this has been hard to study in the wild. Sheepshead swordtail females carry their eggs until the baby fish are born swimming. Therefore, since most of the growing happens inside the mother, her offspring can only grow so big. This means that scientists can determine the condition of the babies by trapping the mother and measuring her age and size. Our research group used sheepshead swordtails to check if a mother’s age and size affects the size and health of her offspring. We found that larger, older swordtails produce larger offspring!