Fish has Omega 3 fatty acids, one of the finest and immensely beneficial dietary fatty acids known on this planet. Whereas other fatty acids can increase cholesterol and encourage fat built-up inside the body, fish oils are a wonderful exception. They have anti-oxidant, anti-inflammatory and anti-aging properties that can help you live younger, healthier and shining for longer.
The basic aging process starts with free radicals damaging the body cells and altering their configurations. Free radicals are bye-products of oxidation processes associated with metabolism and they're completely unavoidable. The only way to escape their wrath is to fortify the body with powerful anti-oxidants. That's what you get from fish oils. Omega 3 fatty acids that are abundant in fish oils are extremely powerful anti-oxidants that can stop the decay of cells and retard the process of aging at the cellular level.
If it is good for us folks it must be terrific for fish.
http://www.senescence.info/nature.html
An article on the aging process from a genetic viewpoint.
A quote from the artice will suffice.
“Teleosts such as rockfishes also live very long, show no signs of reproductive senescence and grow continuously, albeit slowly (Fig. 3A). Some rockfishes, such as Sebastes aleutianus have been estimated to live over 200 years and show no signs of aging (Cailliet et al., 2001).”
There is, of course, more if one cares to research the phenomenon.