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Six 0.1‐ha earthen ponds with 45 kW/ha of aeration capacity were stocked with hybrid catfish (Ictalurus punctatus x I. furcatus) ranging from 15,000 to 90,000 fish ha−1 in 15,000 fish ha−1 increments to analyze the effect of nitrogen loading on ammonia accumulation and fish production. Minimum dissolved oxygen (DO) concentration was maintained above 3.0 mg O2 L−1 to prevent hypoxia‐induced appetite reduction. Stocking density did not impact survival but decreased average fish harvest weight and increased food conversion ratio (FCR). Gross production increased with stocking density and ranged from 7249 to 35,674 kg ha−1. Average total (TAN) and un‐ionized ammonia (NH3) were not different among stocking densities despite greater nitrogen inputs in ponds with higher feeding rates. Nitrite (NO2−) and nitrate (NO3−) concentrations were significantly higher in ponds with higher stocking densities, suggesting that nitrification increased with nitrogen loading. Phytoplankton assimilation of ammonia is the primary ammonia removal process in traditional catfish ponds with modest fish densities and feeding rates. However, in intensively aerated ponds with high feeding rates, nitrification can become an important process for ammonia removal. These data indicate that small earthen hybrid catfish ponds with high aeration capacities can increase catfish production without ammonia accumulating. [ABSTRACT FROM AUTHOR]

Lapillus otoliths and several preparations of pectoral fin spines have been used to age Blue Catfish Ictalurus furcatus; however, there are limited studies examining relative precision of age estimates. Further, comparisons of population characteristics (e.g., growth, mortality) resulting from age structure evaluations are needed to help fisheries managers balance resources needed to conduct investigations with quality of subsequent data. We examined sectioned Blue Catfish lapillus otoliths and sectioned pectoral spine articulating processes, basal recesses, and articulating surfaces to compare relative precision of age estimates. Additionally, dynamic rate functions and resulting population models were examined to determine if variation in age estimates resulted in divergent interpretation of population characteristics. Generally, aging precision was greatest for articulating surface and lapillus otolith sections. Although growth models generated from each aging structured differed, mortality estimates and conclusions drawn from harvest-regulated population modeling were similar across structures. These results demonstrate that although there is variability in precision and growth modeling among different Blue Catfish aging structures, estimates for key population parameters remain consistent. [ABSTRACT FROM AUTHOR]

Systematic descriptions of North American Miocene freshwater fishes are extremely uncommon, with those from the Gulf Coastal Plain region being completely absent. In this study we examined 324 historically collected freshwater fish elements derived from the late Miocene (Hemphillian) Mauvilla fossil site located in Mobile County, Alabama, USA. Analysis of these elements confirmed the presence of three unequivocal taxa including Atractosteus sp. cf. A. spatula, Ictalurus spp., and Aplodinotus grunninens. The preserved elements consisted of spines, pharyngeal bones, pharyngeal teeth, and scales, likely indicating a taphonomic bias towards large individuals with robust elements. The co-occurrence of these three taxa indicate they were derived from a medium-to-large river fish assemblage, suggesting that one or more of the rivers that constitute the nearby Mobile Basin may have been present in the region during the late Miocene. Molecular divergence estimates and morphological similarity to modern representatives both support the presence of these extant taxa in the late Miocene, and the examined remains represent some of the earliest fossil occurrences of these extant taxa. These three taxa also represent the first biogeographic occurrence of each in the late Miocene of both Alabama and the Gulf Coastal Plain of North America and helps to improve our understanding of Miocene freshwater fish assemblages. [ABSTRACT FROM AUTHOR]

The life‐history traits and population dynamics of the black bullhead Ameiurus melas (Rafinesque) were studied monthly from August 2009 to December 2012 in Lake Sava in Belgrade (Serbia). This period included a mass mortality event in May 2011 and subsequent population recovery during 2012. Available evidence suggests the mass mortality was caused by European catfish virus that only affected the black bullhead. Changes in key life‐history traits and the recovery potential (increase in catch‐per‐unit‐effort, doubling of young‐of‐the‐year to adult ratio, earlier maturation and increased fecundity) following the mass mortality event suggest population resilience typical of a recurring boom‐bust pattern and demonstrate the species' capacity to recover rapidly and re‐establish following disturbance. Repeated systematic mass removals of both juveniles and adults (using fyke nets) will be required if future fishery management measures aimed at limiting the population size are to be effective. [ABSTRACT FROM AUTHOR]

In 2009, a virulent strain of Aeromonas hydrophila caused severe disease and high mortalities (motile aeromonad septicemia variant [MASv]) in farmed channel catfish (Ictalurus punctatus) and hybrid catfish (I. punctatus × I. furcatus) in eastern Mississippi and Alabama. As is common in MAS, there is severe hemorrhagic dermatitis with ulceration, as well as abdominal hyperemia, petechiation, and mild ascites. Additional findings in MASv cases include panophthalmitis and orbital cellulitis, leading to ocular rupture, and brains are often hyperemic with mild random acute hemorrhage. In MASv infections, there is consistently also marked hemorrhage and edema in the submucosa and muscularis of the stomach, with lymphangitis and a few bacteria, plus splenomegaly with infarcts. Microscopically, spleens have necrosis of ellipsoids with macrophage infiltration and small numbers of bacteria; however, large infarcts are filled with bacteria. Other organs, such as liver, kidneys, and intestine, which are typically associated with MAS caused by various aeromonad species, are less affected. The findings in the stomach have not been reported in MAS in farmed catfish, to our knowledge, and the splenic changes are highly characteristic of MAS compared to infection with other gram-negative bacteria, including Edwardsiella ictaluri and other aeromonad species and strains. [ABSTRACT FROM AUTHOR]

Alternative management strategies will be required to produce hybrid catfish (♂Ictalurus punctatusX ♀Ictalurus furcatus) year-round to provide continuous market supply. Hybrid catfish fingerlings were stocked at 9,880 head/ha singly or in co-culture with sub-marketable (mean weight = 454 ± 16 g) hybrid catfish carried over the winter from a previous year’s multi-size trial. Economic analyses compared cost of production ($/kg of market-size fish produced) and cash flow of single- and multiple-batch production of hybrid catfish for a single- and two-year period. Gross total and marketable yields were significantly greater in the mixed-size treatment as compared to the single-size treatment, in spite of the significantly greater percentage of market-size fish (84%) in the single-size treatment than in the mixed-size treatment (71%). Cost of production ($/kg) was 4% to 10% lower in the multi-size treatment in the single-year analysis, but 18% to 20% lower when the full two-year cycle was assessed. Cash flow and cash flow risk were improved substantially with the multi-size treatment primarily because the overwintered sub-market-size fish from the previous year reached market size three to four months earlier than in the single-size treatment. [ABSTRACT FROM PUBLISHER]

Background: Versive seizure characterized by conjugate eye movement during epileptic seizure has been considered commonly as one of the most valuable semiological signs for epilepsy localization, especially for frontal lobe epilepsy. However, the lateralizing and localizing significance of ictaleye deviation has been questioned by clinical observation of a series of focal epilepsy studies, including frontal, central, temporal, parietal and occipital epilepsy.Case Presentation: Two epileptic cases characterized by ipsiversive eye deviation as initial clinical sign during the habitual epileptic seizures are presented in this paper. The localization of the epileptogenic zone of both of the cases has been confirmed as inferioposterior temporal region by the findings of ictalstereoelectroencephalography (SEEG) and a good result after epileptic surgery. Detailed analysis of the exact position of the key contacts of the SEEG electrodes identified the overlap between the location of the epileptogenic zone and human MT/MST complex, which play a crucial role in the control of smooth pursuit eye movement.Conclusion: Ipsiversive eye deviation could be the initial clinical sign of inferioposterior temporal lobe epilepsy and attribute to the involvement of human MT/MST complex, especially human MST whichwas located on the anterior/dorsal bank of the anterior occipital sulcus (AOS). [ABSTRACT FROM AUTHOR]

The article presents a study which described polymorphic single nucleotide polymorphism (SNP) markers in growth-related genes of the channel catfish Ictalurus punctatus found in various parts of the U.S. between 1997 and 2004. The variables considered include estimated breeding values of base population of the sample specimens, breeding procedure followed, and genetic preservation. The use of polymerse chain reaction (PCR) in gene amplification is discussed.

Commercial production of hybrid catfish (female channel catfish Ictalurus punctatus × male blue catfish Ictalurus furcatus) is reliant on interdependent biological, environmental, and technical procedures. This study addresses one of these critical components - the evaluation of channel catfish ovarian development based on sonographic analysis. The objectives were to: (1) develop a channel catfish ovarian ultrasonography index, (2) test the effect of the spawning trials on fertilization estimates of fish assessed using the ultrasonography index, and (3) evaluate the expected (hypothesized) and observed outcome of the ultrasonography assessments. Seven ovarian morphology classifications were developed based on ultrasonography of 915 channel catfish ( N = 915 images), and 210 females were selected for spawning. The predictions based on the classifications prior to hormone injection showed a significant effect ( P < 0.002) on the observed outcomes (viable or nonviable eggs). The probability of correct classification was 0.86-0.89 for Categories 3 (developing), 4 (advanced), and 5 (mature), and 0.93-1.0 for Categories 1 (undeveloped), 2 (underdeveloped), 6 (spawned), and 7 (atretic). The ultrasonography index covered the full range of ovarian dynamics (i.e., recrudescence through spawning). It provided an unobtrusive, direct method of ovarian assessment to work toward improving the efficiency of broodstock selection. [ABSTRACT FROM AUTHOR]

A study was conducted to examine the efficacy of crystalline lysine in alternative diets for pond-raised hybrid catfish, ♀ Ictalurus punctatus × ♂ Ictalurus furcatus. Two 28% protein alternative diets supplemented with l-lysine HCl at the required level based on 62% (previously published value) or 100% lysine availability were compared with a traditional 28% protein control diet. Hybrid catfish fingerlings (mean initial weight = 43 g/fish) were stocked into 15 earthen ponds (0.04 ha) at a density of 14,826 fish/ha with five ponds per treatment. Fish were fed once daily to apparent satiation for a 173-d growing season. There were no significant differences in total diet fed, net yield, weight gain, and survival among dietary treatments. There were also no significant differences in carcass yield, fillet yield, and fillet proximate composition and fillet lysine concentration among treatments. Fish fed the traditional control diet had slightly, but significantly, lower feed conversion ratio than fish fed alternative diets, which is likely related to higher dietary fiber levels in the alternative diets. Results from this study show that crystalline lysine can be considered 100% available when used to supplement lysine-deficient diets for pond-raised hybrid catfish. [ABSTRACT FROM AUTHOR]

There has been considerable interest worldwide in applying bacterial inocula to channel catfish ponds for improving water quality, especially for acceleration of ammonia nitrogen oxidation through bacterial nitrification. The effects of a selected bacterial amendment on water quality in small research ponds for channel catfish production were evaluated at the E. W. Shell Fisheries Center, Auburn University, Auburn, Alabama. Three ponds were treated with the bacterial amendment Waste & Sludge Reducer™ (Keeton Industries, Wellington, CO, USA) at three times the dose recommended by the manufacturer every 2 wk, and three ponds served as controls. There were nonconsistent minor differences in water quality between ponds treated with a commercial bacterial amendment and control ponds on several sampling dates. However, the average concentrations of water quality variables did not differ ( P > 0.05) between the treatments and control. Channel catfish yield was not improved by applying the bacterial amendment. This study demonstrates that the bacterial amendment was of no benefit in improving water quality in well-managed catfish ponds where stocking rates, feeding rates, and amount of aeration are balanced. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Fisheries & Aquatic Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The channel catfish Ictalurus punctatus is a known host for 10 species of Henneguya, but few other myxozoan genera are described from this species. Unicauda is a genus of myxozoan parasites within the family Myxobolidae that consists of 10 valid species from freshwater fish. Herein, we describe a novel species of Unicauda from the intestinal tract of farm-raised channel catfish in Mississippi. Myxospores were consistent with the genus Unicauda but exhibited a unique branching at the terminal end of the caudal process that has not previously been reported. Myxospores measured 90.39 ± 14.97 μm (mean ± SD; range = 70.88-126.02 μm) in total length. The spherical spore body measured 7.31 ± 0.26 μm (6.75-7.84 μm) in length and 7.01 ± 0.63 μm (6.1-8.01 μm) in width. The 2 polar capsules measured 3.45 ± 0.33 μm (3.02-4.03 μm) in length and 2.65 ± 0.32 μm (2.18-3.11 μm) in width. The single caudal process measured 82.98 ± 14.97 μm (63.39-118.63 μm) in length from the base of the spore body to the end of the most terminal projection. Terminal projections measured 26.83 ± 8.8 μm (12.34-42.29 μm) in length and 0.95 ± 0.23 μm (0.52-1.6 μm) in width. The 18S rRNA gene sequence obtained did not match any published sequences. Given the uniqueness of the myxospore morphology, histological presentation, and gene sequence data, we describe this as an unreported species, Unicauda fimbrethilae n. sp. [ABSTRACT FROM AUTHOR]

Recent studies with rainbow trout, Oncorhynchus mykiss, demonstrated that grain distiller's dried yeast ( GDDY) at up to 12% inclusion was an effective dietary protein source when replacing fish meal. To examine the effectiveness of GDDY when replacing an increased variety of dietary protein sources, two feeding trials were conducted. In the first trial, six commercial-type diets were formulated to contain 42% digestible protein and 20% crude lipid with GDDY included at 0, 6, 9, 12, 15, and 18% to replace all dietary protein sources except fish meal. In the second trial, four plant-based diets with GDDY at 0, 9, 12, and 15% were examined. Experimental diets were fed twice daily, to apparent satiation, to three replicate tanks of fish/diet (initial weight = 22.3 ± 0.7 g) for 10 wk in a 15 C recirculating system. Results demonstrated excellent fish growth and the inclusion rate of GDDY did not negatively affect growth or feed conversion. No significant negative effects of GDDY on body indices or whole-body proximate composition were observed. Based on these results, GDDY can be included in both commercial-type diets and plant-based diets for rainbow trout at up to 18 or 15%, respectively, without decreasing growth performance. [ABSTRACT FROM AUTHOR]

Native fish faunas throughout the American Southwest have declined dramatically in the past century, mainly a consequence of habitat alteration and alien species introductions. We initiated this 6-year study to evaluate the efficacy of mechanical removal of nonnative predaceous rainbow trout Oncorhynchus mykiss, brown trout Salmo trutta, yellow bullhead Ameiurus natalis and smallmouth bass Micropterus dolomieu from an open 4.6-km reach of West Fork Gila River in southwest New Mexico, USA. Removal efforts involved intensive sampling with a 10- to 12-person crew using backpack electrofishers and seines to capture fish over a 4- to 5-day period each year. Additionally, two reference sites were sampled with similar methods to compare temporal changes in species mass in the absence of a removal effort. Results were mixed. Mass of yellow bullhead, rainbow trout and brown trout declined in the removal reach from 2007 through 2012, but there was no change in smallmouth bass. Concurrently, mass of Rainbow trout, yellow bullhead and smallmouth bass did not change at reference sites, but brown trout mass declined, indicating factors other than removal were driving abundance of brown trout. Occurrence of several large flathead catfish Pylodictis olivaris in the removal reach in 2012 changed what would have been a decline in overall nonnative mass to no change over the course of the study. Spikedace Meda fulgida was the only native species positively responding to predator removal. Results of this study suggest that with moderate effort and resources applied systematically, mechanical removal can benefit some native fish species, but movement of problem species from surrounding areas into removal reaches necessitates continued control efforts. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The actinospore diversity of infected Dero digitata was surveyed (May 2011) from a channel catfish ( Ictalurus punctatus) production pond in the Mississippi Delta region for the elucidation of unknown myxozoan life cycles. At present, only 2 myxozoan life cycles have been molecularly confirmed in channel catfish, linking the actinospore stage from an aquatic oligochaete ( D. digitata) and the myxospore stage from the catfish. In this study D. digitata (n = 2,592) were isolated from oligochaetes collected from the bottom sediment of a channel catfish production pond. After 1 wk of daily observation, a total of 6 genetically different actinospore types were observed. The collective groups were classified as 2 aurantiactinomyxons, 2 helioactinomyxons, 1 raabeia, and 1 triactinomyxon. Overall prevalence of myxozoan infections in the isolated oligochaetes was 4.4%. Actinospores were photographed and measured for morphological characterization. Four previously undescribed actinospore types were identified and characterized molecularly and morphologically. Phylogenetic analysis revealed the raabeia and one of the helioactinomyxon (type 1) actinospores were closely related to the group of myxozoans known to parasitize ictalurids in North America. To date, no myxospores have been linked to the newly sequenced actinospores reported in this survey. The morphological and molecular data generated from this study will assist in the identification of myxospore counterparts for these actinospore stages and aid in the elucidation of unknown myxozoan life cycles in closed production systems. [ABSTRACT FROM AUTHOR]

Domestication and selection for important performance traits can impact the genome, which is most often reflected by reduced heterozygosity in and surrounding genes related to traits affected by selection. In this study, analysis of the genomic impact caused by domestication and artificial selection was conducted by investigating the signatures of selection using single nucleotide polymorphisms (SNPs) in channel catfish (Ictalurus punctatus). A total of 8.4 million candidate SNPs were identified by using next generation sequencing. On average, the channel catfish genome harbors one SNP per 116 bp. Approximately 6.6 million, 5.3 million, 4.9 million, 7.1 million and 6.7 million SNPs were detected in the Marion, Thompson, USDA103, Hatchery strain, and wild population, respectively. The allele frequencies of 407,861 SNPs differed significantly between the domestic and wild populations. With these SNPs, 23 genomic regions with putative selective sweeps were identified that included 11 genes. Although the function for the majority of the genes remain unknown in catfish, several genes with known function related to aquaculture performance traits were included in the regions with selective sweeps. These included hypoxia-inducible factor 1β· HIFιβ ¨ and the transporter gene ATP-binding cassette sub-family B member 5 (ABCB5). HIFβ· is important for response to hypoxia and tolerance to low oxygen levels is a critical aquaculture trait. The large numbers of SNPs identified from this study are valuable for the development of high-density SNP arrays for genetic and genomic studies of performance traits in catfish. [ABSTRACT FROM AUTHOR]

Copyright of Fisheries is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article presents information on chemotactic activity of channel catfish, Ictalurus punctatus (Rafinesque), recombinant cyclophilin A (CyPA). CyPA, a member of the highly conserved immunophilin superfamily, is widespread. It was first found as an intracellular receptor for the potent immunosuppressant cyclosporine A.

Background The freshwater sculpins (genus Cottus) are small, bottom-living fishes widely distributed in North America and Europe. The taxonomy of European species has remained unresolved for a long time due to the overlap of morphological characters. Sound production has already been documented in some cottid representatives, with sounds being involved in courtship and agonistic interactions. Although the movements associated with sound production have been observed, the underlying mechanism remains incomplete. Here, we focus on two closely related species from Belgium: C. rhenanus and C. perifretum. This study aims 1) to record and to compare acoustic communication in both species, 2) to give further insight into the sound-producing mechanism and 3) to look for new morphological traits allowing species differentiation. Results Both Cottus species produce multiple-pulsed agonistic sounds using a similar acoustic pattern: the first interpulse duration is always longer, making the first pulse unit distinct from the others. Recording sound production and hearing abilities showed a clear relationship between the sound spectra and auditory thresholds in both species: the peak frequencies of calls are around 150 Hz, which corresponds to their best hearing sensitivity. However, it appears that these fishes could not hear acoustic signals produced by conspecifics in their noisy habitat considering their hearing threshold expressed as sound pressure (∼ 125 dB re 1 μPa). High-speed video recordings highlighted that each sound is produced during a complete back and forth movement of the pectoral girdle. Conclusions Both Cottus species use an acoustic pattern that remained conserved during species diversification. Surprisingly, calls do not seem to have a communicative function. On the other hand, fish could detect substrate vibrations resulting from movements carried out during sound production. Similarities in temporal and spectral characteristics also suggest that both species share a common sound-producing mechanism, likely based on pectoral girdle vibrations. From a morphological point of view, only the shape of the spinelike scales covering the body allows species differentiation. [ABSTRACT FROM AUTHOR]

This research was designed to produce a standardized set of microsatellite loci for parentage and kinship analyses in channel catfish, the leading species of US aquaculture. Three panels of five to six markers each were developed that contained a total of two dinucleotide-, eight trinucleotide- and seven tetranucleotide-microsatellite loci respectively. The loci had a range of nine to 31 alleles per locus in an outbred population. Based on the allele frequencies measured in commercial randomly bred broodstock, the combined probability of non-exclusion of an unrelated candidate parent pair was 5.36e-18. The combined probability of non-exclusion of unrelated identical genotypes was 2.58e-08. The microsatellite panels were validated by parentage and kinship evaluation in three populations. A total of 697 spawns were collected from matings of outbred broodstock over three spawning seasons, and parents were determined unambiguously for all but three spawns. Genotype analysis also enabled the identification of half-sibling and full-sibling families produced by pond spawning. In a second experiment, parentage was unambiguously determined in nine spawns from a population consisting of broodstock derived from only four families. A third experiment demonstrated that all but one of 374 individuals from 10 full-sibling families could be assigned to a family after coculture in an earthen pond for 1 year. The standardized microsatellite panels enable the development of pedigreed catfish populations and large-scale performance evaluations in common environments to support the genetic improvement of cultured catfish through selective breeding. [ABSTRACT FROM AUTHOR]

Mosquitofish, Gambusia sp., have been spread throughout the world to biologically control mosquitoes. However, the fish has gained a reputation as an invasive species and has been implicated in displacing native aquatic species. Gambusia affinis are native to the southeastern United States and commonly occur in commercial channel catfish, Ictalurus punctatus, production ponds. We investigated effects of mosquitofish presence on zooplankton populations, water quality, disease occurrence, and fish production in experimental ponds. There were no differences between ponds with or without mosquitofish in numbers of calanoid copepods, cyclopoid copepods, total copepods, Bosmina sp., Ceriodaphnia sp., Moina sp., Daphnia sp., or total cladocerans. There were also no differences in copepod and cladoceran sizes. Copepod nauplii were more numerous during the summer months in ponds with mosquitofish. There were no differences in water quality variables (soluble reactive phosphorus, nitrate, nitrite, ammonia, total nitrogen, total phosphorus, pH) or phytoplankton density between ponds stocked with and without mosquitofish. Catfish production and disease occurrence were also similar between ponds with and without mosquitofish. Although mosquitofish may cause problems when stocked outside their native range, there does not appear to be any adverse effects of mosquitofish presence in catfish production ponds. [ABSTRACT FROM AUTHOR]

An unidentified xiphidio-type cercaria, previously thought inconsequential to catfish health, was found to be released from marsh rams-horn snails (Planorbella trivolvis) inhabiting ponds on a commercial catfish operation in the Mississippi Delta. A preliminary challenge of cohabiting channel catfish (Ictalurus punctatus) with snails actively shedding the unidentified cercariae resulted in death of some fish. A second cohabitation trial yielded similar results, as did a third challenge of 250 cercariae/fish. Histopathology revealed developing metacercariae concentrated in the cranial region, especially within the branchial chamber, with several metacercariae at the base of the branchial arches within, or adjacent to, blood vessels, possibly the proximate cause of death. Genetic sequence analysis of the 18S small subunit ribosomal DNA (ssDNA), 28S large subunit rDNA (lsDNA), and cytochrome oxidase (Cox1) genes all matched the cercariae to Drepanocephalus spathans (Digenea: Echinostomatidae), a parasite of the double- crested cormorant (Phalacrocorax auritus), a piscivorous bird endemic on most catfish farms. This is the first commentary regarding pathology of D. spathans in juvenile channel catfish as well as the first report of the marsh rams-horn snail as an intermediate host in the D. spathans life cycle. The data presented here suggest this parasite could have limiting effects on catfish production, further supporting the need for adequate snail control programs to reduce trematode prevalence on commercial catfish operations. [ABSTRACT FROM AUTHOR]

The present study was designed to determine the optimal level of calcium hardness in hatching waters to incubate channel catfish Ictalurus punctatus × blue catfish I. furcatus hybrid catfish eggs. Hatching success of hybrid catfish eggs was higher (P < 0.05) at a calcium hardness (CaCO3) of 75 mg/L in hatching waters than at a calcium hardness of 25 or 50 mg/L; however, further increases in calcium concentration did not improve hatching success. A minimum water hardness of CaCO3 at 75 mg/L is recommended for incubating hybrid catfish eggs. Received September 13, 2011; accepted November 22, 2011 [ABSTRACT FROM AUTHOR]

Edwardsiella bacteria are leading fish pathogens causing huge losses to aquaculture industries worldwide. E. tarda is a broad-host range pathogen that infects more than 20 species of fish and other animals including humans while E. ictaluri is host-adapted to channel catfish causing enteric septicemia of catfish (ESC). Thus, these two species consist of a useful comparative system for studying the intricacies of pathogen evolution. Here we present for the first time the phylogenomic comparisons of 8 genomes of E. tarda and E. ictaluri isolates. Genome-based phylogenetic analysis revealed that E. tarda could be separate into two kinds of genotypes (genotype I, EdwGI and genotype II, EdwGII) based on the sequence similarity. E. tarda strains of EdwGI were clustered together with the E. ictaluri lineage and showed low sequence conservation to E. tarda strains of EdwGII. Multilocus sequence analysis (MLSA) of 48 distinct Edwardsiella strains also supports the new taxonomic relationship of the lineages. We identified the type III and VI secretion systems (T3SS and T6SS) as well as iron scavenging related genes that fulfilled the criteria of a key evolutionary factor likely facilitating the virulence evolution and adaptation to a broad range of hosts in EdwGI E. tarda. The surface structure-related genes may underlie the adaptive evolution of E. ictaluri in the host specification processes. Virulence and competition assays of the null mutants of the representative genes experimentally confirmed their contributive roles in the evolution/niche adaptive processes. We also reconstructed the hypothetical evolutionary pathway to highlight the virulence evolution and niche adaptation mechanisms of Edwardsiella. This study may facilitate the development of diagnostics, vaccines, and therapeutics for this under-studied pathogen. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study addresses rapid methods to identify mature channel catfish, Ictalurus punctatus, females for induced spawning with luteinizing hormone releasing hormone analog (LHRHa) and common carp pituitary extract (CPE) and the effects of stage of maturity, hormone dose, season, and cannulation before hormone injection. Hormonal intervention is the most effective method for inducing maturation and spawning in channel catfish × blue catfish, Ictalurus furcatus, hybrids. A total of 80 mature channel catfish were staged for maturity based on secondary sexual characteristics and 20-30 oocytes cannulated to ascertain their maturation stage based on the position of gonadal vesicle. Twenty females were randomly assigned to one of the four hormone regimes (priming + resolving dose): CPE 2 + 8 mg/kg (CPEC); LHRHa 20 + 40 µg/kg (LHRHaL); LHRHa 20 + 60 µg/kg (LHRHaM); and LHRHa 20 + 80 µg/kg (LHRHaH) and a fifth treatment consisted of 20 females selected based on apparent maturity as evidenced by external appearance were injected with CPE, 2 + 8 mg/kg without cannulation (CPEO). Two trials were conducted in early part of the spawning season and two trials in peak season. External methods to identify maturity correlated ( r = 0.63) with that of 'germinal vesicle position' method to identify the stage of maturity in females. Mean percent of females that ovulated, hatched, and fry produced per kg body weight did not differ ( P > 0.05) among the five hormone treatments. The mean percent females that ovulated was higher ( P < 0.05) for CPE-induced females that were identified as 'excellent' females based on external examination. The performance of cannulated females did not differ ( P > 0.05) with that of non-cannulated catfish. The mean egg quality of hormone-induced females and percent of females ovulated in response to hormone treatment established a weak but significant linear relationship ( Y = 3.85 + 0.008 × ovulation, r2 = 0.39, P < 0.05). [ABSTRACT FROM AUTHOR]

lloglossidium fonti sp. nov. is described based on specimens from black bullheads ( Ameiurus melas) collected from several localities in northwestern Minnesota. The new species is morphologically closest to A. corti and A. geminum. These two species were also found in the same region as A. fonti sp. nov. and sometimes in the same individual fish. Examination of numerous genetically marked specimens has demonstrated that the most reliable distinguishing feature among the three species is the position of anterior margin of the vitelline fields. In the new species they are situated at the level of anterior margin of ventral sucker while in A. corti it is at the level of intestinal bifurcation or even further anteriorly, and in A. geminum it is at the level of posterior margin of ventral sucker or further posteriorly. The new species has a relatively smaller cirrus sac than A. geminum. Despite rather minor, albeit stable morphological differences, the molecular data strongly supported the status of A. fonti sp. nov. as a new species. Moreover, molecular data and morphological examination of new material suggested that A. kenti, earlier synonymized with A. corti, is a valid species that is resurrected here. Comparison of 2420 base long sequences of nuclear rDNA (partial 18S, complete ITS region, and partial 28S) obtained from multiple specimens of all 4 species collected in Minnesota, North Dakota, Nebraska and Mississippi, showed essentially no intraspecific variability (except for 1 base difference in the ITS2 region of A. fonti sp. nov.), but has demonstrated pronounced interspecific differences. The new species was not found in the four examined catfish species from the Red River of the North (on the border between North Dakota and Minnesota) and neighbouring North Dakota. [ABSTRACT FROM AUTHOR]

This study demonstrated the feasibility of producing soluble protein (CFSP) and insoluble protein (CFISP) fractions from catfish muscle protein. CFSP and CFISP contained 60.6% and 73.8% protein and 8.6% and 20.3% fat, respectively. Both CFSP and CFISP contained essential amino acids. Differences were observed between physicochemical properties of the 2 protein fractions, including nitrogen solubility, emulsion stability, and fat adsorption capacity. The flow and viscoelastic properties of the emulsions prepared with CFSP and CFISP were investigated using a rheometer. The power law model and the Casson model were used to determine the flow behavior index ( n), consistency index ( K), and yield stress. Emulsion containing CFSP (ECFSP) had a higher K value than emulsion containing CFISP (ECFISP). Both ECFSP and ECFISP emulsions exhibited pseudoplastic behavior and viscoelastic characteristics. The G′ (an elastic or storage modulus) and G″ (a viscous or loss modulus) values for ECFSP were higher than ECFISP. Catfish muscle tissue can be easily separated into soluble and insoluble protein powders that have desirable functional properties. [ABSTRACT FROM AUTHOR]

Channel catfish ( Ictalurus punctatus) muscle was subjected to 6 protein extraction and precipitation techniques using acid solubilization (pH 2.0, 2.5, and 3.0) or alkaline solubilization (pH 10.5, 11.0, 11.5) followed by precipitation at pH 5.5. The catfish protein isolate was compared with ground defatted white muscle. Alkali-processed catfish showed increased gel rigidity, gel strength, and gel flexibility compared to acid-processed catfish, which exhibited inconsistent functional performance, increasing and decreasing gel rigidity, gel strength, and gel flexibility. The gel rigidity ( G′) at pH 3.0 in the absence of salt had the highest G′ of the acid treatments and was not significantly different from the alkaline-treated catfish muscle ( P > 0.05). However in the presence of added salt pH treatment it had the lowest G′ and was different from alkaline treatments ( P < 0.05) during break force testing. These results show that pH-shift processing of channel catfish muscle provides highly functional isolates with a potentially broad range of applications. This range of applications is possible due to the modification of the textural properties of catfish muscle protein produced using different acidic or alkaline pH solubility treatments. [ABSTRACT FROM AUTHOR]

A study was conducted to determine the clearance time of yellow pigments lutein and zeaxanthin in channel catfish at various temperatures. Fish of initial weight of 13.4 g were stocked into flow-through aquaria and fed daily with a pigment-enhanced diet for 11 wk when yellow color became visible in the flesh. All fish were then transferred into tanks in three recirculating systems that were assigned one of the three temperatures (10, 20, and 30 C). During the pigment clearance period, fish were fed a control diet without added pigments daily to satiation for 12 wk. Every 4 wk, fish from three randomly chosen tanks per temperature were euthanized and fillets were analyzed for yellow color intensity (Commission Internationale de I'Eclairage [CIE] b*) and lutein and zeaxanthin concentrations. The b* values of fillets of fish reared at 20 and 30 C decreased linearly as time progressed. There was no significant linear regression of b* value against time for fish raised at 10 C. The rate of pigment clearance was similar for fish reared at 20 and 30 C. Results demonstrate that about 8 wk were needed for catfish to "purge most of yellow pigment at warm temperatures (20 and 30 C). A longer period of time (>12 wk) was required at 10 C. [ABSTRACT FROM AUTHOR]

Two experiments were conducted to evaluate various ingredient combinations in a 28% or 32% protein diet for optimum performance of channel catfish Ictalurus punctatus. All diets contained soybean meal and corn, but with or without cottonseed meal, wheat middlings or fish meal (FM). Channel catfish fingerlings were stocked into 0.04 ha earthen ponds at 18 530 fish ha−1. Fish were fed one of eight diets once daily to apparent satiation for two growing seasons. Results demonstrated that the dietary ingredient composition used had significant effects on fish performance, but magnitude of differences was relatively small. Overall, diets containing FM resulted in greater weight gain (Experiments 1 and 2) and lower feed conversion ratio (Experiment 1) than fish fed all-plant diets. However, certain combinations of plant ingredients provided the similar fish growth as some diets containing FM. There were no significant differences in weight gain between fish fed soybean meal–corn or soybean meal–corn–wheat middlings-based diets with cottonseed meal or FM. The use of wheat middlings in the diet had no significant effects on fish production characteristics. [ABSTRACT FROM AUTHOR]

A 2 x 2 factorial experiment was conducted to evaluate the effects of commercial diets (32% protein, 3% fat [32/3 diet] or 36% protein, 8% fat [36/8 diet]; Malick Aquafeed, Inc.) and the influence of strain (U.S. Department of Agriculture [USDA] 103 or Norris) on performance variables and mitochondrial respiratory chain enzyme activities in the liver, muscle, and intestine of channel catfish Ictalurus punctatus. Juvenile channel catfish (average weight = 29.71 and 38.79 g for USDA 103 and Norris strains, respectively) were stocked into sixteen 152-L aquaria at a density of l0 fish/aquarium. Four aquaria were used for each dietary treatment. Fish were fed twice daily to apparent satiation for 16 weeks. Results indicated that diet and strain had significant (P < 0.05) main effects on weight gain, feed consumption, feed efficiency, and specific growth rate. Diet composition had a significant main effect on condition factor, regardless of strain. There was a significant (P < 0.0007) fish strain x diet composition interaction effect on feed efficiency. Regardless of strain, fish fed the 36/8 diet formula had higher activities for respiratory enzyme complexes I, II, III, and IV in the liver, intestine, and muscle than fish fed the 32/3 diet. The main effect was significant but not consistent for complex I and IV activities in the liver and muscle and complex II activities in the liver and intestine. The fish strain x diet composition interaction effect was significant for complex I activity in the liver and for complex II and IV activities in the muscle. These data demonstrate that the USDA 103 strain of channel catfish appears to possess superior traits in growth performance compared with the Norris strain. Our data indicate that diet has an important effect on channel catfish production and that a commercial 36/8 diet produces enhanced growth performance and mitochondrial enzyme activities relative to a 32/3 diet. [ABSTRACT FROM AUTHOR]

This study was conducted to gain a better understanding of the effect of exposure to the myxozoan Henneguya ictaluri (the agent of proliferative gill disease [PGD]) on host physiology by measuring the variation in selected blood characteristics in three differently affected host taxa (channel catfish Ictalurus punctatus, blue catfish I. furcatas, and blue catfish x channel catfish hybrid fingerlings). Forty-five fish of each host taxon were exposed to PGD, mad 10 fish of each host taxon were sampled at 24, 96, and 168 h. Fish were weighed, blood was collected and analyzed for a suite of physiological variables, and wet mount preparations of gill clips were examined grossly for the presence of cartilage breaks. The results of this study are consistent with the current knowledge regarding H. ictaluri infections in blue catfish, channel catfish, and blue catfish x channel catfish hybrids. Chondrocytic lysis was observed in channel catfish and hybrid catfish at 96 and 168 h but was not observed in blue catfish. There was an observed reduction in oxygen partial pressure (pO2) and an increase in carbon dioxide partial pressure (pCO2) at 96 h in the blood of channel catfish and hybrid catfish, but these changes were not exhibited by blue catfish. For all species, pH decreased as lactate concentrations increased. The lack of physiological changes and the absence of H. ictaluri sporozoites and DNA in gill tissue lead us to speculate that H. ictaluri is unable to estabfish infection in blue catfish. Current research investigating the mechanisms of infection and portals of parasite entry into blue catfish, channel catfish, and blue catfish x channel catfish hybrids is underway to better elucidate the defenses employed by blue catfish against H. ictaluri. [ABSTRACT FROM AUTHOR]

The channel catfish Ictalurus punctatus is a popular sport fish commonly maintained by annual stocking in small impoundments. We sought to determine whether channel catfish negatively affect two other sport fishes (bluegill Lepomis macrochirus and largemouth bass Micropterus salmoides) in Alabama's state public fishing lakes (ASPF lakes) through competition or predation. Using a variety of gears, we sampled channel catfish, largemouth bass, and bluegills in 12 ASPF lakes with variable channel catfish stocking and harvest rates. Four of these lakes were sampled more intensively to quantify the diets of these three species. Bioenergetics simulations were used to predict the annual consumption of channel catfish and largemouth bass populations of average density, size structure, and growth from these impoundments. Metrics of growth, condition, abundance, and population structure were not related between species. Latitude was negatively related to channel catfish growth. The diets of channel catfish and bluegills were moderately similar across all seasons in all lakes, while those of channel catfish and largemouth bass were highly dissimilar. Within species, diet similarity was high among lakes. Bioenergetics simulations suggest that the channel catfish populations in these lakes consume relatively little fish, particularly when compared with a typical largemouth bass population. We found little evidence of negative effects of channel catfish on the bluegill and largemouth bass populations in ASPF lakes, although largemouth bass growth and condition were poorest in the lake with the highest channel catfish stocking rate. However, current stocking and exploitation rates in most lakes appear to maintain channel catfish abundance below the level at which negative effects may occur. [ABSTRACT FROM AUTHOR]

Ictalurid herpesvirus-2 (IcHV-2) is a pathogen of cultured black bullhead, Ameiurus melas (Rafinesque), and has been shown to produce high mortality in experimental exposures of channel catfish, Ictalurus punctatus (Rafinesque). During acute infections, the virus grows readily in cell cultures but produces a cytopathic effect (CPE) similar to that of Ictalurid herpesvirus-1 (IcHV-1) and the channel catfish reovirus. We have developed a quantitative PCR assay that can be used to detect IcHV-2 in fish tissues and cell culture supernatants. The assay does not amplify other fish herpesviruses tested or host DNA. It is quantitative over a range of eight logs, and the limit of detection is <10 copies per reaction. In replicate assays carried out on different days, the coefficient of variability was 10%. The best organs for the detection of acute IcHV-2 infections by our assay are the spleen and kidney. This assay should be useful for the diagnosis of IcHV-2 disease, the identification of syncytial CPEs in cell cultures, and for the detection of latent infections in carrier fish. [ABSTRACT FROM AUTHOR]

The basic nutrient requirements for channel catfish, Ictalurus punctatus, are well known, with anecdotal evidence suggesting that catfish fry grow faster and have better survival when fed an animal protein diet. However, the ability to grow channel catfish as small as 11 g on all plant diets and a lack of published data showing the superiority of fish or animal proteins compared to nutritionally equivalent plant proteins for catfish fry indicates that it may be possible to raise channel catfish fry on diets with only plant protein sources. Therefore, an experiment was conducted to compare the effects of 36 and 45% animal protein diets and 36 and 45% all plant protein diets on catfish fry growth and survival. Experimental diets were formulated to contain: 36% all plant protein (primarily from soybean meal); 36% animal and plant protein (≥45% of crude protein as fish meal); 45% all plant protein (primarily from soy protein concentrate and soybean meal); and 45% animal and plant protein (≥60% of crude protein as fish meal). The catfish were fed at a rate of 20% of body weight daily for 28 d using 24-h automated feeders. Mean ending weights and lengths of catfish fry were not significantly different ( P > 0.05) for any treatment. Mean mortality was also not significantly different ( P > 0.05) among diets. Regression analysis of growth rate and analysis of variance of final weights revealed that there was no significant difference in growth rate for any of the four diets. These results indicate that growth is not limited in channel catfish fry fed all plant protein diets, and that there is no apparent advantage to the inclusion of animal protein in diets for channel catfish fry. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The article examines whether feeding yeast-derived mannans in the form of Bio-Mos could improve growth, feed efficiency, and improve resistance of channel catfish challenged with Edwardsiella ictaluri (E. ictaluri). E. ictaluri is a bacterium that causes enteric septicemia of catfish. The results show that the addition of Bio-Mos to catfish diet does not improve weight gain, but may improve resistance to E. ictaluri.

Sagittal otoliths and the articulating process of the pectoral spine have both been validated as accurate techniques for estimating the age of channel catfish Ictalurus punctatus (≤age 4). However, there is limited information on the relative precision of estimates from these two structures. Thus, we analyzed the precision of age estimates derived from otoliths and the articulating process of the pectoral spine and compared the dynamic processes (recruitment, growth, and mortality) resulting from those estimates. Aging structures were removed from 110 channel catfish captured from the Wabash River (river kilometers 550-9.6) via day--time electrofishing. The age estimation methodologies were similar to those described in previous studies. Agreement between the ages derived from the two structures was high: the average percent error was 8.4%, the coefficient of variation was 11.4, and the slope of the age bias plots did not differ from 1, indicating similar age assignments between structures. The corresponding recruitment patterns, von Bertalanffy growth models, and mortality rates did not differ between the aging structures. We conclude that the articulating process of the pectoral spine provides age assignments similar to those of otolighs and that the dynamic processes do not differ between structures. Further, based on the results of this study, the articulating process of the pectoral spine provides a suitable alternative to otoliths and has the advantage that channel catfish do not have to be sacrificed. [ABSTRACT FROM AUTHOR]

Over-fertilization with phosphorus and carryover copper residual in the sediment from copper sulfate treatment in double-cropped ponds were suspected as the primary causes of low larval percid survival in coolwater aquaculture ponds. Consequently, in this study, we compared saugeye (male sauger Sander canadensis X female walleye S. vitreus) survival, growth, and yield among ponds that were single-cropped with only saugeyes in the spring during the previous two consecutive years (SS ponds) and ponds that were double-cropped (with saugeye culture in the spring and channel catfish Ictalurus punctatus culture in the summer) during the previous two consecutive years (DD ponds). We also compared sediment phosphorus (soluble reactive phosphorus [SRP] and total phosphorus [TP]), sediment copper concentrations, phytoplankton biomass, and zooplankton biomass. Fish survival (number harvested) and fish yield (mass harvested) were significantly lower in DD ponds than in SS ponds in 2001 but were similar in 2002 (a year of wide temperature fluctuation early in the production season). Sediment analyses revealed that DD ponds had significantly lower SRP and TP but higher copper concentrations than did SS ponds. A detailed study done in 2002 revealed that individual length and wet weight of percids were significantly higher in the SS ponds than in DD ponds; phytoplankton biomass was similar in both sets of ponds, while zooplankton biomass was significantly lower in DD ponds. These results suggest that residual materials used in double-cropped channel catfish ponds may negatively affect subsequent years' percid culture. [ABSTRACT FROM AUTHOR]

The nominal Yaqui catfish,Ictalurus pricei, is a species of Ictaluridae (Siluriformes) often recorded from Northwest Mexico. Southern distribution members of theI. priceicomplex in Northwest Mexico include at least one undescribed species that differs from Yaqui catfish in morphological features, herein called “Sinaloa Catfish”. Sequencing of four geographical mitogenome haplotypes of Yaqui catfish and Sinaloa catfish showed geographical haplotypes ofI. priceiwithin a clade of specific identity, close to Sinaloa catfish haplotypes. Our molecular phylogeny represents a working hypothesis supporting information on the evolutionary relationships of theIctalurusspecies from Western Mexico and Western USA. [ABSTRACT FROM AUTHOR]

The interspecific hybridization of channel catfish, Ictalurus punctatus, females with blue catfish, I. furcatus, males has been identified as a method to further improve production; however, lack of spawning success has affected its commercial application. To facilitate our understanding of the interaction of brood stock nutrition and reproductive performance, we evaluated the interaction of feed quality and feeding frequency. Channel catfish females were classified into two genetic groups, namely, high and low spawning. The treatments were offered during the spring season 70–90 d prior to the start of the spawning season. Induced reproduction was performed using luteinizing hormone releasing hormone analog. Condition of the fish as well as reproductive performance using spawning success, egg production, egg size, and fertilization at 48 h were determined. Changing protein level of the diet from 32 to 42% did not influence spawning, fecundity, or fertilization, but affected egg size and biochemical composition of the eggs. Increasing the feeding frequency from three to six times per week negatively affected spawning in one of the two genetics groups, did not affect egg production and egg fertilization, but had a significant effect on egg size. Older fish performed better than younger fish in terms of spawning success and egg production. [ABSTRACT FROM AUTHOR]

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Cooking to 63C for 15 s remains an important step to ensure safe fish for human consumption. Methods for heat process verification have not been validated for channel catfish (Ictalurus punctatus ). The present research compared extractable protein quantification, lactate dehydrogenase, acid phosphatase and catalase activity assays for verification of internal cooking temperature of channel catfish fillets. Ground raw catfish fillet samples (fresh and frozen) were cooked to 55, 60, 62, 63, 64 and 66C. Extractable protein, acid phosphatase and catalase activities decreased as internal cooking temperature increased, but lactate dehydrogenase activity remained unchanged. Samples cooked to 63C had extractable protein concentrations between 9.11 and 10.02 mg/g (95% confidence). Catalase was rapidly inactivated between 55 and 60C and may be suitable for identification of severely undercooked product. Acid phosphatase activity was influenced by method of storage (fresh versus frozen). A method based on total extractable protein appeared to be the most promising for determining the end point cooking temperature of catfish. PRACTICAL APPLICATIONS The most precise and reliable method to verify maximum cooking temperature attained during heat treatment of catfish fillets was total extractable protein. This finding may be useful for critical control point verification and may be valuable where claims of foodborne illness associated with catfish consumption are being litigated or investigated. To confirm gross undercooking, an easier test would be to measure catalase activity. [ABSTRACT FROM AUTHOR]

Fungal infestations of channel catfish Ictalurus punctatus eggs can lower hatch rate, which requires the producer to spawn more channel catfish or risk fingerling shortages. Hydrogen peroxide (H2O2) treatments (0.0, 15.6, 31.3, 62.5, 125,250, 500, 1,000, 2,000, and 4,000 mg/L) were evaluated to determine their effect on channel catfish hatch rate (number of fry/number of eggs X 100) and control of naturally occurring infestations of fungi Saprolegnia spp. in an experimental compartmentalized trough hatching system. Experiments were run at water temperatures of 23.2-24.0°C, dissolved oxygen concentrations of 4.5- 6.8 mg/L (53-79% saturation), total alkalinity of 209-217 mg/L, and total hardness of 91-110 mg/L. Treatments were applied to hatching compartments while well water was flowing at a rate of one water exchange every 30 rain and egg density was 2.5 g eggs/L of water. Observations for fungal development were made daily, and the maximum measure of fungal growth was recorded. An initial range-finding study demonstrated that H2O2 concentrations greater than 500 mg/L lowered the hatch rate. In later experiments, concentrations of 125, 250, and 500 mg/L applied for 6 d significantly increased the hatch rate and reduced fungal growth when compared with the controls. The 250-mg/L H2O2 treatment had the highest mean hatch rate (64.4% compared with 24.7% for the controls), lowest incidence of fungal infestation (27.3% compared with 100% for the control), and the lowest average fungal growth (an average measure of 0.95 cm compared with 7.23 cm for the controls). [ABSTRACT FROM AUTHOR]

A 4-year pond study was conducted to compare net production, feed conversion, processing yield, and body composition of channel catfish Ictalurus punctatus that were fed once daily, fed every other day (EOD) to satiation, or fed an amount not exceeding 110 kg.ha⋅ha-1⋅d-1 in a multiple-batch cropping system. The greatest amount of feed administered was observed for the daily satiation group, followed by the 110-kg⋅ha-1d-1 group and the EOD group (P ≤ 0.05). Net production of fish fed daily to satiation did not significantly differ from that of fish fed up to 110 kg⋅ha-1⋅-1, but that of fish fed daily (satiation or ≤ 110 kg/ha) was significantly higher than that of fish fed EOD to satiation. Feed conversion ratio was significantly lower in fish fed up to 110 kg⋅ha-1⋅d-1 or EOD to satiation than that of fish fed daily to satiation. Carcass, fillet, and total meat yields did not differ among feeding regimens. Fish fed EOD to satiation had lower fillet fat and higher fillet moisture than fish fed daily to satiation. Feed restriction to no more than 110 kg⋅ha-1⋅d-1 did not significantly affect fillet composition of channel catfish compared with fish fed daily to satiation. It appears that limiting the feeding rate to 110 kg⋅ha-1⋅-1 at a stocking density of 14,830 fish/ha would improve feed efficiency without causing significant reduction in weight gain, net production, or processing yield and would thus increase farm profits. Feeding channel catfish EOD to satiation may be acceptable as a short-term strategy when economic conditions justify it. However, it may not be economical for the long term because of lower production, increased length of the production cycle, and reduced processing yield. [ABSTRACT FROM AUTHOR]

A study was conducted to examine the effect of dietary levels of distiller’s dried grains with solubles (DDGS) on growth, body composition, hematology, immune response, and resistance of channel catfish, Ictalurus punctatus, to Edwardsiella ictaluri challenge. Five diets containing 0, 10, 20, 30, and 40% DDGS with supplemental lysine (Diets 1–5) as partial replacements of a combination of soybean meal and cornmeal on an equal protein basis were fed to juvenile catfish (13.33 ± 0.25 g) for 12 wk. Growth performance and feed utilization efficiency were similar for fish in all treatments. Body lipid and moisture increased and decreased, respectively, in fish feed DDGS-containing diets relative to the control group. Dietary treatment had no effect on red and white blood cell counts. Hemoglobin and hematocrit were significantly higher in fish fed diets containing DDGS than in those fed the control diet. Fish fed 20–40% DDGS diets had increased serum total immunoglobulin, and those fed the 30% DDGS diet had significantly increased antibody titers 21 d following E. ictaluri challenge. Other immune variables evaluated were not affected by dietary treatments. Preliminary results on bacterial challenge showed an increased resistance against E. ictaluri in fish fed DDGS-containing diets (Diets 2–5). [ABSTRACT FROM AUTHOR]

Black bullheads Ameiurus melas are an environmentally tolerant omnivorous fish species that are found throughout much of North America and parts of Europe. Despite their prevalence, black bullheads are an infrequently studied species making their biology, ecology, and life history poorly understood. Although limited information has been published on black bullheads, evidence suggests that bullheads can dominate the fish biomass and have profound influences on the fish community in some north temperate USA lakes. The goal of our study was to provide additional information on black bullhead population demographics, growth rates, life history characteristics, and seasonal diet preferences in a northern Wisconsin lake. Using common fish collection gears (fyke netting, electrofishing), fish aging protocols, fecundity assessments, and diet indices, our results suggested that black bullheads exhibited relatively fast growth rates, early ages at maturity, moderate fecundity, and a diverse omnivorous diet. Due to these demographic and life history characteristics, black bullheads have the potential to dominate fish community biomass in their native and introduced range. Results from our study may inform the management of black bullhead as native and invasive species. [ABSTRACT FROM AUTHOR]

Animal protein, generally fish meal, has traditionally been used in the diet of channel catfish. However, our previous research indicates that animal protein is not needed for growing stocker-size catfish to food fish when the fish are stocked at densities typical of those used in commercial catfish culture. Whether this holds when fish are stocked at high densities is not known; thus, we conducted an experiment to evaluate the effect of feeding diets with and without fish meal to channel catfish stocked in earthen ponds at different densities. Two 32% protein practical diets containing 0% or 6% menhaden fish meal were compared for pond-raised channel catfish, Ictalurus punctatus, stocked at densities of 14,820, 29,640, or 44,460 fish/ha. Fingerling channel catfish with average initial weight of 48 g/fish were stocked into 30, 0.04 ha ponds. Five ponds were randomly allotted for each fish meal level × stocking density combination. Fish were fed once daily to satiation for two growing seasons. There was a significant interaction between stocking density and fish meal for net production; net production increased in fish fed a diet containing fish meal compared with those fed an all-plant diet at the highest stocking density, but not at the two lower stocking densities. Net production of fish fed diets with and without fish meal increased as stocking density increased. Viewing the main effect means, weight gain decreased and FCR increased for fish stocked at the two highest densities, and survival was significantly lower at the highest stocking density. Visceral fat decreased in fish at the two highest stocking densities. Body composition data were largely unaffected by experimental treatment except for a reduction in percentage of filet fat in fish at the highest stocking density, and fish that were fed diets containing fish meal had a lower percentage of fillet protein and a higher percentage of fillet fat. It appears that at stocking densities two to three times higher than generally used, animal protein (fish meal) may be beneficial in the diet of channel catfish. In regard to stocking densities, high stocking results in higher overall production, but the average fish size decreased as stocking density increases. [ABSTRACT FROM AUTHOR]