What is the lifespan of a common fish?

You're asking a tricky question! "Common fish" is too broad a term. There are thousands of fish species, each with its own unique lifespan.

To give you a better idea, here are some examples:

Short-lived:

* Guppies: 2-5 years

* Goldfish: 10-15 years (though they can live much longer in ideal conditions)

* Zebrafish: 3-5 years

Medium-lived:

* Koi: 25-50 years

* Rainbow Trout: 5-10 years in the wild, longer in captivity

Long-lived:

* Eel: Up to 100 years

* Greenland Shark: Over 400 years (possibly the longest lifespan of any vertebrate)

* Ocean Sunfish: 10-20 years, but some evidence suggests they might live longer

Things that affect lifespan:

* Species: Different fish have different natural lifespans.

* Environment: Water quality, food availability, predation, and stress can all affect how long a fish lives.

* Captivity: Fish in aquariums often live longer than those in the wild because they have less stress and better care.

So, there's no single answer to your question!

To find out more about the lifespan of a specific fish, you can search online or consult a fishkeeping guide.