EPOW - Ecology Picture of the Week

Catfish (Clarias sp., prob. C. lazera), 
Family Clariidae, Order Siluriformes
Ubange River, Congo, Africa

Explanation:   Tonight's dinner: fresh catfish!  We are in a pirogue (dugout canoe) on a remote section of the Ubange River straddling the "two Congos" (Democratic Republic of the Congo, and Republic of the Congo) in equatorial Africa.  We have happened upon this fellow selling his catch of the day, a local catfish, otherwise known by its scientific name of Clarias lazera.   

In August and September 2004, I engaged in an expedition to the roadless interior of the Congo to assist with community-based forest conservation.  The interior Congo is a vast swamp forest, however, and fish play a vital part in the resources of the local people, more so than does timber.  

Daily fish hauls are a key, and one of the only, sources of protein in this region, where people otherwise use shifting (slash-and-burn) cultivation in the forests and plant mostly manioc and maize (starches).  

This fish species and the related species Clarias batrachus in south Asia are sometimes called "walking catfish" because at times of drought they may leave their pools and "walk" (squirm) overland to the next pool.  (View a short mpg video here of their overland locomotion.)  Thus, the family of this fish -- Clariidae -- is sometimes referred to as the airbreathing catfishes, although they have gills like other fishes and not lungs.  

Alternately, catfish of this genus may burrow into the mud and wait out dry periods, leaving the burrows at night to feed.  Local people often know where to find their burrows and capture them using specially-crafted spears with backward-pointing barbs.  This can be an important source of food (especially protein) during dry periods, so local knowledge of where to find the burrows and how to extract the fish can be vital to the survival and health of families living in the remote regions of central Africa.  

Typical local villager fishing in the Ubange River, using a trident-like fishing spear.  He is standing with remarkable balance in his pirogue canoe, which has little freeboard.

Clarias catfish are sometimes considered "noxious" species when introduced elsewhere, such as in Poland, although Clarias lazera has been considered for aquaculture.  In the Nile River, however, this species has been shown to "bio-accumulate" metals such as mercury, iron, and copper in its muscle and liver.