Not be the fly in the ointment, so to speak, but...

Fish oil is a good source of DHA and EPA which are essential omega 3 fatty acids. Omega 3s are known to stop and even reverse heart disease. They contain antioxidants, meaning they help prevent cancer. They also help keep triglycerides under control, helping to prevent diabetes. Because they work in cell membranes, they are excellent anti-inflammatory nutrients and work well on brain tissue. They are touted as having a positive effect on memory, so maybe it is possible that they would work on depression as well.

However...

The first problem fish oil capsules is mercury and pesticide contamination. There are mixed opinions on that. Some sources say they have tested fish oil capsules and found no contamination, while other sources say the contamination is actually higher in the oils than in the flesh of the fish they come from. Who knows. I'd rather not take the chance. The second problem is that the fish oil in most capsules is rancid. That's what causes the nasty fish oil burp. Fish oils become rancid very quickly and there can be a long period of time between when they are extracted and when they are encapsulated. The problem with rancid fish oils, besides the nasty taste, is that the omega 3s have been oxidized and are useless.

You can get a type of omega 3 in flax, hemp, or chia seeds. The seeds contain ALA, which can be metabolized into DHA and EPA, the useful omega 3s. The trouble is that your body's ability to metabolize ALA is very inefficient. Only about 5 to 7 percent of ALA is metabolized. You would have to eat several pounds of seeds to get the same benefit that you get from a few ounces of fish.

The best way to get the omega 3s is right from the source, fish. Nutritionists say you should eat a four oz. serving of oily fish (salmon, trout, tuna, etc.) 2 or 3 times a week. The best way to alleviate some of the contamination issue is to consume oily fish that are lower in the food chain, like sardines and anchovies. If you're like me, I'd rather eat mud than to eat a sardine. Herring is also a good oily fish at the low end of the food chain. If you decide to go with salmon or tuna for omega 3s, you want to get the fresh or frozen fish. Canned fish omega 3s have been oxidized.

Ok, pedantic rant complete.