The Lifespan of Ornamental Marine Fish

Marine aquarium fishes can be long-lived animals, with some living for 40 years or more in an appropriate tank. While many saltwater aquarium fishes have much shorter lifespans, popular species such as various clownfish and tangs have been reported to be amongst the longest-lived aquarium fishes. In general terms, a well-cared-for aquarium fish will often outlive its counterpart on a wild reef, although poor husbandry can lead to a premature death in any aquarium animal.

  1. Larger Fish Usually Live Longer

    • While there are exceptions, there is believed to be a general correlation between a fish's adult size and its lifespan, with larger fishes living longer. Large surgeonfishes such as the whitemargin unicornfish (Naso annulatus) have been aged by scientists at well over 40 years, while some small gobies live less than a year. One interesting question is whether or not these smaller fishes are pre-disposed to have short lifespans even in the absence of predation and competition in the wild. Anecdotal evidence suggests that many species with short lifespans in the wild may live for many more years than previously expected with appropriate care in an aquarium setting.

    Premature Mortality in Aquarium Fish

    • While many saltwater aquarium fishes can be extremely long-lived in an appropriate marine aquarium, many die prematurely. Several factors can contribute to a fish not obtaining its natural lifespan in an aquarium, but husbandry is the one that aquarists can and should do everything in their power to control, especially when it comes to stability. An unstable aquarium with wildly fluctuating parameters can cause stress, which can lead to disease susceptibility and eventual death.

      Even if the aquarium's parameters are stable, keeping a fish in an aquarium with water parameters inappropriate for the species can dramatically shorten a fish's lifespan. For example, keeping a sub-tropical or temperate species in a tropical aquarium can lead to premature death. Likewise, keeping a fish in too small an aquarium can cause stress and other health related issues that may lead to premature death.

    Enhancing the Lifespan of a Saltwater Aquarium Fish

    • In addition to maintaining a stable environment appropriate to the fish's husbandry needs over the long term, aquarists can maximize the lifespan of their fishes by insuring an excellent diet of varied foods. Supplements and vitamins should be considered, especially for some species, and care should be taken to make sure each fish is eating on a daily basis. In addition to nutrition, reducing stress by choosing appropriate tank mates, providing suitable habitat and minimizing external stressors such as loud noises can go a long way toward lengthening the lifespan of your fish.

    Being Prepared for Problems

    • Many aquarists maintain a separate quarantine or hospital tank for fishes that may exhibit signs of disease, parasitic infestation, injury or stress. Quickly removing an affected fish to a quarantine tank for observation and treatment can be the difference between life and death for the fish in question, as well as other fishes in the aquarium. Rehabilitating a sick fish so it has the opportunity to achieve its full lifespan is not only the humane thing to do, but it's also often the most cost-effective action, especially when one considers replacing a show-sized angelfish, tang or butterflyfish may cost hundreds of dollars.