Channel catfish Ictalurus punctatus fed based on standard winter feeding recommendations lost weight in ponds during winter feeding studies. The objective of this study was to quantify feed consumption over the winter. Six concrete vats with a volume of 5 m³ were stocked in October 2007 with sub-market size fish (mean weight 0.25 kg) and market size fish (mean weight 0.72 kg).  Water was supplied by a pump on the bottom of an adjacent pond at 10.6 l/min.  Feed (32% protein full-sink pellet) was offered daily in feeding trays at a weight of 2% of total body weight of fish every afternoon.  After 15 minutes, trays were pulled up and remaining pellets were counted.  All vats were harvested 16 March 2008. Channel catfish consumed from 0.1% to 0.7% of their body weight daily over the winter when offered feed every day.  While catfish ate more at higher water temperatures, they continued to eat at temperatures as low as 7^oC. Compared to standard winter feeding recommendations, daily feed consumed by catfish was slightly (0.2 - 0.3%) less than the recommended daily percent of body weight to feed (at temperatures > 10 C).  However, the recommended frequency of feeding resulted in weekly recommended feed quantities lower (1.3% - 1.6%) than actual quantities of feed consumed by catfish.

Accurate and cost-effective inventory estimation of multiple-batch catfish crops would improve financial and production management. Several inventory estimation methods used by industry consultants and advisors are based on feeding response by fish. Datasets from experimental trials of catfish production in both single and multiple batch systems at various densities were used to estimate and compare the variation in feeding rates.  A coefficient of variation (CV) of quantity of feed fed per treatment was calculated for each week for each pond within three temperature ranges. Analysis of variance (ANOVA) was used to compare CVs calculated using daily feed, two-day means, three-day means and four-day means for each temperature range, for each stocking density and feeding treatment, for both single and multiple batch. Stocking density and temperature had no significant effect on variation of feeding rates in either single or multiple batch production. However, in single batch production, the four-day average of daily feed showed a significantly lower CV (17%) than daily feed (mean CV= 38%), two-day means (mean CV= 27%) or three-day means (mean CV= 24%). In multiple batch production, the three-day average of daily feed had a significantly lower CV (24%) compared to the daily feed (mean CV= 49%) and 2-day average (mean CV= 34%) but was not significantly different from the four-day average (mean CV= 23%).

Periodic grading and harvesting of fish increases production in some types of aquaculture by removing larger sizes of fish repeatedly throughout the growing season.  This reduces overall biomass and may allow smaller fish to obtain faster growth.  The objectives of the study were:  1) to determine the effect on production performance of repeated grading and harvesting larger sizes of fish throughout a 2-year growing season, using the traditional live car and UAPB grader; and 2) to determine whether more frequent harvesting and grading with the UAPB grader results in better growth and greater harvested yields of catfish.  Two two-year pond studies were conducted.  The first study (2005-2006) was designed to compare fish production over 2 years when graded and harvested with a standard live car as compared to the UAPB grader.  The second study (2007-2008) compared the effects of harvesting either 2, 3, 4, or 5 times a year on growth and yields of catfish.  Both studies were stocked initially with 5-inch fingerlings stocked at 6,000/ac and 1.0 lb carryover fish stocked at 2,000 fish/ac; all ponds were restocked with 5-inch fingerlings (6,000/ac) in the spring of the second year.  In the first study, more efficient grading (14% fewer under-sized fish sent to processing plant with the UAPB grader) resulted in faster growth of fingerling and carryover fish.    More frequent grading and harvesting removed market-size fish faster and prevented carryover fish from becoming out-of-size.

Feed mills adopted new feed formulations in 2008 in response to record high feed prices.  This study compared survival, growth, FCR and net yield of four recently developed commercially available channel catfish diets in a multiple-batch production scenario.  Sixteen 0.1-ha ponds were stocked 8 May 2008 with 14,388 fingerlings/ha (12.5 cm) and 4,308 head/ha (350 g) of carryover fish.  The feeds used in this study were: 1) 32% corn gluten feed, 2) 32% premium feed, 3) 32% standard feed, and 4) 24% premium feed.  Each of the feed treatments was assigned randomly to four ponds.  At harvest (23-26 September 2008), the net yield of carryover fish fed varied significantly with the diet fed with the greatest yield from the 32% premium diet followed in descending order by the 32% standard, the 32% corn gluten, and the 24% premium diet.  The 32% premium and 32% standard feed treatments had similar FCR’s that were significantly lower than the FCR’s of the 32% corn gluten feed and the 24% premium feed.  There was no difference in shank fillet yield among treatments but the catfish fed 32% corn gluten feed had significantly less visceral fat.  A partial budget analysis compared switching to the 32% standard or 32% corn gluten feed from 32% premium.  The higher yield from 32% premium feed more than offset its higher cost.  It was more profitable to feed the more expensive 32% premium feed.

Artificial spawning and out of season spawning in catfish are techniques being explored to enhance the production of hybrid catfish (blue catfish- channel catfish) fingerlings. Experiments conducted in 2008 in indoor wet laboratory facilities at UAPB evaluated different patterns of water temperature increase to advance the spawning season in female channel catfish.  Plasma samples were collected during the course of this experimentation and assayed for steroid hormones.  Lipid and fatty acid analyses were performed on the plasma and fertilized eggs of the different treatment groups.  Analyses of these data are underway.  Fertilized eggs were incubated to assess fry survival.  Preliminary inspection of the fry survival data revealed that embryos produced by female catfish accelerated towards spawning by artificially increasing spring water temperatures did not perform as well those from fish held within a natural rate of spring water temperature increase.  Greater care in managing the entire annual reproductive cycle rather than only the final months before spawning is warranted to better advance the spawning season in channel catfish.  Field trials performed on a commercial catfish hatchery compared the same dose of carp pituitary and catfish pituitary extracts and revealed that catfish pituitary extract performed as well or was superior to carp pituitary extract at inducing ovulation in channel catfish. 

A 13-week trial was conducted using channel catfish fingerlings (initial mean weight of 61.4 g/fish ± 1.5 g SD) at a temperature of 16^o C in three separate recirculating systems, each consisting of four 1140-L tanks. Each diet was made using a commercially available 32%- protein pelleted basal diet, ground to 1mm and repelleted into a sinking feed with the addition of 2% soybean oil (control - SBO), 2% flaxseed oil (FLAX), or 2% soybean oil and 2% dairy-yeast prebiotic (PREB). Fish were fed once daily to apparent satiation. Fish fed FLAX had a lower FCR, compared to the other two diets. Fish fed FLAX and PREB diets had higher weight gain and feed consumption than the SBO diet. Lysozyme activity and mean corpuscular hemoglobin content (MCHC) was also higher in FLAX and PREB diets. FLAX fed fish had an increased Hepatosomatic index (HSI) compared to SBO and PREB.

We determined the effects of four diets (36% protein, 10% supplemental lipid) differing in protein and/or lipid source on egg and fry production in channel catfish. Diets included (1; control) fish meal, poultry by-product meal, and 10% menhaden fish oil ( FM-PBM-FO ), (2) fish meal, poultry by-product meal, 5% menhaden fish oil, and 5% poultry fat ( FM-PBM-FO-PF ), (3) poultry by-product meal and 10% menhaden fish oil (PBM-FO), or (4) all plant protein sources and 10% menhaden fish oil (PP-FO). There were no differences in brood mortality among treatments. Fish fed the FM-PBM-FO-PF diet had greater spawning success, fecundity, egg mass weight, and hatch rates than fish fed PP-FO, but most parameters were not different from the control or PBM-FO diet. There were no protein x lipid source interactions for any parameter between the control and FM-PBM-FO-PF diets, indicating that poultry fat can partially replace fish oil in catfish broodstock diets with a variety of animal and plant protein sources. Fish fed diets containing FM and PBM (in addition to plant proteins) produced more eggs than fish fed only PBM or PP.

We conducted a feeding trial to determine the effects of Grobiotic-A, a dairy/yeast prebiotic, on channel catfish fingerlings (3.2 + 0.004 g initially). The basal diet was a commercially available 36%-protein extruded pellet with 2% cellulose (control) or prebiotic. Each diet was fed to groups of 20 channel catfish fingerlings stocked in each of five replicate 110-L tanks per treatment in a flow-through system once daily to satiation. The trial is still in progress until virulent cultures of ESC can be obtained for a bacterial challenge, but so far there has been no difference in average individual weight gain or survival between treatments.  

Sweet potato tops are currently an underutilized part of the sweet potato plant. Channel catfish fingerlings (initial individual weight ((mean+SE)) =16.1 + 0.08g) were stocked at 15 fish per tank in each of 4 tanks per diet and fed one of 3 diets once daily to satiation for 10.5 weeks. Diets contained zero, 11.5% or 23% sweet potato tops (SPT) meal produced by lyophilizing chopped sweet potato leaves and grinding the frozen product to a fine powder. The SPT meal was increased at the expense of wheat midds to maintain all diets similar in total protein (31-32%) and energy content. Weight gain, survival, alternative complement activity and lysozyme activity did not differ by diet, indicating that meal made from sweet potato tops is a suitable ingredient for inclusion in practical diets for channel catfish up to the maximum level tested (23%). Although hematocrit was depressed in fish fed diets with 11.5 or 23% SPT relative to the control diet without SPT, all of the hematocrit values were within the normal range for healthy catfish. 

Fingerling channel catfish ((mean+SE)) =16.1 + 0.08g in tanks were fed diets with 32% total protein including animal protein supplied either by poultry by-product meal or from Alaskan Pollack visceral meal (APVM; 0 or 4% of diet). After 10.5 weeks there were no differences in weight gain, survival, or non-specific immune responses between treatments. Fatty acid composition of fillets is in progress to determine if the APVM can increase the n-3 fatty acid concentration of the product as well as more limited marine protein and lipid sources (e.g., menhaden fish meal and oil).

An 8-week feeding trial was conducted in tanks with fingerling channel catfish fed diets with 32% protein (premium, standard, or corn-gluten-feed versions) or 24% protein (premium formula). Fish were fed once daily to satiation and weighed every two weeks to track growth. There were no differences in weight gain or survival by treatment, but feed conversion was significantly higher (worse) in fish fed the 24%-protein diet. Results for fingerlings were similar to those for carryover fish in a pond study with fish fed similar diets.  

Sampling for cool-weather off-flavor algae and associated conditions was performed on a weekly basis from December-May on four, southeast Arkansas commercial catfish farms and in 3 production ponds on each farm. The off-flavor algae encountered were Anabaena circinalis, followed by Pseudanabaena spp. In 06-07, off-flavor algae were present in 6.9% of samples, with highest incidence during  January (13.3%) and highest concentrations of algae during April (6% of ponds with over 1000 filaments/ml). In 07-08, the overall incidence was 22.2%, with monthly incidence and abundance incidences similar. In 07-08, water samples with levels exceeding 1000 filaments/ml had at times an earthy odor, caused by geosmin. Continued monthly sampling during the summer (May-Oct.) found average incidences of 37.7% and 43.8% in 07 and 08 with highest abundance incidences in Aug. (37.5% and 50%). Although off-flavor algae presence and abundance incidence was lower in the winter than summer, winter occurrences were more variable and still substantial.