Before you rush out and buy 700 two-inch fish (5 centimeter) to populate your one-hundred-gallon (378.5 liter) aquarium be aware of one shortfall to small fish, they don’t live long. Most two-inch fish only live two to five years.
Live bearers typically live shorter lives than egg layers. So, an aquarium full of guppies is tempting but they might only live two years. Note that in my experience with male fantail guppies, you’re lucky to keep them alive for a few months.
On the opposite side we have a friend with a discus he swears is 25 years old. It’s a factor to consider.
This is a list of tropical fish lifespans:
- American Cichlid, moderate, 8 years
- *American Cichlid, large, 15 years
- Angelfish, 12 years
- Apistogramma, 2 to 3 years
- Aulonocara, 8 years
- Barbs, small, 5 years
- Barbs, medium. 8 years
- *Barbs, large, 10 years
- Betta, 3 years
- Chinese Algae Eater, 15 years
- *Clown Loach, 15 years
- Congo Tetra, 6 years
- Corydora, 5 years
- Danio, small, 3 years
- Danio, large, 5 years
- Discus, 15 years
- Glass Catfish, 7 years
- Goldfish, common and comet, 15 years
- Goldfish, fancy, 7 years
- Gouramis, 4 years
- Guppy, 1 to 2 years
- Haplichromes, 10 years
- Hatchetfish, 2 years
- Killifish, 1 to 2 years
- Mbuna, 8 years
- Mollie, 4 years
- *Oscar, 15 years
- Otocinclus, 5 years
- *Pacu, 10 years
- Platy, 3 years
- *Pleco, 20 years
- Rams, 2 to 3 years
- Rainbowfish, 8 years
- Rasboras, small, 5 years
- Rasboras, medium, 8 years
- Silver Dollars, 10 years
- Swordtails, 3 years
- Tetras, Small, 5 years
- Tetras, Medium, 8 years
- White Cloud Mountain Minnow, 7 years
*Fish which get over eight inches (20 centimeter) in length.
Obviously if a fish such as a betta is only sold once it has been become full grown and well colored this can take a year or so off the age the home aquarist sees. Also note that some fish typically continue to grow throughout their lives, so some of these long-lived fishes like clown loaches and plecos can get very big.
Note that “fancy” fish with compressed fat bodies such as butterfly goldfish, bettas, or some types of livebearers such as balloon mollies are genetic dwarfs. Their bones don’t develop the length that they should have, and the internal organs are compressed. Dwarfism is a known harbinger of kidney disease, distorted swim bladders and other problems with internal organs.
Dwarfs also tend to have compromised immune systems for reasons not well understood. So “fancy” fish have shorter life expectancies than “normal” fish. They are prone specifically to dropsy and swim bladder disease.
Many fish such as electric blue Jack Dempsey’s, electric blue acaras, parrotfish, flowerhorns and some OB Lake Malawi’s are very compromised genetically and typically do not live very long.
Now as with all things in Mother Nature there are exceptions to the life spans shown above. Here is a 21 year old blind cave tetra:
Stocking in Greater Depth
Hopefully the following links can put some common sense into this subject:
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