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Becker, George C. / Fishes of Wisconsin

Bullhead catfish family - ictaluridae,   pp. 693-732 PDF (19.6 MB)

Page 730

730   Bullhead Catfish Family-Ictaluridae 
then fertilized by the male. At this time the two fish lay 
side by side, with heads in the same direction, turning their 
bellies together. At times the female quit the nest for a few 
minutes while the male fluffed and arranged the eggs. 
During this observation the egg-laying was carried out in 
about four and one-half hours. Within an hour after the 
female had quit spawning she was removed from the tank, 
as past experience had shown that she would crush or eat 
the eggs. The male took up guard over the nest at once. 
  Observers of flathead catfish spawning noted that 
when the male settled over the mass of eggs after 
spawning, he ventilated them strongly with his ven- 
tral fins, created a current of water with his anal fin, 
and fluffed the eggs by lifting the egg mass with his 
ventral fins; he also turned the eggs in a half-arc by 
using his mouth or ventral fins to move the egg mass, 
and by slipping his caudal fin under the egg mass he 
gave it a good shaking in a movement much more 
violent than one would expect to see. The male con- 
tinued to drive away the female or any other fish 
coming near the nest: he fought fishes of his own size 
or smaller and gently eased the larger fishes away. 
  In Texas hatchery pens, the males were vicious 
while guarding eggs, and would "tear the female to 
pieces" if she attempted to enter the spawning jar 
containing the eggs (Henderson 1965). Henderson also 
noted that a number of females that had spawned 
had been killed by the male, even though laboratory 
workers tried to remove the female as soon as pos- 
  The egg mass of the flathead catfish in the Shedd 
Aquarium contained an estimated 100,000 eggs. The 
size of the flathead catfish spawn varies, depending 
on the size of the female. Snow (1959) reported an 
egg mass which weighed slightly less than 1,089 g 
(2.4 lb), and contained about 15,000 eggs. In small 
hatchery-reared brood fish, the spawns numbered 
from 3,000 to 5,000 eggs (Henderson 1965). In Kan- 
sas, three females, 305-610 mm TL, held 6,900-11,300 
eggs, averaging 2.8-3.2 mm diam (Minckley and 
Deacon 1959). 
  In Oklahoma, estimates of the fecundity of flat- 
head catfish ranged from 4,076 to 31,579 eggs for fish 
1.05-11.66 kg (Summerfelt and Turner 1971). Ripe 
eggs averaged 3.7 mm diam. Forty-five percent of the 
sexually mature females probably did not spawn, and 
mature eggs of the unspawned females were re- 
  Giudice (1965) reported that the hatching of flat- 
head catfish eggs occurred in 6-7 days at 23.9-27.8*C 
(75-82°F); Snow (1959), reported hatching in 9 days 
at 24-25.9°C (75-78.6*F), into fry which were about 
11 mm long. 
  The male flathead continues to guard the young 
after hatching. The young remain tightly schooled for 
several days while the large yolk-sac is being ab- 
sorbed. Cross (1967) noted that by mid-June the young 
leave the nest, and are afterward found mostly on 
shallow riffles, beneath stones or other cover. Young- 
of-year flathead catfish feed mainly on aquatic insect 
larvae, induding Chironomidae, Ephemeroptera, and 
  The age and growth of flathead catfish are deter- 
mined in most studies by analyzing the rings on sec- 
tions of the pectoral spines. From one to three early 
annuli are missing on some of the spines from larger 
fish (Muncy 1957). 
  In the Mississippi River bordering Iowa (Schou- 
macher 1968), flathead catfish, ages II to XVI, dem- 
onstrated the following growth: 11-356 mm; III--406 
mm; IV-462 mm; V-533 mm; VI-556 mm; VII- 
686 mm; VIII-663 mm; IX-655 mm; X-620 mm; 
XI-734 mm; and XVI-864 mm. In an earlier study 
(Barnickol and Starrett 1951) of catfish from the Iowa- 
Illinois sections of the Mississippi River, the growth 
in older flatheads appeared to be substantially greater: 
1-193 mm; 11-297 mm; 111-373 mm; IV-429 mm; 
V-490 mm; VI-561 mm; VII-608 mm; VIII-795 
mm; IX-895 mm; X-838 mm; XI-902 mm; XIII- 
940 mm; and XIV-978 mm. 
  A 1.12-m, 24.95-kg (44.1-in, 55-1b) flathead catfish, 
caught 23 August 1974 from the Fox River at Eureka 
(Winnebago County), had the following calculated 
lengths for each year of growth: 1-109 mm; 2-234 
mm; 3-404 mm; 4-497 mm; 5-528 mm; 6-559 mm; 
7-606 mm; 8-652 mm; 9-683 mm; 10-698 mm; 
11-745 mm; 12-776 mm; 13-833 mm; 14-884 mm; 
15-962 mm; 16-976 mm; 17-1,008 mm; 18-1,024 
mm; 19-1,040 mm; 20-1,048 mm; 21-1,063 mm; 
22-1,071 mm; 23-1,087 mm; and 24-1,100 mm 
(Paruch 1979). 
  In Oklahoma (Turner and Summerfelt 1971), the 
average KTL for 124 females and 90 males was 1.30 
and 1.25 respectively. 
  Carlander (1969) noted that the growth of flathead 
catfish was more rapid on shallow mud flats than in 
clear rocky areas. Minckley and Deacon (1959) sug- 
gested that in Kansas the flathead catfish grew faster 
in the Big Blue River than in the Neosho River, be- 
cause it fed on fish at an early age. 
  In the Mississippi River, flathead catfish mature at 
ages IV or V (Barnickol and Starrett 1951). The size 
at maturity varies considerably: a few are mature at 
381 mm (15 in), but most are not mature until they 
reach 457 mm (18 in). According to Minckley and 
Deacon (1959), the loss of the light patch at the tip of 

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