Let's talk LIFESPAN


Staff member
RC Mod
Do fish die---naturally---often? Do they have short lives?
Once they survive being hatch---those that make it to adulthood can live a decade or more---record for a koi is 235 years.
For most that we keep, 10 years.
For a clam---hundreds of years.
For a coral---virtually immortal, in terms of breaking off and both bits growing. That frag you just bought has an ancestry maybe going back hundreds of centuries. If not hundreds of thousands of years.
I have a crab I know has been with me over 10 years. Little scarlet microhermit.

An 'experiment' with live fish and critters is not your only option.
TESTS of water quality will see your specimens live longer and grow well. Test weekly. A key one-and-done test for most weeks is Alkalinity. If that's ok, calcium and magnesium will be. If you have to restore balance, however, bring magnesium to 1300, THEN your alkalinity to 8.3, then your calcium to 420. These readings work well for stony coral and about anything else.

Read the thread "Cycling isn' t the End of It" up above for more help. ^^^ It can save critters, and save you a lot of money and grief.


Premium Member
To add to your post, average Tangs in the wild live 35-40 years. Record for a wild female clown is 28 years.

Food for thought, Charles Delbeck related in this paper on marine fish longevity a researcher working with Asterropteryx semipunctata, aka Starry Goby, wild specimens had a maximum life expectancy of ~16 months but a mated pair were maintained in a laboratory aquarium for over 11 years.

As far as corals the the picture is a lot more complex. A coral genotype might have a life expectancy of millenia but colonies may have life exepctancies of just decades or even just a few years. Fungia spp. polyps may have life expectancies of only 30 years while other speciess polyps may show signs of senescence after just a few months. (See also this paper and this paper)


I know that Echinoderms (i.e.- Sea Urchins and Starfish) can live a long, LONG time, too - sometimes for DECADES in captivity as well as the wild.
My one sea urchin takes a licking but keeps on ticking. Wanted to add another one, but he died in transit due to Fed EX being LATE!! :(
I always thought that in a WELL MAINTAINED aquarium with good parameters and a proper quarantine setup, many fish can outlive those in the wild sea (because many get eaten, get sick, etc.) but maybe I'm wrong.


Premium Member
My suspecion is many echnoderms should live decades also. I've had several green brittle stars live past 2 decades and judging from the growth rate I've seen it may take a decade to reach adult size. It's hard to say with urchins because there's the unkown of how much they need to eat daily but I have a Diadem specimen in one of my systems that's now been in the system at least 14 years and was an adult when added. I've had several dwarf angels live past the 11 year mark which from what I've read is the max age for a wild dwarf angel and a fair amount have died around the 10 year mark.