11. Shrimp

Are a dieter’s dream at only 84 calories per serving, with 0.3 g of omega-3s and a super-safe mercury level of 0.05 ppm. The drawback: A serving of shrimp has 166 mg of cholesterol (almost as much as an egg), so if you’re watching your cholesterol, don’t eat the pink critters more than once a week.

12. Catfish (if farmed)

Has 0.2 g of healthy fats, over 100 percent of your B12 RDA, and only 0.05 ppm of mercury. But the whiskered fish’s biggest claim to fame is 14.3 mcg of muscle- and bone-building vitamin D — almost three times your RDA.

13. Haddock

Gives up a good bit of omega-3s (0.2 g), 63 percent of your selenium, and over half of your B12 RDA. And barely-there mercury (0.03 ppm) makes it an anytime entr?

14. Tilapia

Is a freshwater dweller similar to catfish. Though it has only 0.1 g of omega-3s, tilapia is nearly free of mercury (0.01 ppm) and contains 84 percent of your daily selenium and 79 percent of your B12. So you can eat it till the sharks come home.

15. Lobster (the spiny kind)

Spiny lobster doesn’t have claws like the monsters from Maine, but its tail has tons more omega-3s (0.4 g vs. 0.07 g) and a lot less mercury (0.09 ppm vs. 0.3 ppm). Other highlights include 50 percent of your zinc RDA, 91 percent of your selenium, and nearly twice your RDA of B12.

16. Canned tuna (light).

It’s saddled with more mercury (0.12 ppm) than most fish on this list, but it has the least of all other types of tuna and still provides 0.2 g of omega-3s. Eat it no more than eight times a month and feel good about getting 75 percent of your niacin RDA and more than 100 percent of your selenium and B12.

17. Cod (from the Pacific)

Supplies almost twice the omega-3s of Atlantic cod (0.2 g vs. 0.1 g) and racks up 72 percent of your selenium for just 89 calories a serving. But don’t dine on it more than twice a week, because its mercury count is on the high side (0.1 ppm).

18. Halibut

Is a very good source of omega-3s (0.4 g) and provides more than 40 percent of your RDA of niacin, 72 percent of your selenium, and 58 percent of B12, so eating it every once in a while is a healthy option. Just keep it to no more than four meals per month because its 0.2-ppm mercury count is twice as high as cod’s.

19. Skipjack tuna

Is smaller than bluefin or yellowfin and therefore soaks up fewer toxins. It delivers an impressive 0.3 g of omega-3s, 72 percent of your selenium RDA, and 93 percent of B12. Still, it has 0.2 ppm of mercury, so limit it to four meals a month.

20. Orange roughy

Has two strikes against it: minimal omega-3s (0.02 g) and way more mercury (0.6 ppm) than any other fish listed here. But it’s low in calories and high in protein and selenium (75 mcg). So if you’re craving it, go ahead — just not more than once a month.