Fish in Focus:  Bowfin young-of-year, Amia calva



Juvenile bowfin, Amia calva
Jan J. Hoover

These young-of-year bowfin were collected 08 May 2002 from a small floodplain pool in the Bayou Meto drainage, Arkansas. Most fish were <60 mm TL. Fins and the posterior margin of the head were bright orange with black borders.

The pool was the last in a chain of four, small (<75 m 2 ), shallow (< 25 cm deep), warm (24-28 C), and hypoxic (2.3-2.7 mg/l). More than 90% of the surface area was covered by vegetation: ludwigia, duckweed, forbs, and grasses. Bowfin were abundant and some were brought back for experimental work at the U.S. Army Engineer Research and Development Center at Waterways Experiment Station.


Juvenile bowfin, Amia calva
Jan J. Hoover

They adapted quickly to aquarium life, feeding on frozen bloodworms, but within a week, several had died with their mouths agape. Photo below shows three that died within a few hours of each other and material that was expelled from their mouths: remains of bloodworms and the bodies of tapeworms.


Juvenile bowfin, Amia calva
Jan J. Hoover

By 24 May 2002, all of the young bowfin had died. All individuals prior to death expelled their gut contents, most of which consisted of large tapeworms. Bowfin frequently carry large and distinctive parasite loads, but direct evidence suggesting that the parasites can kill the fish is rare.

 

© 2015 North American Native Fishes Association