Fish Lifespan and Ageing: From Annual Killifish to Koi
Recorded lifespans of common aquarium and pond fish from AnAge, how temperature and growth rate affect ageing, and the age-related changes documented in studied species.
Overview
Fish lifespans vary enormously between species, so no single figure describes how long fish live. The AnAge database of animal ageing and longevity (genomics.senescence.info) records maximum longevity for individual species and notes whether the record comes from captivity or the wild. Maximum longevity is the longest reliably recorded life, not the typical lifespan. Most individuals die younger, and the figure depends on the quality and size of the data.
Lifespan records by species
| Species | Maximum longevity (AnAge) | Notes |
|---|---|---|
| Turquoise killifish (Nothobranchius furzeri) | 1.1 years (captivity) | Shortest-lived vertebrate bred in the lab; one laboratory strain reportedly lived at most 32 weeks |
| Siamese fighting fish (Betta splendens) | 2 years | Reproductive senescence documented |
| Guppy (Poecilia reticulata) | 5 years (wild) | Gradual ageing, including reproductive senescence |
| Japanese medaka (Oryzias latipes) | 5 years (captivity) | Clear ageing phenotype, mortality rising with age |
| Zebrafish (Danio rerio) | 5.5 years (captivity) | Outbred fish average 3.5 years |
| Goldfish (Carassius auratus) | 41 years (wild) | Often short-lived as pets, but can possibly exceed 40 years |
| Common carp (Cyprinus carpio) | 47 years (captivity) | Same genus, Cyprinus, as koi |
Annual killifish
According to AnAge, Nothobranchius furzeri lives in a habitat with rainy and dry seasons and has two states: a fast-growing phase in the rainy season with rapid development, maturation and ageing, and a diapause in the dry season in which development is suspended. Lifespan differs strongly between strains. A 2006 study in Aging Cell described one strain with a maximum captive lifespan of only 3 months, while a 2025 review in Frontiers in Aging gives a range of 2 months to 1 year depending on the strain. Wild-derived populations can live over a year in the laboratory.
Koi
Koi are domesticated carp selected for colour; Wikipedia classifies them as Amur carp (Cyprinus rubrofuscus). Their longevity is poorly documented. Wikipedia reports claims of 100 to 200 years and a 1974 scale-ring study that put one koi, named Hanako, at 226 years, but notes that some sources accept an age of little more than 50 years for the species. These record claims have not been independently verified. AnAge's 47-year captive record for common carp is a documented reference point for the group.
Factors that influence lifespan
Temperature: a 2015 review in Biogerontology found a clear trend, from cold-blooded animals to mammals, of lower temperature being linked to longer lifespan, both in the wild and in the laboratory. In Nothobranchius furzeri, lowering water temperature from 25 °C to 22 °C increased median and maximum lifespan, slowed the onset of age-related decline in movement and learning, and reduced the build-up of the age pigment lipofuscin (Aging Cell, 2006). In Nothobranchius rachovii reared at 20, 25 and 30 °C, lower temperature increased cellular protein-degradation activity in muscle, which the authors link to its life-extending effect (Age, 2015).
Growth rate: in three-spined sticklebacks (Gasterosteus aculeatus), brief exposure to cold or warm water early in life altered growth trajectories. Fish that later grew faster to catch up had a 14.5% shorter median lifespan, while fish whose growth was slowed lived 30.6% longer, even though all groups reached the same adult size (Proceedings of the Royal Society B, 2013).
Genetics and population history: lifespan differences between Nothobranchius furzeri strains have been genetically linked to sex. In guppies, populations from environments with higher extrinsic (external) mortality matured earlier but, unexpectedly, lived longer in the laboratory and showed no earlier onset of senescence (AnAge, citing Reznick and colleagues).
Signs of ageing in studied species
- Spinal curvature: a common age-related change in zebrafish, also seen in ageing Nothobranchius furzeri.
- Reduced activity and performance: zebrafish show an age-related decline in exercise capacity and trainability, and ageing turquoise killifish show locomotor and learning deficits.
- Body condition: ageing Nothobranchius furzeri become emaciated, while old medaka in one study became large, pale, bloated and sluggish.
- Reproductive senescence: documented in guppies and Siamese fighting fish.
- Bone and tissue changes: zebrafish lose vertebral bone mass with age, and lipofuscin accumulates in ageing turquoise killifish.
Caring for ageing fish
No fetched veterinary source sets out a specific care protocol for elderly aquarium fish. The documented changes do have practical implications. A curved spine in an older fish may be age-related, but infection, nutrition and injury can produce the same sign, so a sudden change deserves the same investigation as in a young fish; the guide on causes of fish deformities lists these causes. Slower movement and poorer body condition can make it harder for an old fish to compete with faster tankmates for food. Decisions about an aged fish that can no longer swim or feed are a welfare matter, covered in the humane fish euthanasia guide.