Polypterus endlicheri endlicheri- an introduction and primer
Many of you know that I have a certain fondness for large (monster) primitive fish. I would like to take a few minutes to give some more information on the this particular species, as well as a bit of a history lesson and overview on the care and feeding of this very unique and special fish.
Polypterids date back over 100 million years in fossil records and are among the most primitive of the ray-finned fishes. Their fossil distribution ranges from South America to Africa and their adult size, depending on species can range from ten inches to around three feet long.
They are a shallow water species, often swimming in the weeds and plants near shore in Central and West Africa. They are relatively long-lived in captivity, usually living 10-15 years and sometimes longer depending on quality of care.
They have a few very interesting and unique features the first of which is a divided swim bladder, the right side of which is significantly larger. This allows the polypterus to be able to breathe in or out of water, which means it can survive a substantial amount of time out of water as long as it retains its moisture. This also means that, similar to ananbantoids, they require surface space above the water line to breath. They also are born with feathery external gills, similar to amphibians, which they lose as they mature, generally by 3-4 inches in length though this can vary.
There are two main groups of polypterids, upper and lower jaw. Polypterus endlicheri endlicheri belong to the lower jawed group and they generally reach a maximum captive size of 28-32″. Polypterus are relatively easy to feed and most frequently are pellet trained very quickly. In the wild, they eat fish and invertebrates so are easy to supplement with frozen foods or even chopped earthworms, etc.
Some important considerations for their tank set-up are size and safety. While polypterus are not particularly “active”, they are diurnal and known for their ability to get out of tanks quite successfully especially at night. A tight-fitting lid is an absolute must. It is best for the lid to be entirely secure, and preferably weighted down (or heavy glass) at least for the introductory period after acclimation. Since their bodies are relatively rigid, it is also important to make sure the tank has enough distance, front to back, for them to be able to turn adequately.
They grow quickly for the first year or two, often reaching 12-15″ in less than a year. Once they hit that size, they tend to plateau and grow a few inches a year until they reach their fully mature size of about 30″. I have had mine for 4 or 5 years and they are just now reaching the 22″ mark, after quickly reaching 15″ in the first year. Because of this relatively plateaued growth, it is possible to maintain them in a grow out tank for some time. The height of the tank is not very relevant, as they are from shallows but they do need adequate length and turning space.
Plants that can be anchored sturdily do well, or floating plants. I use a few very large pieces of wood which inhabit the mid-water in my tank for decor. Polys are very social, and do well in groups but please keep in mind that they need to be of like size in order to prevent cannibalization. Polypterids are not at all aggressive, but opportunistic and will readily eat any fish that they can fit in their large mouths, including same species.
I don’t think I have ever kept a fish that I enjoy even remotely as much as my polypterus. They beg at the glass whenever people enter my fish room and are able to be hand fed (carefully with tongs). They “dogpile” together and are very entertaining to watch. They are a very sturdy fish, tolerant to many water conditions and temperatures with high 70s being ideal for this species with a wide range of pH and hardness being suitable.
Probably the best resource for more information out there is found at this link from MFK: http://www.monsterfishkeepers.com/forums/showthread.php?65770-Polypterids-an-introduction-and-primer-3-0
Recommended tankmates are quiet diverse, with the one rule being that they need to be substantially bigger than the polypterid’s mouth when open. I prefer to keep them with other primitive fish, specifically gar, but many have good luck keeping this species with large cichlids.
In closing, I could talk about their history, keeping, and behavior all day as they are a truly amazing fish that are hardy and rewarding. One must be prepared to have a quite large tank for them at maturity, with 7′ (or longer)x3’x3′ being optimum for a few specimens.