Feeding Tilapia in Intensive Recirculating Systems

There are many species of tilapia, but only a few are widely cultured around the world. In the United States the most commonly cultured species of tilapia are the Nile (nilotica), Blue (aurea), Mozambique (mossambicus), Hornorum (hornorum), and hybrids such as the Taiwanese and Florida red. Choosing a species to culture depends largely on customer preference, legal status, growth rate and cold tolerance. Tilapia are well suited for culturing in ponds, cages, tanks, or raceways. Using ponds is the most popular method in the southern United States due to longer growing seasons. In the southern most parts of Texas and in Florida water temperatures can remain warm enough for year-round growth. In the cooler, temperate regions of the North and Midwest, tank culture is favored

Commercial production of Florida pompano (Trachinotus carolinus) larvae at low salinity induces variable changes in whole-larvae microbial diversity, gene expression, and gill histopathology

IntroductionSalinity presents economic and technical challenges in land-based recirculating aquaculture systems (RAS) in the U.S. warm water marine finfish aquaculture industry. Many studies have shown euryhaline fish reared at salinities closer to their iso-osmotic salinity can yield enhanced production performance as well as potential reduced costs to farms. However, there is potential for osmotic stress in fish larvae to negatively impact larvae microbiome and innate immune system. Florida pompano (Trachinotus carolinus) is a popular sportfish has been targeted for land-based RAS due to its impressive market value and euryhaline capacity. This study investigated the impacts of rearing Florida pompano larvae at salinities closer to their iso-osmotic salinity.Materials and methodsLarvae were cultured at 10, 20, and 30 ppt in triplicates, and larvae samples were collected for histopathology, microbiome, and whole transcriptomics analysis every three days from hatching until the time of weaning (24 days post hatch [DPH]). Water samples were also taken for microbiome analysis on every other larval sampling day. DiscussionThese changes were driven more by metamorphosis, causing an increase in expression of antioxidant genes (cat, gss, gsto1, and scara3) than by the presence of potentially pathogenic genera, which failed to induce an immune response (low or unchanged expression of downstream elements of the NOD1 or TLR5 pathways). These findings provide baseline information on Florida pompano low salinity tolerance in larviculture during early developmental stages. In addition, we have shown minimal effects on the immune system at salinities as low as 10 ppt. This work has important implications for larval health management and can be used to refine and direct future research regarding improving commercial production of warm water marine specie

Feeding Tilapia in Intensive Recirculating Systems

There are many species of tilapia, but only a few are widely cultured around the world. In the United States the most commonly cultured species of tilapia are the Nile (nilotica), Blue (aurea), Mozambique (mossambicus), Hornorum (hornorum), and hybrids such as the Taiwanese and Florida red. Choosing a species to culture depends largely on customer preference, legal status, growth rate and cold tolerance. Tilapia are well suited for culturing in ponds, cages, tanks, or raceways. Using ponds is the most popular method in the southern United States due to longer growing seasons. In the southern most parts of Texas and in Florida water temperatures can remain warm enough for year-round growth. In the cooler, temperate regions of the North and Midwest, tank culture is favored.This article is from NCRAC Fact Sheet Series #114. Used with permission.</p

Effect Of Feeding Frequency On Consumption, Growth, And Efficiency In Juvenile Tilapia (Oreochromis Niloticus)

Triplicate groups of juvenile Oreochromis niloticus (34.4 g) were fed a commercial diet once, twice, three, or five times a day for 29 days. Consumption, growth, and feed utilization were eval- uated. No significant differences in growth, feed efficiency, or protein utilization were detected among the fish fed two, three, or five times daily, but all were significantly better than in fish fed only once. Fish fed three meals had significantly higher gross energy and lipid and lower crude protein contents than fish in the other treatments (p<0.05). Energy retention in fish fed three times daily (84.7%) was significantly higher than in fish fed five times (49.4%). Feeding juvenile tilapia nutrient dense pelleted feeds obviates the need for frequent feedings

Efficacy of a Commercial Probiotic Relative to Oxytetracycline as Gram‐Negative Bacterial Control Agents in a Rotifer (Brachionus plicatilis) Batch Culture

Two trials were conducted to evaluate two gram‐negative bacterial control strategies in batch cultures of the rotifer Brachionus plicatilis. In the first trial, rotifers at an initial density of 47/mL were cultured for 5 d and dosed with a 10‐mg/L solution of either oxytetracycline or a commercial probiotic consisting principally of Bacillus and Lactobacillus. In the second trial, rotifers at an initial density of 140/mL were cultured for 4 d and dosed with 20‐mg/L solutions of oxytetracycline or the probiotic. Rotifer density, egg counts, and egg : female ratios were determined daily. At the termination of trial 1 and on days 0, 2, and 4 of trial 2, counts of bacterial colonies were conducted to estimate bacterial loads in the rotifer culture water. Oxytetracycline was an effective antimicrobial and enhanced rotifer production in the higher‐density culture but had only a marginal effect on production in the lower‐density culture. Conversely, inoculation of the low‐density culture with the probiotic had no effect on rotifer production. Inoculation of the high‐density culture adversely affected rotifer production by increasing mortality and reproductive inhibition

Production Characteristics and Body Composition of Juvenile Cobia Fed Three Different Commercial Diets in Recirculating Aquaculture Systems

The effect of feeding three commercial diets on production characteristics and body composition of juvenile cobia Rachycentron canadum reared using recirculating aquaculture systems (RASs) was assessed in a 56-d growth trial. Juvenile cobia (mean weight ± SE, 29.2 ± 0.7 g) were stocked into three 8-m3 tanks in each of four RASs at an initial density of 1.2 kg/m3. After stocking, fish were fed one of three commercial diets: Hybrid Striped Bass diet (HSB; 44% protein, 12% lipid), Finfish Gold diet (GOLD; 42% protein, 16% lipid), or Marine Grower diet (MG; 50% protein, 15% lipid), all at a targeted feed rate of 3–5% of body weight per day. At 2-week intervals, 10% of the population of each tank was collected to determine mean weight, weight gain, specific growth rate (SGR), feed conversion efficiency (FCE), and biomass. At the end of the rearing trial, the entire population of each tank was harvested to determine production characteristics and survival. In addition, fish were sampled to determine whole-body composition, hepatosomatic index, intraperitoneal fat ratio, energy retention (ER), protein efficiency ratio (PER), and protein productive value (PPV). Final weight (311.0 g), weight gain (281.8 g), SGR (4.23% per day), FCE (85.7%), biomass (11.20 kg/m3), and ER (32.7%) of fish fed the MG diet were significantly greater than those of fish fed the HSB and GOLD diets. No differences in survival, gross energy, ash, or crude lipid content existed among fish fed the three diets. Lowest dry matter content, lowest PPV, and highest protein content were observed in fish fed the HSB diet. Highest PER was observed in fish fed the GOLD diet. Although the cost of production per kilogram for rearing juvenile cobia with the MG diet would be greater, this cost could be offset by the 15% reduction in rearing time required as compared with the HSB and GOLD diets