Glycerol is the main by‐product of biodiesel production from vegetable oils and animal fats. It has been evaluated as an energy source for several farm animals. A study was conducted to examine the effects of various levels of glycerol in channel catfish, Ictalurus punctatus, diets. Fish with mean initial weight of 6.8 ± 0.1 g were stocked in 110‐L flow‐through aquaria and fed practical diets containing 0, 5, 10, 15, and 20% glycerol for 9 wk. There were no significant differences in feed consumption, weight gain, feed efficiency ratio, and liver lipid level among fish fed diets containing 0, 5, and 10% glycerol. However, fish fed diets containing 15 and 20% glycerol had reduced weight gain, feed efficiency, and liver lipid content. Survival was not affected by dietary glycerol levels. Blood glucose level was significantly higher in fish fed 5% glycerol than fish fed other diets. Fillet protein and fat generally decreased and fillet moisture increased as dietary glycerol level increased. It appears that channel catfish can utilize about 10% glycerol in the diet without adverse effects on feed consumption, weight gain, feed efficiency ratio, hemoglobin, hepatosomatic index, and liver lipid.

Simple and portable methods for assessing the physiological state of channel catfish Ictalurus punctatus would be valuable tools in field situations where problems with blood storage and transportation occur. This study compared the use of handheld lactate and glucose meters with established laboratory methods in stressed (fatigued) and unstressed (control) channel catfish fingerlings. The results obtained from the Accutrend (Roche Diagnostics Corp.) lactate meter and the Accu-Chek Advantage (Roche Diagnostics) glucose meter were consistently lower (P , 0.05) than those obtained with the laboratory reference method. However, significant differences (P , 0.0001) were found between the control and fatigued fish for both lactate and glucose, regardless of the method of analysis. Both handheld meters were found to be reliable and suitable for use in field or laboratory situations where relative measurements are acceptable. The costs associated with using the handheld meters were higher than those associated with accepted laboratory methods; however, the initial capital investment was lower for the handheld meters. Ease of use, portability, and rapidity of sample analysis make the handheld meters attractive alternatives to traditional laboratory methods.

Four new species of Henneguya (myxosporidan) are described from Ictalurus punctatus Rafinesque (channel catfish). They are as follows: Henneguya postexilis sp. n. and Henneguya longicauda sp. n. from the gills; Henneguya adiposa sp. n. from the adipose fin; and Henneguya diversis sp. n. from the liver, kidney, connective tissue of muscles and fins, and tumor-like external growths. Henneguya pellis sp. n. is described from the dermis of Ictalurus furcatus (LeSueur) (blue catfish). The development stages of all described species are discussed. Henneguya exilis Kudo was found on the gills of one I. punctatus; notes on its spore characteristics are presented.

Four hauling trips of approximately 6 h each were conducted to investigate effects of loading density on survival of golden shiners Notemigonus crysoleucas. Commercially graded golden shiners (mean weight 6 SE, 3.3 6 0.04 g) were transported at densities of 120, 180, and 240 g of fish/L of water in insulated hauling tanks that were filled with fresh well water, chilled with unchlorinated block ice, and aerated with pure oxygen. The criterion for determining success or failure was golden shiner survival. Transportation at a given density was deemed successful if survival both at trip's end and at 18 h postdelivery was at least 99%. At all three hauling densities evaluated, survival exceeded 99% both at trip's end and at 18 h postdelivery. Furthermore, increasing loading density had no effect on whole-body cortisol concentrations, demonstrating that no significant stress response occurred. Un-ionized ammonia concentration increased with loading density (range, 0.05-0.46 mg/L) but had no effect on fish survival. Results of this study indicate that golden shiners can be successfully (!99% survival) transported for up to 6 h at a density of 240 g/L in well water chilled with unchlorinated block ice and aerated with pure oxygen. Higher loading densities could mitigate the effect of escalating transport cost for commercial farmers.

Commercially produced, food‐size channel catfish Ictalurus punctatus that were harvested using routine procedures had significant elevations in plasma cortisol, glucose, and lactate compared with preharvest fish captured from open ponds. Blood samples were taken from 10 fish in each of two treatments (liquid oxygen diffuser‐ and paddlewheel‐aerated holding socks) and four sampling periods (before harvest, after socking, before loading, and before unloading) during each of 10 harvest events. Water column temperatures averaged approximately 27°C during the study. Ten fillet samples were taken from fish held overnight in paddlewheel‐ and liquid oxygen‐aerated holding socks during some harvest events. Mean plasma cortisol levels averaged 3.02 ng/mL before harvest, 84.38 ng/mL immediately after socking, 135.22 ng/mL after 18 h in the sock (i.e., before loading onto the truck), and 128.54 ng/mL after 2–3 h on the truck (i.e., before unloading). Mean plasma glucose levels averaged 34.7 mg/dL before harvest, 95.41 mg/dL after socking, 134.53 mg/dL before loading, and 134.86 mg/dL before unloading. Mean plasma lactate levels averaged 2.43 mmol/L before harvest, 13.24 mmol/L after socking, 11.53 mmol/L before loading, and 7.88 mmol/L before unloading. These results should not be considered maximal until additional studies are conducted with average water temperatures at their highest. There were significant changes within treatment over 7 d of refrigerated storage for fillet pH, color, and drip loss; however, there were no consistent trends between treatments. Results indicate that routine capture and hauling procedures are stressful to commercially produced, food‐size channel catfish under the examined conditions and that using liquid oxygen for aerating fish in holding socks does not significantly improve fillet quality or reduce stress levels.