One aspect of selecting aquarium fish that doesn’t get talked about very much is fish lifespans. Fish lifespans differ dramatically by species, going from less than two years to over a quarter century.
Fish lifespans can affect aquarium owners financially (because of having to replace lost fish), but more importantly, because most aquarium enthusiasts get attached to their fish and want them to live as long as possible.
Kicking off our short lifespan list are Bettas, which only live about 2 years. Mollies, Swordtails, and Platys are also on the lower end of this list, because they generally live less than 5 years. From the saltwater fish, Gobies and Tangs live a pretty meager 2-4 years. Seahorses usually live about 3-4 years.
The winner when it comes to aquarium fish longevity is definitely the Goldfish. When properly cared for, Goldfish can live up to 25 years, though most die earlier due to environmental or care factors. Pacus live around 10 years, which is also a very long time. From the saltwater species, Lionfish, Clownfish, and eels can also reach 10 years of age.
It’s important to note that these lifespan numbers are more of a range than a definitive number, and that the quality of care can greatly affect whether a particular species lives under or over its average lifespan.