- West African lungfish, Protopterus annectens
- 4 year(s)
- Not Applicable ()
The fish that can survive for the longest time in the wild without feeding is the West African lungfish (Protopterus annectens). Native to such countries as Senegal, Niger, Gambia, Sudan, Cote d’Ivoire, Sierra Leone and Guinea, it can survive for as long as four years (and possibly up to five) without food during periods of severe drought when rivers and lakes in which it normally lives sometimes dry up. It achieves this extreme feat by burying itself in mud at the bottom of the river or lake and then producing a protective cocoon around itself, inside which it enters a state of suspended animation or torpor called aestivation. During this state, the lungfish does not eat, drink or excrete until the rains come again, refilling the dried-out rivers and lakes, at which point the lungfish breaks out of its cocoon and lives normally once more.
There are six species of lungfish currently known to exist today, all of which occur only in freshwater, and with a very disparate zoogeographical distribution. Four species exist in Africa, one in South America, and one, the most primitive, in Australia. Reports of a mysterious lungfish-like creature also existing in Asia have not been confirmed so far. Genetic studies indicate that lungfishes are the fishes most closely related to tetrapods (four-limbed vertebrates), and they have the largest genome (gene complement) of any vertebrate.
This mean that lungfish can spend a large proportion of their life in this state of torpor. The longest-lived African lungfish in captivity is 18 years, though there are a few unconfirmed reports of specimens exceeding 20 years old.