Comparison of growth performance among channel-blue hybrid catfish, ccGH transgenic channel catfish, and channel catfish in a tank culture system

Fish is an essential source of high-quality protein for people worldwide. The present study was designed to compare the growth performance among the channel-blue hybrid catfish, channel catfish transgenic for the channel catfish growth hormone (ccGH) cDNA driven by the antifreeze protein promoter from an ocean pout Zoarces americanus (opAFP-ccGH), and non-transgenic channel catfish control. Mean body weight of channel-blue hybrid catfish was 15.80 and 24.06% larger than non-transgenic channel catfish control at 4 and 18 months of age, respectively. However, transgenic opAFP-ccGH channel catfish were 5.52 and 43.41% larger than channel-blue hybrid catfish and 22.19 and 77.91% larger than their controls at 4 and 18 months of age, respectively. Significant differences in mean body weight between the sexes within all genetic types were found. Males were larger than females (P < 0.001). However, mean body weight of non-transgenic males was not larger than transgenic opAFP-ccGH females or male and female hybrid catfish. Condition factor of transgenic opAFP-ccGH channel catfish was higher (P < 0.05) than that of full-sibling, non-transgenic channel catfish and hybrid catfish. The mean percentage body weight gain of GH transgenic channel catfish was 559%, the channel-blue hybrid catfish was 384.9% and their non-transgenic controls channel catfish was 352.6%.

Haemato-biochemical and ionic regulatory responses of the hybrid catfish, Heteroclarias, to sublethal concentrations of palm oil mill effluents

Background Pollution arising from the noxiousness of palm oil mill effluent (POME) has become a serious threat to aquatic biotas. However, a paucity of information exists on fish response to POME-mediated oxidative stress, lipid peroxidation, haemato-biochemical, enzymatic and ionic changes. This study, therefore, evaluates the effects of 28-day exposure of Heteroclarias, a hybrid catfish, to POME. Juvenile Heteroclarias (n = 350, average weight: 11.90 ± 0.70 g and average length: 9.04 ± 0.71 cm) were exposed to sublethal concentrations (0-control, 4.00, 8.00 and 12.00 mg/l) of POME to determine its effects on red blood cells (RBC), haemoglobin (HB), packed cell volume (PCV), white blood cells (WBC), mean cell haemoglobin (MCH), mean cell haemoglobin concentration (MCHC) and mean cell volume (MCV). The activities of alanine aminotransaminase (ALT), aspartate aminotransaminase (AST), lactate dehydrogenase (LDH), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and the levels of malondialdehyde (MDA), calcium (Ca+), potassium (K+), magnesium (Mg2+) and sodium (Na+) ions were also assayed in the gill and liver. Results Exposure to POME caused significant (p < 0.05) concentration-dependent decrease in RBC, HB, PCV, MCV, MCH and MCHC values, whereas a significant (p < 0.05) concentration-dependent increase in WBC was observed in POME-exposed fish compared to the control. ALT, AST, LDH, GPx, SOD and CAT activities in the gill and liver significantly (p < 0.05) increased in a concentration-dependent manner. MDA level significantly (p < 0.05) increased in the gill relative to control, while in the liver it was insignificantly different. Both tissues exhibited an increase in Ca+, K+, Mg2+ and Na+ levels at the highest toxicant concentration with a rise of 77.93, 38.46, 109.54 and 41.99% recorded for the electrolytes in the gill and 79.17, 26.92, 55.48 and 38.78% in the liver above the control value, respectively. The levels of all the electrolytes except K+ were higher in the gill than the liver and were in the order: Na+ > K+ > Mg+ > Ca2+ in both tissues. Conclusions These results may be used as a suitable tool for pollution assessment and policy formulation to mitigate the discharge of untreated POME into aquatic ecosystems and their impacts on resident organisms.

Proximate and minerals compositions of three species of fish, Champsocephalus gunnari, Oreochromis niloticus and hybrid catfish sold in Birnin Kebbi, Kebbi State, Nigeria

Background: Fish is known to be one of the cheapest sources of animal protein and have essential nutrients needed in human diets. The present study investigated the proximate and nutrient composition of three species of fish, Champsocephalus gunnari, Oreochromis niloticus, and hybrid catfish (Clarias gariepinus). Methods: The sample collection, proximate and mineral analysis were conducted using the standard protocols of sample collections and chemical analysis. Results: The results revealed that Champsocephalus gunnari, Oreochromis niloticus, and Clarias gariepinus contain moisture (66.00±0.50%, 52.00±1.00%, and 70.00±0.20%), crude protein (9.20±0.1323%, 3.75±0.02%and 5.80±0.05%), crude lipid (10.16±0.91%, 2.37±0.01% and 12.00±0.30%), ash (11.92 ±0.02%, 39.40±0.03% and 11.97±0.06%), and crude fiber (2.03±0.01%, 2.36±0.02% and 0.19±0.01%) respectively. The mineral contents were: iron (4.50±0.01mg/kg, 3.70±0.01 mg/kg and 4.70±0.02mg/kg), Zinc (2.35±0.01mg/kg, 2.15±0.0100mg/kg and (1.89±0.01mg/kg) for Champsocephalus gunnari, Oreochromis niloticus, and Clarias gariepinus respectively, while copper was only detected in C. gunnari (0.25±0.01mg/kg). The same amount of chromium (0.01±0.00 mg/kg) was detected in all the samples. Manganese was undetected in all the samples. Conclusion: In conclusion, the present study demonstrated the nutritional value of Champsocephalus gunnari, Oreochromis niloticus and Clarias gariepinus. This information would help in choosing any of the fish bases on their nutritional values rather than taste and other physical features.

Occurrence and Development of Off-Odor Compounds in Farmed Hybrid Catfish (Clarias macrocephalus × Clarias gariepinus) Muscle during Refrigerated Storage: Chemical and Volatilomic Analysis

The goal of this study was to examine the changes in chemical parameters, major volatile compounds, and sensory aspects in farm-raised hybrid catfish (i.e., dorsal, lateral line and ventral muscles) during a 15-day period of refrigerated storage. Trichloroacetic acid-soluble peptides, free fatty acid, total volatile base-nitrogen (TVB-N), and non-heme iron levels in all muscles increased as storage time proceeded. The levels of trans-1,10-dimethyl-trans-9-decalol (geosmin) and 2-methylisoborneol (2-MIB) were higher than their thresholds, which was connected to a stronger earthy odor. The concentrations of geosmin and 2-MIB in all muscles increased, although there was a consistent trend of earthy odor throughout storage; this phenomenon could be attributed to the masking effect of other off-odors. During storage, the largest lipid oxidation was found in ventral muscle, as measured by peroxide value and thiobarbituric acid reactive substances. During storage, the formation of the most volatile products increased in the lateral line and ventral muscle, whereas the dorsal muscle had the lowest concentration. As storage time proceeded, the strength of spoiled, fishy, rancid, and overall off-odor intensity of all tested muscles tended to rise. Those alterations were linked to higher levels of TVB-N and trimethylamine, as well as all other volatile lipid oxidation products (e.g., hexanal, propanal, 2,4 heptadienal, 1-octen-3-ol, octanal, nonanal, trans-2-heptenal, and 1-hexanol).

Effects of dietary tryptophan on muscle growth, protein synthesis, and antioxidant capacity in hybrid catfish Pelteobagrus vachelli♀ × Leiocassis longirostris♂

The present study evaluated effects of dietary supplementation with tryptophan (Trp) on muscle growth, protein synthesis, and antioxidant capacity in hybrid catfish Pelteobagrus vachelli♀ × Leiocassis longirostris♂. Fish were fed six different diets containing 2.6 (control), 3.1, 3.7, 4.2, 4.7, and 5.6 g Trp kg−1 diet for 56 days, respectively. Results showed that dietary Trp significantly (1) improved muscle protein content, fiber density, and frequency of fiber diameter; (2) up-regulated the mRNA levels of PCNA, myf5, MyoD1, MyoG, MRF4, IGF-I, IGF-II, IGF-IR, PIK3Ca, TOR, 4EBP1, and S6K1; (3) increased phosphorylation levels of AKT, TOR, and S6K1; (4) decreased contents of MDA and PC, and increased activities of CAT, GST, GR, ASA, and AHR; (5) up-regulated mRNA levels of CuZnSOD, CAT, GST, GPx, GCLC, and Nrf2, and decreased Keap1 mRNA level; (6) increased nuclear Nrf2 protein level and the intranuclear antioxidant response element binding ability, and reduced Keap1 protein level. These results indicated that dietary Trp improved muscle growth, protein synthesis as well as antioxidant capacity, which might be partly related to myogenic regulatory factors (MRFs), IGFs/PIK3Ca/AKT/TOR, and Keap1/Nrf2 signaling pathways. Finally, based on the quadratic regression analysis of muscle protein and MDA contents, the optimal Trp requirements of hybrid catfish (21.82-39.64 g) were estimated to be 3.94 and 3.93 g Trp kg−1 diet (9.57 and 9.54 g kg−1 of dietary protein), respectively.