Old Killifish . . .
Just How Long Do They Live?
By Donna M. Recktenwalt
Among the many fish species available to aquarists, it is generally accepted as fact that many other species are longer lived than most of the killifish. This is certainly true; but just how long do killifish actually live?
In the wild, most annuals manage a year at most, if only because their habitat dries up. The fact that the fish has adapted to the (usually) annual droughts by fast growth, and by producing eggs that undergo a sometimes extended estavation (diapause) is what has enabled many species to survive where other fish could not.
However, not all “annuals” are true annuals. In the case of some Nothobranchius, for example, fluctuating water levels may allow for the successful hatching of diapause eggs deposited at various times and at various levels within the pool. This produces coexisting fry and adults of varying ages, which may allow older adults to survive longer if the pool fails to dry up completely.
Various studies have been conducted on the life span of annual killifish. Studies with Nothobranchius guentheri showed an average lifespan of about 14 months at 22C (72F). Studies with Cynolebias adolffi showed an average lifespan of 11.5 months at 22C (72F); and at 16C (61F) half of the fish were still alive at 19 months. Some keepers of Nothos have indicated that if you maintain them at cooler temperatures, some individuals may live up to two years or more.
“I’ve had a Cynolebias minimus go three years,” says Steve Halbasch. In March of 1997 he noted “I also have had the same trio of Aplyochelius katangae since 1991 and I just picked a dozen eggs yesterday.” Rosario La Corte supposedly had a C. lacortei that was 18 months old and successfully breeding. Oleg Kiselev reported having a three year old C. melanotaenia aff. female, a four year old Fundulopanchax gardneri male still fertilizing eggs and producing viable fry, and an Ap. johnstoni that was over four years old.
Basically, most killifish live short lives in the wild due to high temperatures, failing habitat (rapidly drying ponds), and heavy predation rates. In the fishroom, most of these factors can be controlled.
Perhaps the idea of an old Notho or a senior citizen Cynolebias isn’t such a contradiction in terms after all.
— GCKA Newsletter, October 1997