If you’re trying to become a father, you may want to load up on omega-3s — new research indicates the fatty acid found in fish is crucial in transforming dysfunctional round-headed sperm into the strong, cone-headed swimmers necessary for fertilization.

Docosahexnoic acid, or DHA, is an important omega-3 fatty acid involved in eye and brain development, and recent studies in mice have shown it may have an impact on male fertility as well.

Researcher Manabu Nakamura of the University of Illinois at Urbana-Champaign said, “DHA is high in the testes and brain, but until this it was not well understood what it does in these tissues … About three years ago we created the knockout mouse, which isn’t able to make its own DHA, and we learned that DHA is really essential for sperm formation.”

In previous work, Nakamura and his colleagues studied mice without a DHA-synthesizing enzyme, finding that if these mice also didn’t get DHA in their diet, the males were infertile — and when their diets were supplemented with the fatty acid, fertility returned.

In the new study, published in the issue of the journal Biology of Reproduction, the team looked at how sperm develops in DHA-deficient mice, determining that DHA plays a role in the formation of a structure called the acrosome on the head of the sperm. The acrosome is a pointy caplike structure containing enzymes that break through the egg’s outer layers, enabling the sperm to fertilize it.

DHA deficiency isn’t very common since humans and other mammals are able to make their own DHA from other fatty acids, but if that DHA-synthesizing enzyme is defective, it could result in fertility problems.

“Some [people] may have a decreased ability to synthesize DHA,” said Nakamura. “In [that] case the dietary supplements may help.”