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1.
Intracerebroventricular (ICV) treatment with oleate or octanoate induced in Brockmann bodies (BB) and liver of rainbow trout changes in several parameters related to fatty acid (FA) sensing through FA metabolism, FA transport through FA translocase (FAT/CD36) and mitochondrial activity. Changes observed in BB were completely different to those observed in previous studies after treatment with the same FA either intraperitoneal (IP) or in vitro. Therefore, FA sensing in BB is apparently direct and not related to previous FA sensing in hypothalamus, but it could be influenced by changes in the levels of peripheral hormones like insulin. In contrast, results obtained after ICV treatment with FA in liver were comparable to those observed after IP treatment but different to those observed after in vitro treatment. Therefore, FA sensing in liver is apparently indirect and be the consequence of previous hypothalamic FA sensing followed by vagal and/or sympathetic outflow.  相似文献   

2.
Zhang  Yanpeng  Zhang  Zhen  Liang  Xu-Fang  He  Shan  Xu  Jing 《Aquaculture International》2021,29(6):2619-2634

Neuropeptide Y receptor Y8 (NPY8R) is a fish-specific receptor, whose role in feeding regulation remains poorly understood. In the present study, two subtypes of NPY8R (NPY8Ra and NPY8Rb) were identified in Chinese perch, and their amino acid sequences were highly conserved in fish. The predicted tertiary protein structures of human NPY1R, Chinese perch NPY8Ra, and NPY8Rb tended to be conserved as a whole. However, the predicted tertiary protein structures of sc-NPY8Ra and sc-NPY8Rb were different at several sites. Chinese perch NPY8Ra and NPY8Rb were mainly expressed in brain. Intracerebroventricular administration of siRNA-NPY8Rb significantly decreased the mRNA expression levels of NPY8Rb and POMC (appetite-suppressive gene) and significantly increased the food intake of Chinese perch at 2 h and 8 h after injection. Similar result has not been observed in the siRNA-NPY8Ra administration group. The above results suggested that NPY8Ra might not play a role in appetite regulation and NPY8Rb might be an effector in the negative feedback regulation of feeding in Chinese perch.

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3.
Aminergic neurotransmitters play important roles in the regulation of food intake. However, their effects on feeding in fish have been less explored and still unclear. In the present study, the effects of serotonin (5-HT) and dopamine (DA) on food intake were evaluated through intraventricular (ICV) administration in Chinese perch (Siniperca chuatsi) and the mRNA expression levels of neuropeptide Y (NPY), agouti gene-related protein (AgRP), and pro-opiomelanocortin (POMC) were detected. At 1 h post-injection, 5-HT significantly decreased food intake in a dose-dependent manner. The mRNA expression of NPY and AgRP were significantly decreased (p < 0.05), whereas the mRNA expression of POMC was significantly increased (p < 0.05), suggesting the involvement of NPY, AgRP, and POMC in inhibitory action of 5-HT on food intake in Chinese perch. DA significantly decreased (p < 0.05) food intake and AgRP mRNA expression at 1 h post-injection, indicating the inhibitory effect of DA on food intake might be mediated through AgRP. This might shed new light on the regulation of food intake in Chinese perch.  相似文献   

4.
Pike perch (Sander lucioperca) has been identified as specie destined to diverse European inland aquaculture, but knowledge on the nutritional requirements is weak. Therefore, we investigated the effect of varying dietary fatty acid (FA) profile by partial replacement of fish oil (FO) with vegetable oils on growth, FA and body composition of juvenile pike perch. An extruded basal diet containing 59 g kg?1 crude lipids (FO) was added with 60 g kg?1 FO, 60 g kg?1 linseed oil (LO) or 60 g kg?1 soybean oil (SO). The resulting dietary FA composition differed mainly in the triglyceride fraction and was characterized by highest amounts of linolenic acid (18:3 n‐3) in the LO diet and linoleic acid in the SO diet. Diet enriched with FO contained highest contents of highly unsaturated FA 20:5 n‐3 (eicosapentaenic acid) and 22:6 n‐3 (docosahexaenic acid). Pike perch were held in a recirculation system and each feeding group (in triplicate) was fed with experimental diets at a daily rate of 35 g kg?1 of biomass for 57 days by automatic feeders. Weight gain and specific growth rate of experimental feeding groups ranged between 18.47 and 19.58 g and 1.37–1.45% day?1 and was not affected by the dietary composition indicating that FO can be replaced by vegetable oils without negative impact on growth performance. In contrast to the whole body and muscle composition, liver tissue was affected by the varying diets. Liver tissues of fish fed diets enriched with vegetable oils showed significantly increased lipid contents of 162 (LO) and 147 (SO) g kg?1 and indicate decreased lipid utilization compared with fish fed FO diet (liver lipid content 112 g kg?1). Nevertheless, hepatosomatic index of pike perch was not influenced by dietary lipid composition. The FA profile of pike perch was generally determined by the dietary FAs.  相似文献   

5.
In this study we tested the hypotheses that higher fat diets will promote greater fat oxidation, and that medium‐chain fatty acids (MCFA) will be more readily oxidized than long‐chain fatty acids (LCFA). The oxidation of dietary MCFA (coconut oil labelled with 14C‐octanoic acid) and LCFA (olive oil labelled singly with 14C‐palmitic acid and 14C‐oleic acid) was measured in a metabolic chamber. MCFA and LCFA were included in the respective diets at 150 and 300 g kg?1. Polka dot grouper fed diets containing MCFA had a significantly higher (P < 0.05) respiration rate [2.4 mmol CO2 BW (kg)?0.79 h?1] and proportion of radioactivity in the respired CO2 (49.5%) than those fed diets containing LCFA [1.2 mmol CO2 BW (kg)?0.79 h?1 and 12.8%, respectively]. The amount of dietary fat did not significantly affect either of these two response attributes. The radioactivity in faeces and regurgitated material was low with diets containing MCFA, but was significantly higher with diets containing LCFA, and increased with increasing LCFA content, suggesting a decrease in digestibility. These results show that MCFA provide this species with a more readily utilizable source of energy than LCFA. Moreover, raising the amount of lipid in the diet above 150 g kg?1 did not increase the oxidation of fatty acids for energy.  相似文献   

6.
Preproghrelin, a gut/brain peptide, plays an important role in the regulation of food intake and energy homeostasis in teleost and mammals. In the present study, we obtained the full-length preproghrelin cDNA in Chinese perch. The preproghrelin messenger RNA (mRNA) tissue expression showed that level was much higher in stomach and pituitary than in other tissues. The fasting study showed, after gastric emptying (3–6 h), short-term fasting (6–12 h) increased preproghrelin expression in the stomach. While in the pituitary, fasting reduced preproghrelin expression at 1, 3, 12, and 48 h, presenting state fluctuation of self-adjustment. The temperature study showed that the mRNA expression of preproghrelin was the highest in the brain at 26 °C and highest in the stomach at 32 °C, respectively, with different optimum temperature in these two tissues, reflecting spatiotemporal differences of regulation by central nervous system and peripheral organs. The photoperiod study showed that normal light (11 h of lightness and 13 h of darkness) led to highest preproghrelin expression, both in the brain and in the stomach, than continuous light or continuous dark, proving food intake is adapted to natural photoperiod or normal light in this study. These results all indicated that tissue-specific preproghrelin expression of Chinese perch could be significantly affected by environmental factors. Short-term fasting of 6 h after gastric emptying, 26 °C, and normal light led to higher preproghrelin expression, which indicated potential appetite increase in Chinese perch.  相似文献   

7.
Chinese perch, an obligate piscivorous fish, could serve as an excellent model system for studies on the diversification of lipoprotein lipase (Lpl) and hepatic lipase (Hl) genes. In this study, we characterized the genomic structure, tissue expression and single nucleotide polymorphisms of Lpl and Hl genes in Chinese perch (Siniperca chuatsi). Consistent with findings in other vertebrates, Chinese perch Lpl gene consisted of ten exons and nine introns, and Hl gene consisted of nine exons and eight introns. The promoter region of Hl gene was not highly homologous to that of Lpl gene in Chinese perch. The mRNA expression of Lpl in Chinese perch was the highest in adipose tissue, followed by liver, brain, intestine and muscle, and the lowest in spleen, whereas Hl was almost exclusively expressed in liver. These results suggested that Chinese perch Lpl and Hl might be derived from an early duplication of an ancestral gene. Polymorphisms of Lpl and Hl genes were examined in feeders and non‐feeders of dead prey fish by direct sequencing of these genes in 130 fish from each group. Three SNPs (A1220T, G1221T and C1224G) were identified in Lpl gene, whereas none was identified in Hl gene. Diplotype 2 in Lpl gene was significantly correlated with acceptance of dead prey fish.  相似文献   

8.
This study investigated the lipid metabolism responses of common carp (Cyprinus carpio L.) to mulberry leaf meal (MLM) replacing of some fish meal in diet. Six iso‐nitrogenous and iso‐energetic diets containing different levels of MLM (0%, 6.3%, 12.6%, 18.9%, 25.2% and 31.5%) were prepared and fed to common carps in tanks for 56 days. Analysis showed that serum total protein, albumin contents and glutamic‐pyruvic transaminase, glutamic oxalacetic transaminase activities were not significantly different among treatments, blood glucose, cholesterol, high‐density lipoprotein and low‐density lipoprotein but triglyceride concentration depicted a declining trend in MLM supplementation groups compared with control. Liver and muscle lipid content decreased with increased supplementation of MLM in the diet. Hepatic lpl showed an up‐regulated trend in the MLM groups, apo‐a1 was up‐regulated in common carp fed 31.5% MLM diet, pparα was up‐regulated in 18.9% and 25.2% MLM groups, while apo‐a4, pparβ and pparγ were down‐regulated in all the MLM‐treated groups compared with control, fabp1 was down‐regulated in fish fed high‐MLM diets (≥25.2%). The results revealed that half of fish meal in common carp diet could be replaced by MLM with no hepatotoxicity; MLM promoted the reversal of cholesterol transport thereby reducing the cholesterol in blood; MLM elevated the ability of fatty acid oxidation of the common carp, but did not activated the activity of lipoprotein lipase fully, and the suppressed transportation of fatty acid affected the degradation of triglyceride in blood together; MLM reduced liver lipid contents might through suppressing the isolation and proliferation of adipocytes.  相似文献   

9.
To investigate the effect of dietary lipid levels on lipid metabolism in muscle and adipose tissue of large yellow croaker (Larimichthys crocea), fish (average body weight 150.0 g) were fed to one of three diets with a low (6%), moderate (12%, the control diet) or high (18%) crude lipid level for 10 weeks. The expression of genes related to lipoprotein clearance (lpl, ldlr, lrp1 and srbi), fatty acid transport (cd36, fatp1, fabp3 and fabp11), lipogenesis (fas and dgat2) and lipolysis (atgl, cpt1 and aco) in muscle and adipose tissue was analysed. In muscle of fish fed the low‐lipid diet, the expression of lpl, lrp1, fas, dgat2 and atgl was significantly downregulated, whereas fabp3 and fabp11 were significantly upregulated compared with those fed the control diet. In muscle of fish fed the high‐lipid diet, the expression of lpl, ldlr, lrp1, cd36, fabp3, fas and dgat2 was significantly decreased, while fabp11 expression was significantly increased compared with those fed the control diet. Compared with the control group, only a significant downregulation of fabp3 expression in adipose tissue was observed in the low‐lipid group. In the high‐lipid group compared with the control group, the expression of ldlr, fabp11, dgat2, atgl and aco in adipose tissue was significantly upregulated, whereas cpt1 expression in adipose tissue was significantly downregulated. These results indicated that the expression of the selected key genes related to lipid metabolism was tissue‐specific regulation by dietary lipid levels in large yellow croaker.  相似文献   

10.
The concentrations of monoamines in the hypothalamus were determined in yellow perch Perca flavescens before and after injection with lipopolysaccharide (LPS; 3 mg kg−1 fish weight) or saline to test for the presence of neurochemical changes potentially associated with changes in plasma cortisol characteristic of intraperitoneal (ip) challenge with LPS. In the first experiment, yellow perch were injected with saline or LPS and the hypothalamus removed and plasma sampled before and at 0.5, 1.5, 3.0, and 6 h after injection. Plasma cortisol was elevated in both saline- and LPS-injected fish through 1.5 h after injection and returned to levels resembling pre-injection by 3 h after injection. Significantly higher amounts of cortisol in plasma from LPS-injected relative to saline-injected fish were observed 6 h following injection. A significant decrease relative to levels observed 0.5–3 h after handling was observed in serotonin concentrations at 6 h following LPS and saline injection with a concomitant increase in the ratio of 5-hydroxyindoleacetic acid:serotonin. In the second experiment, hypothalamic monoamines were sampled before and at 3, 6, 9, 12, and 24 h after injection with LPS or saline. Significant increases from pre-injection levels were observed in the ratio 5-hydroxyindoleacetic acid:serotonin at 9, 12, and 24 h after injection, but no differences were detected between LPS- and saline-injected fish. These results support a model linking serotonergic system activation following handling stress, but no correlations with the sustained elevations of plasma cortisol associated with inflammatory challenge were observed.  相似文献   

11.
Herbivorous grass carp (Ctenopharyngodon idella) has been reported to exhibit low capacity to utilize high dietary lipid, but different lipid sources might affect this limited capacity. In order to compare the effects of different lipid sources with different lipid levels, juvenile grass carp were fed one of nine diets containing three oils [lard, plant oil mixed by maize and linseed oil, and n‐3 high unsaturated fatty acid‐enriched (HUFA‐enriched) fish oil] at three lipid levels (20, 60 and 100 g kg?1 dry diet) for 8 weeks. Decreased feed intake, poor growth performance, hepatic pathology and higher blood lipid peroxidation were found in 60 and 100 g kg?1 fish oil groups. Conversely, in lard and plant oil groups, even at 100 g kg?1 dietary lipid level, feed intake and growth performance did not decrease, despite histological observation revealed hepatic pathology in these groups. Plasma triglyceride and cholesterol contents increased significantly in all 100 g kg?1 dietary lipid groups. In the comparison of hepatic FA β‐oxidation among three oil groups at 60 g kg?1 dietary lipid level, impaired mitochondrial and peroxisomal FA oxidation capacity was observed in fish oil group. The results confirmed the relatively low capacity of grass carp to utilize high dietary lipid, and furthermore excess HUFA intake will result in more serious adverse effects than other FA.  相似文献   

12.
This study was designed to investigate effects of dietary Chlorella meal (CM) additive on growth performance, immune responses and appetite regulation of juvenile crucian carp Carassius auratus (initial body weight: 1.27 ± 0.03 g). Four experimental diets were formulated to contain 0% (CM0), 1% (CM1), 2% (CM2) and 4% Chlorella meal (CM4), respectively. Each diet was randomly assigned to triplicate groups with 40 juvenile fish per fibreglass tank for 8 weeks. Weight gain rate, specific growth rate and feed intake increased with increasing dietary CM levels. In contrast, FCR (feed conversion rate) declined with dietary CM levels. No significant differences were observed in moisture, crude protein, crude lipid and ash contents of muscle and liver tissues. Dietary CM addition increased activities of acid and alkaline phosphatase in liver and kidney. Dietary CM up‐regulated the mRNA expression levels of NKEF‐B, MCHII and IgM in kidney, and increased the mRNA levels of NPY and agouti gene‐related protein in the brain, but down‐regulated mRNA levels of MC4R, LEP, LEPR, CART1, CART2 and CCK8 genes. Based on these observations above, this study indicated that dietary CM additive increased growth performance, immune responses and appetite of crucian carp. The results, for the first time, demonstrate a role for the central nervous system in the control of food intake in fish fed dietary Chlorella meal.  相似文献   

13.
In general, the effects of dietary fatty acids (FA) on sperm quality have received less attention than egg quality, and were never studied in perch. This study investigated the effects of dietary FAs on the quality and chemical composition of sperm in Eurasian perch (Perca fluviatilis). Two experimental diets containing 16% lipids and 45% proteins were compared. The n‐3/n‐6 ratios tested were 0.2 for diet 1 (D1) and 7.0 for diet 2 (D2). No significant effects of the n‐3/n‐6 ratio were observed on the sperm characteristics, either in terms of the sperm volume (around 1.2 mL) and density, spermatozoa motility (94%) and velocity, or the sperm osmolality. All these parameters corresponded to semen of good quality in Eurasian perch. Interestingly, both the FA composition and the lipid class profile of the semen were correlated to the tested diet. However, basal levels of certain highly unsaturated FAs such as eicosapentaenoic acid, 20:5 n‐3 and docosahexaenoic acid, 22:6 n‐3, were maintained in the sperm irrespective of the diet tested. Perch semen was characterized by high levels of cholesterol, phosphatidylethanolamine and phosphatidylcholine. In conclusion, the dietary n‐3/n‐6 ratio affects the lipid composition of perch semen but not the indicators of sperm quality.  相似文献   

14.
In Eurasian perch (Perca fluviatilis), the variability in spawning quality is a major limiting factor for successful production, especially when breeders are fed with an artificial diet. The influence of the dietary DHA/EPA/AA ratio on the egg and larval quality and on the fatty acid and lipid class composition of eggs has been investigated in perch broodstock. Two experimental diets (16% lipids) with two different DHA/EPA/AA ratios, D1 (3/2/2) and D2 (23/9/1), were compared with a natural diet consisting of cultured carp juveniles, CC (10/10/1) and with a commercial diet for salmonids, CDS (14/16/1). Percentages of fertilization and hatching were comparable between fish fed D1, D2 and CC, with the highest hatching rate observed for D1 (63.5 ± 3.8%). These diets supported better values than the CDS. Larval survival and TL50 observed after osmotic stress were higher for the D1 group, followed by larvae produced by fish fed D2 and CC. Larvae from fish fed D1, D2 and CC were significantly more robust than larvae from the CDS group. Differences were observed regarding the fatty acid (FA) profile in the eggs, which was related to the dietary FA composition. The results indicate that a ratio of 3/2/2 seemed to be effective for obtaining eggs and larvae of good quality.  相似文献   

15.
In the present paper, the results of a study on changes in the proximate and amino acid composition of the eggs and larvae of two Australian native Percichthyid fish, Macquarie perch, Macquaria australasica Cuvier, and trout cod, Maccullochella macquarensis (Cuvier), are presented. The stages of development studied were unfertilized and fertilized eggs, newly hatched larvae, and post-yolk-sac larvae (in Macquarie perch only). In Macquarie perch, significant changes in moisture content occurred throughout development, but this was not so in trout cod. The protein content (per cent dry weight) in Macquarie perch larvae only decreased significantly after hatching (P < 0.05). On the other hand, the total lipid (by dry weight) increased significantly during this transformation (P < 0.05), and decreased significantly in yolk-sac-resorbed larvae. In trout cod, the protein and lipid content did not change significantly up to hatching. The ash content increased significantly in newly hatched and yolk-sac-resorbed larvae of both species. The total amino acid contents of unfertilized eggs, fertilized eggs, newly hatched larvae and yolk-sac-resorbed larvae of Macquarie perch and trout cod were 5752, 4652, 3696 and 2723 μmol g?1 (dry weight), and 4688. 3448 and 2329 μmol g?1, respectively. In the amino acid pool in Macquarie perch, the essential amino acids (EAAs) leucine, isoleucine and valine, and the non-essential amino acids (NEAAs) alanine, aspargine and glutamate occurred in the greatest quantities in non-fertilized eggs, and the cysteine content was the smallest. In Macquarie perch, five out of nine EAAs (i.e. isoleucine, leucine, lysine, threonine and valine) and six out of eight NEAAs (i.e. alanine, asparagine, glutamate, glycine, proline and serine) decreased significantly (P < 0.05) from one developmental stage to the other. In trout cod, all the EAAs, barring lysine and all the NEAAs decreased significantly with development.  相似文献   

16.
The efficiency of the rotifer Brachionus calyciflorus Pallas as a nutritional source for rearing larvae was studied in a coldwater cyprinid, the gudgeon Gobio gobio (L.), and in a percid, the perch Perca fluviatilis L., through their composition in fatty acids. Rotifer intake affected the fatty acid profiles of the larvae significantly, with an especially remarkable presence of the linoleic family. In gudgeon fed with rotifers, the polyunsaturated fatty acids (PUFA) reached 10.98% of the dry weight of the sample. This rate was highly influenced by the presence of the acids C18:2n-6 and C22:6n-3 which represented 66% of the total PUFA. In perch fed exclusively with rotifers, the PUFA represented 7.27% of the dry weight. In both cases, the ratio n-3/n–6 decreased by 75% and 73% after 10 days of feeding with B. calyciflorus. This variation was probably due to the exogenous supply in acids of the linoleic family through the rotifers and to the fact that these two species of fish seem to favour the mobilization of the n-3 PUFA such as C22:6n-3 for growth and survival. Moreover, with the utilization of rotifers. the reactions of elongation and desaturation from the C18:2n-6 and C18:1n-9 seemed to be much more important in the larvae. Lastly, the transition from a diet based on rotifers to one made up exclusively of frozen Artemia nauplii led to a significant reduction of fatty acids in fish. It reached 60.2% and 26.5% of the total fatty acids in the gudgeon and perch, respectively, and was observed especially at the level of the PUFA. On the other hand, a slight increase of the ratio n-3/n-6 was pointed out in the perch fed a mixed diet (co-feeding with rotifers and dry food), a phenomenon probably due to the reduction of C18:2n-6 in the larvae.  相似文献   

17.
To investigate the effects of dietary vitamin C on growth, flesh quality and antioxidant capacity of juvenile golden pompano Trachinotus ovatus, a 56‐day feeding trial with five graded levels of dietary VC (D1: 11.69, D2: 34.89, D3: 59.10, D4: 114.26 and D5: 227.93 mg VC per kg of diet) was performed on 375 fish (triplicate groups of 25 fish per diet, initial weight 13.57 ± 0.09 g). Results showed that fish of D3 group exhibited the maximum specific growth rate (SGR) and the highest liver enzymatic activities of catalase (CAT) and glutathione peroxidase (GSH‐PX), which were consistent with the expression levels of cat and gsh‐px. Besides, the D3 group also showed higher contents of protein and lipid, and lower cooking loss, drip loss and malondialdehyde content in muscle than D1 group. The docosahexaenoic acid proportion in muscle increased with increasing dietary VC levels. Furthermore, the lowest expression levels of carnitine palmitoyltransferase1 (cpt1) and peroxisome proliferator‐activated receptor α (pparα) were detected in livers of D3 group. The optimum dietary VC level was 49.73 mg/kg from the broken‐line analysis based on the SGR, in which better growth performance, antioxidative ability and flesh quality were observed in T. ovatus juveniles.  相似文献   

18.
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19.
Ferulic acid (FA) derivative was synthesized by modifying the functional groups of FA as dietary additive in the feeding of Genetically Improved Farmed Tilapia (GIFT) juveniles. Structural confirmation of this compound was based on IR, 1H and 13C NMR techniques. This study was conducted to evaluate the effects of dietary FA derivative supplementation on growth performance, antioxidant status and serum biochemical parameters of GIFT juveniles compared with that of FA. A total of 675 fish with an average initial weight of 10.73 ± 0.40 g were fed nine diets supplemented with 0, 0.26, 0.52, 1.04 and 2.08 mmol kg?1 FA, or 0.26, 0.52, 1.04 and 2.08 mmol kg?1 FA derivative. Each diet was assigned to three replicate groups of 25 experimental tilapia for 56 days. Weight gain (WG) in groups of fish fed FA derivative was much higher than that of fish fed FA diet (P < 0.05). The antioxidant enzyme activities (SOD, CAT and GPx) in serum and liver of tilapia fed the FA derivative diets were significantly higher, while the malondialdehyde values were significantly lower than those of the fish fed the FA diets (P < 0.05). The serum biochemical parameters of GIFT were significantly improved by the FA derivative supplement. Moreover, feed conversion ratio, hepatosomatic index and viscerosomatic index were significantly decreased in fish fed FA or FA derivative diet at 0.52 mmol kg?1 feed (P < 0.05). The investigation on the semisynthetic FA derivative provides a new way for developing safe and efficient feed additives.  相似文献   

20.
Infestations of parasitic monogenean trematodes (Lepidotrema bidyana and Gyrodactylus sp.) on freshwater silver perch (Bidyanus bidyanus Mitchell) in earthen ponds were treated with formalin (37% formaldehyde). Concentrations of 30 and 40 mg L?1 formalin were effective, but fish in ponds treated with 20 or 25 mg L?1 remained infested. At temperatures of 24.1–26.9°C, concentrations of 30 or 40 mg L?1 formalin caused dissolved oxygen (DO) to decline from 10.1–11.9 to 3.0–3.3 and 1.2–1.7 mg L?1, respectively, within 36–42 h of treatment. In addition, pH declined from 7.2–8.4 to 6.3–6.7, within 36 h and turbidity decreased over 48 h. In the ponds where DO was 1.2–1.7 mg L?1, silver perch showed signs of severe stress, but continuous aeration (10 hp ha?1) for 3 days and inflow of well‐oxygenated water for 6–8 h prevented mortalities. At temperatures of 13.2–15.7°C, concentrations of 30 or 40 mg L?1 formalin caused DO to decline from 9.0–10.0 to 6.0–8.1 mg L?1 and pH from 7.0–7.3 to 5.9–6.6 within 72 h. Total ammonia‐nitrogen increased over 72 h in ponds treated with 30 or 40 mg L?1 formalin. Fish became re‐infested with L. bidyana in all ponds within 30 days of treatment. A concentration of 30 mg L?1 formalin is recommended as a treatment for monogeneans on silver perch in ponds, but aeration is necessary to maintain adequate water quality at higher temperatures.  相似文献   

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