James A. Steeby

Daytime mechanical water circulation of channel catfish ponds

Abstract The effect of midday mechanical water circulation on water quality and production of channel catfish (Ictalurus punctatus) was studied in six, 1·62-ha, 1-m average depth, earthen ponds. Ponds were stocked in spring 1990 and 1991 with 14 800 fingerling channel catfish/ha; fish were harvested in late fall and winter each year. A horizontal, axial-flow, 2·24-kW water circulator was placed in three ponds and run for 6–8 h daily during each of the two summer growing seasons. Relative to ponds without circulators, midday water temperatures and dissolved oxygen concentrations varied little with depth, demonstrating that circulators effectively mixed pond waters. Circulation did not reduce the incidence of critically low nighttime dissolved oxygen concentrations (P > 0·05), but reduced the total hours of supplemental aeration required to support fish production by a factor of 0·58. Phytoplankton abundance, total and un-ionized ammonia-nitrogen concentrations, and nitrite-nitrogen concentrations were unaffected by circulation (P 0·05). Although the reduction in aerator use in circulated ponds was impressive, power cost savings for aeration were largely offset by cost of daily circulator operation.

Optimizing copper sulfate treatments for fungus control on channel catfish eggs.

This range-finding study determined the optimum concentration of copper sulfate (CuSO4) for fungus control on eggs of channel catfish Ictalurus punctatus. The study consisted of five CuSO4 concentrations (2.5, 5, 10, 20, and 40 mg/L) and an untreated control in a flow-through system. A single spawn was used for each replication (N=4). Eggs were treated daily until the embryos reached the eyed stage. When hatching was complete for all viable eggs, fry were counted to determine the percent survival in each treatment. Fungal growth was severe in the untreated controls; survival of hatched fry in the control group was approximately 2%. The optimum CuSO4 treatment, as determined by percent survival of hatched fry, was 10 mg/L daily (69% survival); survival for this treatment group was significantly different from that for the controls. Very little fungus was present in treatments receiving 10-mg/L CuSO4 or higher except in one replication that had approximately 40% unfertilized eggs. The average survival rates in the 0-, 2.5-, 5-, 10-, 20-, and 40-mg/L CuSO4 treatments were 2, 34, 50, 69, 59, and 51%, respectively.

A Length–Weight Relationship for Channel Catfish Grown under Commercial Conditions in Mississippi

Abstract A length-weight relationship was developed for channel catfish (Ictalurus punctatus), 13–67 cm total length, grown under commercial conditions in Mississippi. In total, 8,885 fish were sampled from ponds stocked at 11,100 to 19,800 fish/hectare. Predicted weight from total length is based on the equation log e (weight, g) = 0.27357209 + 0.25646117 cm – 0.003298348 cm2 + 0.0000184 cm3 (r 2 = 0.9885). This relationship is very similar to that found for pond-raised channel catfish in Kansas, but weights for pond-raised fish up to 55 cm total length were greater than those for wild channel catfish in Alabama.

Laboratory Dose Confirmation of Copper Sulfate for Treating Fungus on Channel Catfish Eggs

Abstract Two dose confirmation studies are required by the U.S. Food and Drug Administration to verify the effectiveness of a candidate before approval as a new animal drug is awarded; the two studies provide independent substantiation of the results. This laboratory study was designed to compare an untreated control and a 10-mg/L copper sulfate (CuSO4) treatment to control fungus (Saprolegnia spp.) on eggs of channel catfish Ictalurus punctatus at 23.5°C in a flow-through system. The eggs were treated once daily until the embryos reached the eyed stage (five treatments). When hatching was complete for all viable eggs (day 10), the fry were counted to determine the percent survival in each treatment. Infestation by a fungus identified morphologically and by polymerase chain reaction as Saprolegnia spp. was severe in the control fish, resulting in 8% survival. The mean percent survival of fry hatched from the CuSO4-treated eggs was significantly higher (mean, 55%; range, 27–71%).

Evaluation of a Fingerling-to-Stocker Phase as Part of a New Production Strategy for the Commercial Farming of Channel Catfish

Abstract Within a three-phase production strategy for farming channel catfish Ictalurus punctatus, the second phase, fingerling to stocker production, was evaluated. A complementary economic analysis compared the cost of producing stockers, food-size fish net returns, and overall cost of production for a three-phase production system with that of the traditional multiple-batch system. Pond run fingerlings (mean length = 10.7 cm; mean weight = 10 g) were stocked into 0.05-ha experimental earthen ponds at densities of 98,840, 123,550, and 148,260 per hectare. They were fed floating fingerling feed with 36% crude protein to satiation during a 180-d grow-out period. At harvest, mean survival (63.7–72.6%) and mean feed conversion ratio (1.5–1.6) did not differ significantly among treatments. Mean harvested biomass (kg/ha) ranged from 5,766.5 to 9,135.6 and increased as density increased. Mean harvest weight (85.8–94.3 g) decreased as density increased but was not statistically different among treatments. Stock...

A Centimeter-Based Length–Weight Relationship for Channel Catfish Fingerlings Grown under Commercial Conditions in Mississippi

Abstract A length-weight relationship was developed for channel catfish fingerlings (Ictalurus punctatus), 5–24 cm total length, grown under commercial conditions in Mississippi. A total of 2,535 fish were sampled from ponds stocked with 30,000-33,000 fish/ha. Predicted weight from total length in centimeters is based on the equation: log e (weight, g) = –2.377201249 + 0.629764601 cm – 0.02225206 cm2 + 0.000353920 cm3 (r 2 = 0.9789). The “standard” inch-based length–weight equation used for commercial sale of channel catfish fingerlings compares well to the centimeter-based relationship given here.

Production and Associated Economics of Channel Catfish Fed Different Practical Diets in the Fingerling–Stocker Phase of Culture

Abstract Two practical diets that differed in cost based upon protein sources were evaluated as treatments relative to production and associated economics of the fingerling–stocker phase of culture for channel catfish Ictalurus punctatus. The commercially manufactured fingerling feeds contained approximately 35% crude protein and were fed to fingerling channel catfish (mean weight = 13.8 g; mean length = 12.2 cm, respectively) stocked into experimental earthen ponds (0.05 ha) at a density of 123,550 fish/ha. There were five replicates (ponds) per treatment. The fish were fed daily to satiation, unless some physical or biological factor warranted an abstention of one or more days. After 180 d, all ponds were harvested by seine and then completely drained. Mean individual harvest weight and length of fish fed the high-cost practical diet were significantly greater than those of fish fed the low-cost diet. Survival and feed conversion ratios were not significantly different between dietary treatment groups. ...

Safer High-Density Polyethylene Plastic Paddles for Hatching Channel Catfish Eggs

Abstract A new paddle made from high-density polyethylene plastic has been devised for use in egg hatching troughs. This paddle is very safe as it will paddle properly through water and can be stopped easily when grabbed by hand. The plastic used to fabricate this paddle is 1/8 inch thick and cut from a drum with a reciprocating saw. New 30-gal drums, made of food-grade federally approved high-density polyethylene can be purchased for about US

Dose-Confirmation of Copper Sulfate for Treating Fungus on Channel Catfish, Ictalurus punctatus, Eggs at a Commercial Hatchery

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Comparison of Seines Equipped with Rubber Roller or Gathered-Netting Mud Lines for Harvesting Channel Catfish in Earthen Ponds

This study at a commercial hatchery was required by the U.S. Food and Drug Administration to provide independent substantiation of the results of previous laboratory dose-confirmation studies on the use of copper sulfate (CuSO4) to control fungus (Saprolegnia spp.) on the eggs of channel catfish, Ictalurus punctatus. The study compared an untreated control group of eggs to eggs treated with 10 mg/L CuSO4 in a flow-through system; mean water temperature was 23.5°C. Eggs were treated once daily until the embryos reached the eyed stage (5 treatments). Hatching was complete by day 11, and fry were counted to determine the percentage of survival in each treatment. Fungus was identified by polymerase chain reaction (PCR) as Saprolegnia spp. The mean survival in the control treatments was 4% and 40% in the CuSO4 treatments; the latter survival was significantly higher, but still lower than normal. This study confirms that 10 mg/L CuSO4 is an effective treatment to control fungus on catfish eggs when used daily until the eggs are eyed. However, continued treatment of eggs until hatching occurs may be warranted based on fungal growth rates observed after treatments were discontinued.