That Fish Blog – Aquarium Advice and Information

Hello, Frank Indiviglio here. I have always favored fishes that seem to straddle the line between the fish and reptile/amphibian kingdoms. Included among these are both marine and freshwater forms, including the toadfish, frogfish, lizardfish, lungfish, mudskipper (note the common names!) and others. The freshwater fish family Polypteridae, containing the bichirs and the reed or rope fish, has long fascinated me and seems very popular with visitors to the exhibits I have worked on at the Maritime Aquarium (Norwalk, CT) and the Bronx Zoo.

Few if any bichirs have been well-studied, and even the most commonly available species are rarely bred in captivity; much can be learned by the patient aquarist.

Description

The dorsal fin rays of these elongated, snake-like fishes are separated from one another, rising and falling in a series of humps and lending them the appearance of scaled-down dragons. This effect is most evident in the aptly named Senegal dragonfish (please see below). The pectoral fins are rimmed with fleshy lobes, and are paddle-like in shape and function.

Swimming takes the form of short bursts, but mainly these fish scull along the bottom. The largest, including the commonly sold reedfish, can reach 3 ½ feet in length, but most are considerably smaller. Although dissimilar externally, bichirs are believed related to sturgeons, paddlefishes and gars.

Range and Habitat

Bichirs are limited in range to tropical Africa and the Nile River system, and are usually associated with shallow, plant-choked waters such as marshes, swamps and the shores of slow-moving rivers.

Future Amphibians?

The amphibian-like qualities of the bichirs are not limited to appearance alone. The swim bladder has evolved into an accessory breathing organ, allowing them to breathe atmospheric oxygen and to survive out of water for some time…few species are rumored to voluntarily leave the water for short periods. The young of some species even sport external gills, much like salamander larvae!

Reed or Rope Fish, Erpetoichelys calabaricus

This brown West African native has a sinuous, snake-like body and a wide mouth. The reedfish hides under the mud by day, emerging at night to feed upon insects, fishes, worms and frogs. It can reach a length of 3 ½ feet, but rarely attains that in captivity.

Senegal Dragonfish or Cuvier’s Bichir, Polypterus senegalus

Rounded, widely-separated dorsal fin rays lend the Senegal dragonfish an uncanny resemblance to its mythical namesake…it really does look like a miniature dragon!

Senegal dragonfishes are distributed throughout the Congo Basin and reach 12 inches in length. They make hardy, interesting aquarium pets and often learn to anticipate feeding times. The effect of a large specimen in a well-planted aquarium is quite spectacular – they definitely deserve more attention from aquarists.

Ornate Bichir, Polypterus ornatipinnis

Swamps and marshes in West Africa are the home of this commonly imported bichir. Patterned with a lacework of black markings, the ornate bichir is one of the more attractive members of its family.

Unfortunately, due to its unique appearance, the ornate bichir is often purchased on a whim. Few realize that the youngsters sold in pet stores eventually grow to 18 inches in length, and are often aggressive towards tank mates. However, properly accommodated ornate bichirs make fascinating pets, and, as they are rarely bred in captivity, are ideal species to study.

Further Reading

You can read more about bichirs, and see a list of all recognized species, at http://www.fishbase.com/NomenClature/ScientificNameSearchList.php?crit1_fieldname=SYNONYMS.SynGenus&crit1_fieldtype=CHAR&crit1_operator=EQUAL&crit1_value=polypterus&crit2_fieldname=SYNONYMS.SynSpecies&crit2_fieldtype=CHAR&crit2_operator=contains&crit2_value=&group=summary&backstep=-2.

I’ll address captive care in more detail in the future. Until then, please write in with your questions and comments. Thanks, until next time, Frank Indiviglio.

Polypterus senegalus image referenced from Wikipedia and originally posted by Zhyla

Rope fish image referenced from Wikipedia and originally posted by Michael Zalewski