Many people eat more fish during Lent.

There is a lot of controversy on the health benefits of eating fish. At one time, fish was one of the healthiest things you could add to your diet. This is also true today, but in far less quantity and depending on what type of fish you eat.

The many toxins found in fish include Mercury and PCB’s. Fetuses, infants, and young children are at greatest risk of harm from mercury, which can damage developing brains and nervous systems.

Because mercury is stored in our bodies, just as it is in those of fish, women planning to have children should also avoid high-mercury fish well before they become pregnant.

Adults can suffer harm, as well: In April 2003, Environmental Health Perspectives reported that 89 percent of study subjects — chosen if they ate a significant amount of fish or showed symptoms consistent with mercury poisoning, such as fatigue, headache, decreased memory, and joint pain — had blood mercury levels above the EPA’s safety threshold of 5 micrograms per liter.

Young children, pregnant women, nursing mothers, and women of childbearing age not eat more than two or three meals, or 12 ounces total, of fish or shellfish a week. They should limit high-mercury fish to one serving per week. To be safest, however, The Green Guide and the Environmental Working Group recommend limiting moderate-mercury fish to one meal a month, and bypassing high-mercury fish completely. In addition, their list of high-mercury fish is longer than the FDA’s, which includes only king mackerel, shark, swordfish, and tilefish.

Polychlorinated biphenyls (PCBs) — neurotoxic, hormone-disrupting chemicals banned in the U.S. since 1977 — were found at levels seven times higher in farmed salmon than in wild ones. PCBs are persistent organic pollutants (POPs), which accumulate in animal fats.

Because most farmed salmon are raised on feed that includes ground-up fish — and sometimes other animals, such as cattle — their bodies collect POPs.

PCBs are also found at high levels in fish from polluted water bodies, varying from locale to locale; state health advisories list which fish should not be consumed by children, pregnant or nursing women, and women of childbearing age.

Wondering what fish to eat? Following is a list of fish to avoid and ones that are safe to eat in moderation.

Fish to avoid, high mercury: Atlantic halibut, king mackerel, oysters (Gulf Coast), pike, sea bass, shark, swordfish, tilefish (golden snapper), tuna (steaks and canned albacore). High POPs: Farmed salmon. Limit to once a month if pregnant/nursing.

Fish to eat: Moderate mercury: Alaskan halibut, black cod, blue (Gulf Coast) crab, cod, dungeness crab, Eastern oysters, mahimahi, blue mussels, pollack, tuna (canned light). Children and pregnant or nursing women are advised to eat no more than one from this list, once a month.

Low mercury: Anchovies, Arctic char, crawfish, Pacific flounder, herring, king crab, sanddabs, scallops, Pacific sole; tilapia, wild Alaska and Pacific salmon; farmed catfish, clams, striped bass, and sturgeon. Children and pregnant or nursing women can safely eat two to three times a week.

Low POPs: Wild Alaska and California salmon fresh or canned.

Limit fish consumption by category, not individual species. For example, both cod and mahimahi are moderate-mercury fish, and only one from this category should be eaten per month — not one meal of cod and one of mahimahi. If you’re in a high-risk group, don’t eat the skin and fatty parts of fish, where POPs collect.

Eat grilled, baked, and broiled rather than fried fish, to avoid fat.