By Land or by Sea?

Get off the range.

For many years, the evidence has been accumulating and now clearly shows that fats from land animals are bad for you.  Consumption of saturated fat and cholesterol lead to cardiovascular disease, heart disease, high blood pressure, strokes and raise the incidence of cancer.  In addition, these fats contribute to many other chronic degenerative diseases.  That is why I have made a concerted effort to eliminate these from my diet.  My goal is to not consume any saturated fat or cholesterol and this means eliminating all land based animals from my diet.  This include beef, pork, poultry.  It also includes dairy products: milk, cheese and eggs.
I should note that these land based animals are also significant contributors to agricultural pollution and global warming since they are very inefficient concentrators of protein and calories.  They waste 10 to 20 times as much nutrition as they produce.  It is much better for the environment and for your health to just say no to land based meat and dairy products.
Meat is a major source of protein and many people worry that if they don't eat meat, they won't get enough protein.  I cover this subject in detail here but suffice it to say that it's easy to get all of the protein you need from a vegan diet containing no meat of any kind.  However, many people would like to have some "meat" in their diet.

What about seafood?

There is, however, another broad category of "meat" we should consider and that is seafood.  This includes fish, shellfish, non-shell fish such as calamari, etc.  These have evolved with a different physiology and body chemistry.  Most significantly from the standpoint of nutrition they have evolved to store their energy in fats that have a much different structure than land animals which maintain their body temperature at 98F.  Because they live in water, their fats much be able to remain liquid at lower temperatures.  The saturated fat and cholesterol of land animals congeal at lower temperatures and it just wouldn't do for a fish to congeal.  Seafood tends to have different fats and these contain high concentrations of omega-3 fatty acids.  These fatty acids are originally created in plants (algae and plankton) and consumed by fish where they become concentrated.  They have been found to be protective of the heart and have anti-inflammatory properties as well as reducing the tendency of blood to clot.  Consumption of omega-3 fatty acids tends to lower your triglyceride levels. These are all good effects since they help your cardiovascular system stay healthy.  The anti-inflammatory effects help prevent arthritis.
The amount of healthy omega-3 fatty acids in seafood varies.  Salmon and tuna and sardines contain high amounts (about 3 grams per 100 gm serving) of omega-3.  Other seafood such as shrimp, cod and crab contain less.  Fresh water fish such as tilapia contain only small amounts (0.13 grams per serving) but are still healthy since they don't contain saturated fat and cholesterol.  It is interesting that flax seed also contains high amount of omega-3 fats.  Flax flour can be added to most cereals and baked good to improve nutrition.
You should also consider the environmental effects of the food you eat.  Land animal farming has many detrimental effects on the environment.  Some fish farming practices can also have detrimental effects.  Tilapia is usually raised in ponds which can easily become sources of pollution   Ocean farmed salmon can also concentrate pollution.  Wild salmon is better.  I usually avoid tilapia since it is low in omega-3 and can contribute to pollution.  The Monterey Bay Aquarium maintains a good list of which seafood is best to eat and which to avoid.  They consider environmental effects so there are differences in the source of the seafood and it is best to consult their guides which are tailored to the seafood found in different regions of the US.

Stick to the water!

Because of this, I include seafood in my diet. It is healthy!
Stay healthy!