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A Comparison of Second-Year Growth of
Blue Catfish and Channel Catfish in Kentucky
JAMES H. TIDWELL AND
STEVEN D. MIMS
Community Research Service
Aquaculture Research Center
Kentucky State University
Frankfort, Kentucky 40601. USA
Abstract.—Second-year growths of blue catfish (Ictalurus
furcatus) and channel catfish (/. punctatus) were
compared in north-central Kentucky. Percent weight gain
was significantly higher (P < 0.05) for blue catfish than
for channel catfish. There were no significant differences
(P > 0.05) in feed conversion or survival. Blue catfish
showed more consistent growth and were easier to seine
than were channel catfish. Blue catfish should be evaluated
further in temperate regions.
Several attributes may make the blue catfish (Ictalurus
furcatus) an attractive alternative to channel
catfish (/. punctatus) for commercial culture
as food fish in certain regions of the country. Optimum
growing temperature for blue catfish is reported
to be about 24°C, compared to 30°C for
channel catfish (Collins 1988). Such moderate
temperature requirements could extend the growing
season of blue catfish in cooler regions of the
USA (Huner 1988). Also, blue catfish have a higher
dress-out percentage and are easier to seine than
channel catfish (Chappell 1979). The aggressive
nature of the blue catfish might be highly desirable
in areas with large fee-fishing markets (such as
Kentucky).
The blue catfish may be inferior to the channel
catfish as a cultured species due to slower growth
at sizes less than 1 Ib and less efficient feed conversion
(Huner and Dupree 1984). Several producers,
however, have reported that blue catfish
grow faster than channel catfish in the first year
(Collins 1988). Chappell (1979) indicated that
growth of the two species is similar in the first 2
years and that channel catfish perform slightly better.
Dunham (1979) found that third-year blue
catfish and channel catfish grew at the same rate
during the winter. However, these studies were
conducted in the Deep South (Alabama). Production
of the two species has not been compared in
cooler climates, such as Kentucky.
The objective of this study was to compargrowth and feed conversion in blue catfish and
channel catfish during the second growing season
(fingerling to harvest size) in north-central Kentucky.
On 4 May 1987, blue catfish and channel catfish
were stocked at a density of 6,175 fish/hectare into
triplicate 0.04-hectare earthen ponds (six ponds
total; Table 1). Ponds were about 1.5 m deep and
supplied with water from a reservoir filled by runoff;
water levels were maintained by periodic additions
to replace evaporation. Water temperature
and dissolved oxygen (DO; model 54A oxygen
meter, Yellow Springs Instruments Co.) were
monitored twice daily at a depth of 0.5 m. Ponds
were aerated if DO levels were predicted to reach
3.0 mg/L or less during the night. Fish were fed
in midafternoon with a commercial floating feed
(32% crude protein) at 3% of body weight daily.
Feed amounts were adjusted every 2 weeks based
upon an assumed feed conversion (amount fed/
weight gain) of 1.5. Periodic fish samples were not
taken because blue catfish do not tolerate handling
and harvest well (Collins 1988), especially at high
temperatures, and sampling causes channel catfish
to stop feeding (Lovell 1989). Fish were harvested
on 9 October 1987 (culture period, 156 d). All fish
were counted and total harvest weights were recorded
for each pond.
Student's /-tests (P = 0.05) were used for twomean
comparisons of stocking weight, harvest
weight, percent weight gain, weight of feed offered,
feed conversion, and percent survival (Dowdy and
Wearden 1983). Percentage data were transformed
(arcsine) before analysis (Steel and Torrie
1980).
Morning DO averaged 6.7 mg/L, and afternoon
DO 8.2 mg/L. Average monthly afternoon water
temperatures ranged from a high of 26°C in July
to a low of 20PC in October. The overall mean for
the culture period was 24°C, the temperature reported
to be optimum for blue catfish (Collins
1988).
There was a significant difference (P < 0.05) in
stocking weight for the two species (Table 1), but
no significant difference (P > 0.05) in harvest
weight, feed conversion, or survival. Survival was
low (75%) in one channel catfish replicate due to
TABLE 1.—Performance of blue catfish and channel catfish cultured for 156 d during second-year growth. Values
are means (SEs) for three replicate ponds. An asterisk indicates that the two means within a column are significantly
different (Student's /-test, P < 0.05).
Species
Blue catfish
Channel catfish
Stocking weight
(g)
85.8 (0.3)*
98.8 (3.2)
Harvest weight
(g)
594.6 (5.2)
577.5(55.5)
Weight gain8
(%)
593.3 (4.7)*
485.8 (74.3)
Feed
conversion6
1.3(0.1)
1.7(0.5)
Survival
(%)
99.3(1.2)
89.7(13.5)
a Percent increase from stocking to harvest.
b Feed conversion = amount fed/weight gain of fish.
an infestation of Ambiphrya sp. (which explains
the large SE for survival in Table 1). The elevated
feed conversion for channel catfish (1.7) may have
resulted from overfeeding in this pond. Feed conversion
for blue catfish (1.3) was somewhat better
than the 1.5 reported by Chappell (1979). Percent
weight gain was significantly greater for blue catfish
than for channel catfish (P < 0.05). Blue catfish
averaged a 593.3% gain, whereas channel catfish
averaged 485.8%. Chappell (1979) reported
larger weight gains, but stocked smaller fingerlings
and cultured fish for 208 d.
Growth of blue catfish in replicate ponds was
consistent compared to that of channel catfish, as
demonstrated by the low SEs for ponds containing
blue catfish (Table 1). Blue catfish were also more
easily seined, as observed by Chappell (1979). The
three ponds of blue catfish in this study yielded
100%, 100%, and 99% of the fish on the first seine
haul.
Chappell (1979) found that blue catfish and
channel catfish demonstrated similar second-year
growth in Alabama and that channel catfish were
slightly larger at harvest. Our study in Kentucky
found significantly faster second-year growth of
blue catfish. The overall mean temperature during
the study period (24°C) was the reported optimum
for blue catfish (Collins 1988). Chappell (1979)
did not report mean water temperatures for comparison,
but did remark that water temperatures
were unusually high at the July sampling, suggesting
that temperatures were closer to the optimum
for channel catfish.
The blue catfish warrants further examination
as a cultured species, especially in regions with
temperate climates, large pay markets, and singleseason
production systems, for which size consistency
is important.
Acknowledgments.—We thank Julia Clark, Keith
Crabtree, Richard Knaub, Eddie Reed, Jr., Karla
Richardson, and Danny Yancey for assistance.
This investigation was supported by a grant from
the U.S. Department of Agriculture, Cooperative
State Research Service, to Kentucky State University
under agreement KYX-1283000009.
References
Chappell, J. A. 1979. An evaluation of twelve genetic
groups of catfish for suitability in commercial production.
Doctoral dissertation. Auburn University,