The pharmacokinetics, bioavailability, and disposition of oxolinic acid (OA), a quinolone antibacterial drug, were examined in a warmwater (channel catfish (Ictalurus punctatus)) and coldwater fish species (rainbow trout (Oncorhynchus mykiss)). Studies were performed at 24 and 14 °C for catfish and at 14 °C for trout to compare temperature- and species-related differences. Analysis of OA pharmacokinetics when determined by HPLC provided elimination half-life [Formula: see text], volume of distribution (Vss), and clearance (Clb) estimates for 24 °C catfish, 14 °C catfish, and 14 °C trout of 40.9, 69.3, and 81.3 h, 939, 880, and 1817 mL/kg, and 16.3, 8.9, and 16.9 mL∙kg∙h−1, respectively. Following oral administration, OA plasma concentrations peaked between 8 and 24 h for all treatments; however, 14 °C trout and 14 °C catfish sustained peak concentrations for a longer duration than 24 °C catfish. Oral OA bioavailabilities were 56.0, 91.8, and 90.7% for 24 °C catfish, 14 °C catfish, and 14 °C trout, respectively. OA distribution data for muscle of 14 °C catfish demonstrated an inordinately high peak concentration and delayed time to peak relative to other treatments. Elimination half-lives of OA in muscle were 33.1, 54.3, and 141 h for 24 °C catfish, 14 °C catfish, and 14 °C trout, respectively.

Channel catfish virus disease (CCVD) has been described as a disease of fry and fingerling channel catfish (Plumb 1977). The virus has been isolated only from specimens while an active epizootic was in progress. Adult fish have been suspected of being carriers of the virus and circumstantial evidence suggests that vertical transmission from adult to offspring may occur. A method whereby adult carriers of CCV could be identified would provide a valuable management tool to the fish health manager.During the winter of 1983-84, six channel catfish, Ictalurtis punetattis (Rafinesque), used as broodfish were found dead in a broodfish pond at the Catfish Research Facility, Mississippi Agricultural and Forestry Experiment Station, Mississippi State, Mississippi. One moribund male broodfish was presented to the authors' laboratory for examination. Channel catfish virus (CCV) was isolated from that fish and from nine of the remaining 21 broodfish in the pond. This report will document what is believed to be the first successful isolation of CCV from channel catfish broodstock.The male brood channel catfish, designated case H6273, was presented alive to the laboratory for examination on 27 January 1984. Pond water temperature was 8^C. The fish was found swimming slowly at the edge of the pond. Upon examination, the fish appeared cachetic (total length=59-4 cm, weight=2-62 kg) and exhibited bilateral exophthalmia. Internally, 4-5 ml of a clear red fluid was found in the abdominal cavity and the liver appeared smaller than normal and brown in colour. Other internal organs appeared grossly normal.Microscopic examination of fresh preparations from the gills revealed a moderate infestation of Triclwdina sp. and Amhiphrya sp. Bacterial isolation was attempted from the posterior kidneys on to blood agar plates. Culture plates were incubated at 25"C for 10 days at which time they were negative for any bacterial growth. A portion of the posterior kidney was ground with a mortar and pestle, suspended in Hank's Balanced Salts Solution (M. A. Bioproducts), filtered (0-45 fxm), and the filtrate was inoculated on to a

Density reduction, supplemental feeding, and a combination of two treatments were evaluated as means to alleviate stunting of red swamp crayfish Procambarus clarkii in earthen ponds. Mean total yield of crayfish in low density control ponds averaged 1,218 kg/ha and was 1.5 to 2 times higher (P≤ 0.05) than either the high density control or treatment ponds. Mean individual harvest weight of crayfish averaged 15.1 g and did not differ among treatments. Mean total yield of crayfish in ponds receiving supplemental feed was 32% higher than non‐fed ponds (P≤ 0.05). Mean total yield and size of crayfish at harvest from reduced and non‐reduced treatments did not differ. Density reduction and supplemental feeding implemented in early April did not increase individual crayfish weight to the commercially desirable size of 20 g.

Sulfadimethoxine (SDM), a sulfonamide antibacterial drug, was examined in regards to bioavailability, pharmacokinetics, distribution, plasma protein binding, mass balance, and metabolism in the rainbow trout (Oncorhynchus mykiss). Analysis of SDM pharmacokinetics when determined by 35S counting (parent/metabolite combination) and HPLC (parent) provided estimates for t1/2α, t1/2β, Vss, and Clb, of 0.63/0.38 (h), 17.0/15.9 (h), 500.8/421.6 (mL/kg), and 22.7/21.8 mL∙kg−1∙h−1, respectively. Multiple dose administration of [35S]SDM resulted in a terminal t1/2 of 35.2 h. Sodium SDM (42 and 126 mg/kg) and free drug (42 mg/kg) oral bioavailabilities were 63, 50, and 34%, respectively. Plasma protein binding (15.8 ± 5.1%) was nonsaturable and nonspecific. Tissues attained the highest levels of SDM equivalents in the bile followed by the intestine, liver, blood, skin, kidney, spleen, gill, muscle, and fat, respectively. Mass balance studies demonstrated a minor role for branchial ((0.6 ± 0.24%) 25 h) and urinary ((5.46 ± 2.24%) 24 h) routes of elimination over the first 24 h. SDM and N4-acetylated SDM (N4-A-SDM) were the major constituents for branchial and urinary routes, respectively. Metabolite analysis for select tissues demonstrated a predominance of N4-A-SDM in bile, SDM in plasma, and N4-A-SDM in the liver 20 h after dosing.

Abstract.– Experiments were conducted to evaluate the effects of feeding time and frequency on the growth, survival, feed conversion, and body composition of channel catfish Ictalurus punctatus cultured in closed recirculating raceway systems. In separate experiments, two stocking sizes (18 and 232 g/fish) of channel catfish were examined. Treatments consisted of 1) feeding catfish once daily, 3% of body weight at 0800 h; 2) feeding catfish once daily, 3% of body weight at 1200 h; 3) feeding catfish once daily, 3% of body weight at 1700 h; and 4) feeding catfish three times daily, 1% of body weight at 0800 h, 1200 h, and 1700 h. Weight gain, specific growth, feed conversion, percentage survival, and fillet proximate composition of channel catfish among treatments did not differ (P > 0.05). The percentage visceral fat of channel catfish fed the single meal at 0800 h was significantly lower (P < 0.05) than channel catfish receiving multiple feedings, but was not different than the visceral fat content of channel catfish fed at 1200 h and 1700 h. Under the conditions of this study, results indicate neither feeding time or feeding frequency significantly influences the growth, survival, and body composition of channel catfish raised in closed recirculating raceway systems.