Improve Fish Growth Research Articles

Performance of Oreochromis niloticus in recirculating aquaculture systems at different levels of daily protein intake

Recirculating aquaculture systems (RASs) are an efficient method for developing sustainable aquaculture and the development of a feed strategy for RASs could be a key factor for the success of culturing Oreochromis niloticus. The daily protein intake (DPI) mathematical function related to body weight (BW) was designed (DPI = −3.818 ln (BW) + 30.158) named DPI 1.0 = 100%. Three feeding rates were established, DPI 1.4, 1.2 and 1.0, and were implemented in an RAS production cycle (100 fish/m3) for 34 weeks. The final growth measurements were 908.0 ± 57.9 g (DPI 1.4), 887.0 ± 113.5 g (DPI 1.2) and 702.2 ± 38.1 g (DPI 1.0) (p < .05), with feed conversion rates (FCRs) of 2.3, 1.9 and 1.9, respectively; the survival was ≥ 98.3% (p > .05) for all treatments. DPI levels conditioned the growth of the fish and the proportion of lipid: protein in the bodies of O. niloticus but not in the fillets. The mathematical function DPI 1.2 = 120% (DPI = −4.582 ln (BW) + 36.19) used in the RAS at the 40% protein level improved fish growth, the protein efficiency ratio and FCRs. The DPI values were estimated for 49 different cases and feeding strategies showed lower values than most of the different DPI mathematical functions used and cited in this work. Therefore, DPI metric is a good tool that provides the specific requirements of protein for O. niloticus growth, which can enable farmers to ration feed and improve energy use (kWh/fish) and facilitate the integration of RAS with horticulture.

Effects of dietary supplementation of bovine lactoferrin on antioxidant status, immune response and disease resistance of yellowfin sea bream (Acanthopagrus latus) against Vibrio harveyi

This study investigated the effect of the dietary supplementation of bovine lactoferrin (LF) on growth performance, hematological and immunological parameters, antioxidant enzymes activity and disease resistance against Vibrio harveyi in yellowfin sea bream (Acanthopagrus latus) fingerling. The fish with initial body weight 10 ± 0.3 g were randomly distributed at 10 fish per each 250 L fiberglass tank, and fed with four experimental diets (a control basal diet and three supplemented diets with 400, 800 and 1200 mg LF kg−1 diet) for 8 weeks. The obtained results showed that fish fed with LF supplemented diets had significantly higher final body weight as compared to control diet (P < 0.05). There were no significant differences between LF-treatments and the control group in white blood cell counts, red blood cell counts, hemoglobin and hematocrit. Total protein and complement activity (ACH50) in the serum of yellowfin sea bream were enhanced with increasing the dietary LF supplementation level (P < 0.05). The mucus lysozyme activity in fish fed on 800 and 1200 mg LF kg−1 was significantly higher than those fed on 400 mg LF kg−1 and control fish (P < 0.05). None of the antioxidant enzymes (catalase, glutathione reductase, glutathione S-transferase) was affected by LF supplementation (P > 0.05). Fish fed with dietary LF had a significantly higher survival rate than those fed with the control diet after challenge with Vibrio harveyi (P < 0.05). These results revealed that diet supplementation in A. latus especially with 1200 mg LF kg−1 improve fish growth performance and immune parameters, as well as survival rate against Vibrio harveyi.

Pemanfaatan Jahe (Zingiber officinale Rosc) untuk Memacu Pertumbuhan Ikan Nila (Oreochromis niloticus)

A research had been conducted to study the effect ginger supplemented in feed on growth of nile tilapia. Juveniles as much as 250 individuals (mean weight 27.31 g) were obtained from Fish Culture and Development Board (BP3I) Tateli. The fish were placed in plastic bags and transported to Faculty of Fisheries and Marine Science. Fish were then introduced in 15 aquaria at a density of 15 individuals per aquarium. Each aquarium was equipped with an aerator and used water recirculation system. After adaption for one weeks, fish was fed pellet supplemented with ginger powder as treatments at five different doses including A=0, B=2,5, C=5, D=7,5, and E=10 g/kg, each with three replications. Fish was fed treatment diets for four weeks at 3%/bw/day, twice daily at 08.00 am and 17.00 pm. Growth data including absolute and relative growth were weighted at the end of feeding period. Research results showed that after four weeks of feeding, supplementation of ginger powder into fish pellet significantly improved fish growth . The growth of fish fed pellet supplemented with 7.5 g/kg of food was and significantly different as compared to that of control fish. It was concluded that supplementation of ginger powder into fish pellet potentially improved fish growth. Keywords: Ginger, absolute growth, relative growth, nile tilapia

Water quality and nitrogen budget in turbot Scophthalmus maximus culture system supplemented with lactic acid bacteria

To understand the nutrient utilization efficiency and distribution in indoor fish culture system under treatment of probiotics, this study examined water quality and nitrogen budget in turbot Scophthalmus maximus culture system supplemented with four strains of lactic acid bacteria (LAB) isolated from fishery products. The results showed that the concentration of ammonia nitrogen (NH₃-N) and nitrite nitrogen (NO₂-N) in LAB treatments were all significantly lower (p < 0.05) than in the control group. The nitrate nitrogen (NO₃-N) in LAB treatments showed no significant differences (p > 0.05) compared with control group. The fish feed and water exchange accounted for 79.07% and 17.02% of total N input respectively. For N output, the drainage and residual diets in LAB treatment accounted for 24.50%–25.80% and 1.33%–1.60% respectively, and they were significantly lower than in the control group (27.60% and 2.20% respectively). Fish growth and lost N in LAB treatments accounted for 27.10%–30.50% and 11.00%–18.50% respectively, and they were both significantly higher (p < 0.05) than in the control group (22.30% and 5.30% respectively). The results indicated that the indigenous LAB strains were capable of improving fish growth, and reducing NH₃-N and NO₂-N level (at concentration of 105 cfu/ml) by directly adding in S. maximus culture water. Moreover, specific strains of LAB may increase nitrogen loss by promoting denitrification process in culture system.

Resveratrol attenuates oxidative stress and inflammatory response in turbot fed with soybean meal based diet

Adding immunopotentiators to plant protein based diets has been a feasible way to improve fish growth performance and healthy status. In this study, an 8-week trial was carried out to explore the effects of resveratrol, a natural polyphenolic compound, on growth performance, anti-oxidative capacity and immune responses in turbot fed soybean meal based diet. As the results showed, replacement 45% fish meal with soybean meal (SBM) significantly depressed the fish growth, feed utilization and the heights of villi and microvilli in distal intestine. The mRNA levels of hepatic antioxidant enzymes, including superoxide dismutase (sod), glutathione peroxidase (gsh-px) and peroxiredoxin 6 (prx 6), were highly inhibited in SBM group. The inflammation related genes in intestine were also responsive to soybean meal. Supplying resveratrol showed no effects on fish growth performance but significantly restored the intestinal morphology and improved the mRNA levels of hepatic antioxidant enzymes as well as the activity of SOD. Meanwhile, resveratrol significantly improved the mRNA levels of anti-inflammatory cytokine transforming growth factor-β and inhibited the expression of pro-inflammatory cytokines tumor necrosis factor-α (tnf-ɑ), interleukin-1β (il-1β) and interleukin-8 (il-8). The results indicate that resveratrol could attenuate the oxidative stress and inflammatory response induced by soybean meal in turbot. This study shows resveratrol is an effective immunopotentiator to carnivorous fishes fed plant protein sources.

Evaluation of minor carps intercropping in carp polyculture vis‐à‐vis other grow‐out cropping patterns of carp farming

One year grow-out evaluation of four cropping patterns of carps, viz. control: single stock single harvest (SSSH); T-1:intercrop of minor carps and Indian major carps (IMC); T-2:single stock multiple harvests (SSMH); and T-3:multiple stock multiple harvests (MSMH) was conducted in eight earthen ponds (0.09 ha each). Ponds were stocked with three IMCs (catla, rohu and mrigal) at 1:1:1 ratio at 10,000 fingerlings/ha combined density. T-1 was additionally stocked with 10,000 fingerlings/ha of minor carps (Puntius gonionotus, Labeo fimbriatus and Puntius sarana), while T-2 with additional 10,000 fingerlings/ha of the IMC. Periodic removal of partial biomass ensured prevalence of better water quality in treatments (higher water pH, higher dissolved oxygen and reduced inorganic nutrients). It helped to improve fish growth as average harvested weight of rohu and mrigal remained similar in treatments despite the presence of greater inter- and intraspecific competitions in intercrop and SSMH, respectively, and periodic stocking of younger juveniles in MSMH. Catla showed significantly higher growth in MSMH. The biomass yield in intercrop, SSMH and MSMH were 21%, 17% and 24% higher than SSSH, but the respective net incomes were 32.9, 21.3 and 56.5% higher. Partial harvest also helped reducing FCR in the order T-3<T-2<T-1<control. While the study showed MSMH as the most productive cropping pattern for biomass yield, the intercrop of minor carps and IMCs proved to be the most water productive (gross and consumptive water use) cropping method to produce varied fish protein with higher biomass yield.

ENHANCING GROWTH PERFORMANCE AND FEED UTILIZATION USING PREBIOTICS IN COMMERCIAL DIETS OF NILE TILAPIA (Oreochromis niloticus) FINGERLINGS

An experiment was undertaken to study the impact of commercial β-glucan on growth performance, feed utilization and immunomodulatory effects of Nile tilapia fingerlings. Four isocaloric and isonitrogenous diets were formulatedwith three levels of β-glucan (0, 0.6, 1.2 and 1.8%) and fed to the fish for 84 days. The tested diets were applied in 12 fiberglass tanks (80 x 60 x 60 cm) each was supplied arbitrarily with 20 Nile tilapia fingerlings with anmoderate starting body weight of 10 ± 0.20g. Generally, We found that adding β-glucan to the diet improve fish growth performance, feed conversion ratio, protein efficiency ratio and Apparent protein digestibility were enhanced for tilapia fingerlings compared to fish fed on the control diet. In terms of blood estimations no critical contrasts were identified in plasma albumin, total protein and total globulins of fish nourished on the tested diets. Conclusively, the results revealed that It is possible to include concentrations of 0.6 % of β-glucans in the diets for Nile tilapia, with detectable improvement on growth performance, feed utilization and survival.

Nghiên cứu khả năng sử dụng sinh khối Artemia ương cá tai tượng (Osphronemus goramy) giai đoạn giống

The study was conducted to evaluate the use of frozen Artemia biomass to replace commercial feed in nursing the giant gourami (Osphronemus goramy). The proportion of Artemia biomass (based on dry weight) in a feeding ration was gradually increased 25% for each treatment. The initial length and weight of fingelings were 2.65±0.19 cm/ind and 0.58±0.14 g/ind, respectively. The results after 45-day culturing showed that the length of fish in all the Artemia-fed treatments was significantly better than that obtained in the control (100% commercial feed). The optimum growth of fish in term of individual weight significantly improved in the Artemia-fed treatments as compared to that obtained in the control. The Artemia biomass improved fish growth as well as survival. The results indicated that the frozen Artemia biomass can be used as a feed source for the giant gourami fingerling.

Effects of dietary cineole administration on growth performance, hematological and biochemical parameters of rainbow trout (Oncorhynchus mykiss)

The aim of this study was to investigate the effects of dietary 1,8-cineole (cineole) administration on rainbow trout growth performance and health. The fish were fed with cineole supplemented diets [0 (control), 0.05, 0.1, 0.25, 0.5 and 1%] for 50 days. Thereafter, the fish growth performance, survival rate and proximate composition, blood RBC, hemoglobin (Hb) and hematocrit (Hct), levels of serum total protein, albumin, globulin, triglyceride and cholesterol, and activities of serum aspartate aminotransferase (AST) and alkaline phosphatase (ALP) were investigated. The results showed that the fish growth performance increased along with increase in dietary cineole levels up to 1%. The cineole treated fish had 100% survival; whereas the control survival rate was 88.9%. The cineole-treated fish had significantly higher serum total protein and globulin compared to the control group. Cineole at 0.25–1% levels significantly increased blood RBC, Hb and Hct levels, and decreased serum triglyceride levels and AST and ALP activities compared to the control group. Serum cholesterol levels showed significant decrease at the cineole levels of 0.5 and 1% compared to the other treatments. In conclusion, the results suggest that dietary cineole is capable to stimulate trout immune function and mitigate hemolysis and serum lipid levels. Such health benefits may explain the improved fish growth performance and survival rate. According to the results, dietary cineole supplementation at 0.84–0.88% would be beneficial in rainbow trout.

Microalga Isochrysis galbana in feed for Trachinotus ovatus: effect on growth performance and fatty acid composition of fish fillet and liver

Seeking alternatives to the depleting fish oil are crucial for marine fish aquaculture, which is currently dependent on fish oil as the primary source of n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs). Five isonitrogenous (46% crude protein) and isolipidic (16% crude lipid) feed diets (FO, ISO2.9, ISO4.8, ISO6.7, ISO8.6) were formulated by partially replacing fish oil with microalgae Isochrysis galbana. These diets were fed to triplicate tanks of Trachinotus ovatus (mean initial weight 1.92 g) for 80 days. This work demonstrates that a moderate inclusion (around 4.5–5.0 wt%, equivalent to the replacement of 24–26 wt% fish oil) of I. galbana biomass in fish diet improves fish growth performance, lipid deposition and enhances total n-3 fatty acids, DHA, and EPA contents in neutral and polar lipids (PLs) of fish muscle and liver of T. ovatus. The results disclosed in this study suggest that I. galbana microalgae represents a potential high-quality substitute for fish-based ingredients in aquaculture feeds, which can be a promising sustainable solution to resolve the depleting fish oil resource in a cost-effective manner.

Effects of Formulated Diet Co-fed with Minced Fish on Growth, Digestion, Metabolism, and Appetite Regulation, of Mandarin Fish Hybrid (Siniperca chuatsi ♀× Siniperca scherzeri ♂)

This study examined the effects of a formulated diet combined with minced fish at ratios of 1:1 (Diet 1), 1:3 (Diet 2) and 0:1 (Diet 3) on growth, digestion, metabolism, and appetite of juvenile mandarin fish (initial weight, 10.63 ± 0.29 g). Fish were hand fed to satiation for 194 days. Weight and growth rate of the fish in the first 97 days were negatively correlated to decreased ratio of minced fish. The weight of fish fed Diet 2 (97 days) was significantly higher than that of fish fed Diet 1. There was no significant difference in the growth of fish fed Diets 2 or 3. The activities of pepsin in the stomach, alanine transminase (ALT), and aspartate transminase (AST) in the liver, significantly increased in relation to the enhanced formulated diet ratio. The mRNA level of leptin in the liver and ghrelin in the stomach increased as the minced fish ratio decreased. The mRNA level of neuropeptide Y (NPY) in the brain increased as formulated diet ratios increased. Combined feeding strategies increased the appetite of the mandarin fish hybrid, improved digestion and metabolism of formulated diets, and improved fish growth.

Effect of Different Supplementary Diets on Growing Rate, Fat and Protein Contents of Flesh Common Carp (Cyprinus carpio) Fingerlings

The effect of different supplementary diets containing humic substances and probiotics for common carp, based on growth rate, specific growth rate %, protein and fat content was investigated. Humic acid was mixed with different mineral elements and the gram-positive bacteria combined as probiotics supplementary diets. These supplements were added to the experimental basal diet (control) at a rate of 0.5%, 1% and 2%. Four groups of fingerling with an average mass of 0.5 g were fed on the experimental diets, three times per day for 11 weeks. 30 fish per tank were weighed randomly every week to measure their growth rate and at the end of the experiment, 5 fish from each treatment were weighed and their fat and protein content was analyzed individually. The results showed that 1% and 2% probiotics increased the growth rate while all treatments have less specific growth rate % than control. In relation to fat and protein contents, the results showed that fish fed with probiotics 1% had high fat and protein contents compared to other groups in general. All fish fed with different levels of supplemented diets showed a decrease in fat in compare with control group. However, protein contents in fish fed with HS 0.5% and probiotics 1% were significantly higher than control and other group of fish fed with different level of supplemented diets. These results suggest that humic acid substances cannot improve fish growth rate, but fat and protein contents could be changed slightly, while probiotic supplementary diets can improve growing rates, having a significant effect on protein content of fish meat.

Dietary amino acid profile affects muscle cellularity, growth, survival and ammonia excretion of meagre (Argyrosomus regius)larvae

Formulation of diets according to fish amino acid (AA) qualitative requirements may improve fish growth. Two diets with different AA profiles were tested on 16-day-old meagre during 20 days. The first diet had an AA profile closer to meagre larval AA requirements (BAL), whereas the second had a different AA profile (UNBAL). Results showed that larvae fed the diet with higher similarities to the AA profile of meagre carcass had a higher final weight (19.8 ± 0.5 mg versus 13.4 ± 1.8 mg) and lower ammonia excretion after being fed (0.6 ± 0.1 ml/(g DW. larvae. h) and 0.8 ± 0.1 ml/(g DW larvae. h)). A higher mean fibre area was obtained in 36 DAH larvae fed the BAL diet (224.8 ± 33.3 μm2 versus 158.8 ± 34.5 μm2) as well as higher larval weight. When fibre area distribution was analysed, a higher frequency of larger fibres was observed in 36 DAH BAL larvae, suggesting that fibre hypertrophy had a higher importance in this treatment. In conclusion, this study shows that meagre larvae fed a diet with an AA profile closer to their requirements had lower nitrogen losses and higher final weight, as result of higher muscle hypertrophy.

Ameliorative effect of propolis supplementation on alleviating bisphenol-A toxicity: Growth performance, biochemical variables, and oxidative stress biomarkers of Nile tilapia, Oreochromis niloticus (L.) fingerlings

Bisphenol-A (BPA) is one of the important pollutants in aquatic ecosystems and its detrimental effect on fish has a great concern. Propolis is a natural immune-stimulant that has various biological and pharmacological activities. Thus, its capability to alleviate the toxic effect of BPA on Nile tilapia, Oreochromis niloticus (L.) performance was assessed in a study based on a 2×2 factorial design with two levels of ethanolic extract of propolis (EEP) and two waterborne BPA concentrations in triplicates. Fish (33.9±0.55g) were exposed to 0.0 or 1.64μgBPA/L for 6weeks during which fish were fed on diets containing 0.0 or 9.0gEEP/kg diet. Fish performance, biochemical variables, and oxidative stress enzymes were significantly affected by propolis supplementation, BPA exposure, and their interaction. Propolis supplementation significantly improved fish growth and feed intake, which were significantly retarded by BPA exposure. Additionally, total protein, albumin, globulin, and acetylcholine esterase (AChE) decreased significantly. Meanwhile aspartate transferase (AST), alanine transferase (ALT), alkaline phosphatase (ALP), creatinine, and uric acid increased significantly with exposure to BPA. Levels of malondialdehyde (MDA) as well as superoxide dismutase (SOD) and catalase (CAT) activities increased significantly due to BPA exposure, whereas significant reductions in the activity of glutathione peroxidase (GPx) and glutathione S-transferase (GST) were also recorded compared to the control fish. It is noticed that EEP co-administration ameliorated these parameters. The present results evoked that propolis administration improves fish growth and alleviated BPA-induced toxicity.

&lt;b&gt;Nile tilapia culture under feeding restriction in bioflocs and bioflocs plus periphyton tanks

Intensive aquaculture systems may cause pollution in water bodies because their effluents have high levels of nutrients. The use of substrates for periphyton and the manipulation of the C: N ratio of water are technologies that can be employed to increase aquaculture yield with environmental sustainability. The present study has aimed at determining whether feeding restriction could stimulate a greater use of natural food in three different Nile tilapia rearing systems (green water, bioflocs and biophyton), without growth performance impairment. There were nine treatments with four replicates each one (36 experimental units). The animals were raised in conventional (green water) tanks, C: N-ratio adjusted tanks (bioflocs) and bioflocs + periphyton integrated tanks (biophyton). In each culture system, the artificial diet was delivered regularly or under two levels of restriction (15 and 30%). In conventional tanks, fish growth performance was reduced by feeding restriction. Ammonia and nitrite were reduced in bioflocs tanks. Underwater structures for periphyton were not able to increase ammonia and nitrite removal. In bioflocs tanks, feeding restriction of 15% did not lessen fish weigh gain. Underwater structures for periphyton have not improved fish growth performance in any aspect.

Effects of feeding frequency on the enzymes and genes involved in oxidative stress in juvenile yellow catfishPelteobagrus fulvidraco(Richardson) exposed to ammonia

Optimal feeding strategies improve fish growth and health but may be affected by ammonia stress in closed rearing systems such as tanks or ponds. This study aimed to evaluate the effects of feeding frequency and ammonia levels in rearing water on the enzymes and genes involved in oxidative stress of yellow catfish. Experiment (ammonia exposure) and control groups were randomly assigned to one of three feeding frequencies (1, 2 and 4 times daily) for 8 weeks. Weight gain increased as feeding frequency increased from 1 to 4 times daily, but feed conversion ratio values decreased. The highest survival in ammonia group was found when fish was fed 2 times daily. Glutathione peroxidase activity and total antioxidant capacity in liver and brain of fish exposed to ammonia increased as feeding frequency increased from 1 to 4 times daily. Liver malondialdehyde content in control group decreased as feeding frequency increased from 1 to 4 times daily. The lowest liver malondialdehyde content in ammonia group was observed when fish was fed 2 times daily. Liver mRNA expression of superoxide dismutase and catalase in control group increased as feeding frequency increased from 1 to 4 times daily, but the highest superoxide dismutase and catalase expression in ammonia group were observed when fish were fed 2 times daily. This study indicates that higher feeding frequency of yellow catfish exposed to ammonia could result in oxidative stress and poor survival. The optimal feeding frequency of yellow catfish exposed to ammonia is 2 times daily.

Plant essential oils as fish diet additives: benefits on fish health and stability in feed

AbstractNutritional strategies focused on the use of phytochemicals as modulators of immunological and physiological responses, as well as antistress and antioxidant therapies and health promoters of the gastrointestinal tract have attracted increased interest in animal production. Over the past two decades, several studies have reported positive results of using plant essential oils (EOs) as dietary additive in several farm animal species. Recently, these nutritional alternatives have been evaluated and reported in fish production in order to enhance the resistance to diseases and prevent outbreaks, as well as to improve fish growth, animal welfare and feed utilization. However, despite the diverse and relevant biological activities reported, these phytochemicals are composed of often unstable and volatile molecules, which makes the chemical and physical characteristics of the EOs important aspects to be considered in fish nutrition research. This review summarizes the current knowledge regarding the use of plant EOs as fish dietary additives, focusing on their potential as modulators of the gut bacterial community and discussing some aspects regarding their stability in feeds.

The effects of dietary Betaplus®and TechnoMos®on growth performance, blood parameters, and intestinal microflora in juvenile kutum,Rutilus kutum(Kamensky, 1901)

The main goal of the current study was to assess the combined effects of a dietary probiotic Betaplus and prebiotic TechnoMos on growth performance, blood biochemical parameters, and intestinal microflora in juvenile Rutilus kutum. Four experimental diets were prepared with the addition of Betaplus and/or TechnoMos to a basal diet for R. kutum juveniles. The diets were randomly assigned to one of 12 tanks, with three replications per diet. The results showed that supplementation of both pro- and prebiotic, separately or in combination, improved fish growth parameters (p < .05). These additives also reduced fish mortality rates, either alone or in combination (p < .05). Protein content of the carcass increased by an addition of Betaplus (p < .05), but Betaplus supplementation reduced the fat content of the carcass (p < .05). Bacillus leicheniformis and B. subtilis counts were elevated by the addition of Betaplus and TechnoMos, with even a larger bacterial count observed in fish fed a mixed diet of pro- and prebiotics (p < .05). White blood cell counts increased with both pro- and prebiotic supplementations. Glucose and cortisol levels significantly decreased with the administration of Betaplus and TechnoMos, and the mixed treatment showed the lowest estimate of these parameters (p < .05). In conclusion, a better performance of juvenile R. kutum fed a diet mixture of Betaplus and TechnoMos is probably related to the elevation of Lactobacillus counts in the fish gut, which improves the digestive performance.

Dietary EDTA supplementation improved growth performance, biochemical variables, antioxidant response, and resistance of Nile tilapia, Oreochromis niloticus (L.) to environmental heavy metals exposure

Feed supplements are generally used to improve fish growth, health, and immunity but their potential use to enhance fish resistance against environmental stress is limited. An eight-week feeding trial was conducted to determine the effect of sodium salt of ethylene diamine tetraacetic acid (EDTA) supplementation on growth performance, biochemical and antioxidants response, body composition, and resistance of Nile tilapia, Oreochromis niloticus (L.) to environmental heavy metals (HM) exposure. Fish (16.2±0.28g) were fed on diets enriched with 0.0, 5, 10, 15, and 20g EDTA/kg diet. After that, fish were exposed to synthetic mixture of lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn) concentrations similar to those in the natural polluted habitat for 7days. Fish performance and feed intake improved significantly with increasing EDTA levels up to 10g/kg diet after which fish growth declined. All biochemical variables are significantly affected by EDTA supplementation, HM exposure, and their interaction. In response to EDTA supplementation, antioxidant activities were improved due to EDTA supplementation especially when fish fed 10–20g EDTA/kg diet. Post HM exposure, the control fish exhibited highest superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities and lowest malondialdehyde (MDA) value; meanwhile, antioxidant activity of fish fed 10–20g EDTA/kg diet was significantly improved and it was near that of fish prior HM exposure. Regarding whole-fish body constituents, only crude protein content was significantly higher in EDTA-fed fish than the control fish. After HM exposure, total ash contents and HM residues were significantly higher but crude protein and total lipids contents were significantly lower than those of the control fish. It is also noticed that EDTA supplementation reduced HM concentrations in whole-fish body and subsequently reduced their impacts on biochemical and antioxidant activities especially in fish fed 10–20g EDTA/kg diet. The polynomial regression data of this experiment recommended the use of EDTA supplement at level of 13g/kg diet to improve fish performance and antioxidant activity.

Comparative effects of Shirazi thyme and vitamin E on some growth and plasma biochemical changes in common carp (Cyprinus carpio) during cadmium exposure

Phytobiotics include a large number of active components which potentially have a growth-promoting effects and antioxidant properties. This study was conducted to investigate the protective effects of Shirazi thyme and vitamin E on growth and plasma biochemical parameters of common carp exposed to cadmium. Fish (34 ± 3 g) were divided into four groups and fed four distinct diets including commercial diet without any additive (for control and metal only group) and supplemented with either 1% ground Shirazi thyme or 100 mg kg−1 vitamin E for 45 days. At the end of the feeding trial, all treatments except control group were exposed to sub-lethal concentration of waterborne cadmium for 15 days and sampling was done on days 0, 7 and 15 after the metal exposure. According to the results, dietary inclusion of thyme prevented the harmful effects of cadmium and also improved fish growth and nutritional indices including weight gain, feed conversion ratio, specific growth rate and condition factor. Results also revealed that Shirazi thyme was more effective than vitamin E. Similarly, no changes in the hepatosomatic, viscerosomatic and bile somatic indices were observed. Plasma enzymes (AST, ALT, ALP and LDH) and metabolites were not altered due to thyme supplementation compared to the control. In conclusion, dietary supplementation of 1% ground Shiraz thyme improved the growth and health status of fish and showed better hepatorenoprotective properties than vitamin E during waterborne cadmium exposure in common carp juveniles. It might be conceivable to consider Shirazi thyme as a potential phytobiotic for incorporation in fish diet.