A  fish study commissioned in 2007 by Friends of the LA River (FoLAR) collected fish samples at four sites in the Glendale Narrows and found results similar to a 1993 NHM study. During two different samplings, the biologists caught 1214 individual fish: 668 mosquitofish, 271 tilapia, 92 green sunfish, 83 fathead minnow, 58 carp, 24 black bullhead, seven Amazon sailfin catfish and one largemouth bass.

Testing for toxicity to assess the health risks associated with eating  fish caught in the LA River, the FoLAR report found relatively low levels of polychlorinated biphenyls (PCBs) and mercury. PCBs were highest in carp – 9.4 to 16.3 parts per billion – which is below the 21 parts per billion that the California Office of Environmental Health Hazard Assessment (OEHHA) deems safe for folks eating fish three times a week. Mercury was highest in sunfish– 20 to 50 parts per billion, again below the OEHHA advisory level of 70 parts per billion for folks eating fish three times a week. Higher levels are likely to accumulate in older larger fish.

The study recognized that its sample may not be sufficient to be conclusive, as most of the carp analyzed were neither large enough or mature enough  to have accumulated significant toxins).  Since most of the water in the LA River  comes from sewage treatment plants, FoLAR was surprised that the toxicity levels were not higher.  Nevertheless, use caution before eating what you catch, particularly if you are doing it on a regular basis.

Before eating any fish caught along the lower LA River and Long Beach Harbor, check current Department of Fish and Game warnings. Agencies caution against eating several species found in that area, including croakers and queenfish.

Grilling or broiling the fish as fillets is thought to be safer than using them whole in stews or soups, since chemicals can concentrate in the head and insides.