Gentlemen, if you want to keep your sperm swimming -- and who doesn't? -- head on over to the nearest fish market and load up on tuna and salmon.

The fattier the fish, the better -- because the same fatty acids that make these fish such healthy choices for everything from your heart to your eyes to your brain are also positively critical to your fertility.

The omega-3 fatty acid docosahexaenoic acid (DHA) is one of the essential building blocks of sperm -- and a new study on mice shows how it's also a key part of the acrosome, which is what enables the sperm to penetrate the egg.

You might say it's the most important part of all. The mice would agree: When they were denied DHA, they produced fewer sperm -- and the ones they did create were misshapen, rendering them infertile.

But once DHA was put back into their diets, they began to produce again like, well, mice. (Side note: There has to be a pest-control angle in here somewhere).

This is, of course, just one study on mice. But human studies have also shown how high levels of these essential fatty acids can boost your fertility.

One study from just a couple of years back found that fertile men tended to have higher blood levels of omega-3 fatty acids, while infertile men had higher levels of omega-6 fatty acids.

And these days, with diets heavy in grain fed animals from factory farms, most of us get less of the desirable omega-3s and far more of the undesirable omega-6 fatty acids.

Call it one more reason to switch to fresh all-natural grass-fed meats.

Naturally, omega-3 fatty acids aren't the only answers for sperm health. A lot goes into male fertility -- and studies over the years have shown that high levels of vitamin D can boost the speed and forward motion of sperm, an essential trait called motility.

Other studies have also shown that junk food, soda and the BPA used to line canned goods (including soda cans) can slash sperm levels and turn the ones that are left into the microscopic equivalent of couch potatoes: slow, lazy and uninterested in the quest for the egg.

That would explain the recent rise in male infertility.