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A feeding experiment was conducted to study the effects of dietary lipid sources and L-carnitine on the growth performance, body component, muscle fatty acid composition, and antioxidant enzyme ability of average weight of 0.28 g dog conch larvae, Laevistrombus canarium. Three sources of lipid: fish oil, soybean oil, and beef tallow were tested in combination with two levels (0 and 0.5%) of L-carnitine. The dog conch larvae fed diets containing fish oil with L-carnitine supplementation exhibited the highest weight gain. After air exposure challenge, the liver tissue of dog conch fed the diets containing soybean oil and beef tallow without supplemented L-carnitine had lower levels of superoxide dismutase (SOD, U min−1), phenoloxidase (PO, U min−1), and glutathione peroxidase (GPx, mU/mL) activity. The activity of SOD, PO, and GPx of dog conch larvae increased with increasing levels of dietary L-carnitine. In particular, dog conch larvae fed the diet containing fish oil supplemented with L-carnitine exhibited significantly (P < 0.05) enhanced antioxidant responses. The thiobarbituric acid reactive substances (TBARS) in the muscle tissue of dog conch larvae fed the diet containing fish oil without L-carnitine supplementation showed significantly (P < 0.05) higher activity. It was concluded that dietary administration of L-carnitine can enhance resistance against beta-oxidation, and the administration of fish oil in the diet was the best strategy to promote growth due to high nutritional availability. [ABSTRACT FROM AUTHOR]

This study evaluated the anaesthetic and sedative effects of eugenol applied on yellow catfish (Pelteobagrus fulvidraco). In the anaesthesia induction and recovery experiment, fish were treated with five concentrations of eugenol (0, 15, 20, 25 and 30 mg/L), respectively, and in the transportation experiment, fish treated with 10 mg/L eugenol were evaluated after 12 h simulated transportation. Induction and recovery time were recorded. The induction time shortened with the increasing eugenol concentration, whereas the recovery time prolonged with the increasing eugenol concentration. The effective concentration of eugenol for short‐term anaesthesia induction was between 25 and 30 mg/L. The post‐transportation survival rate of yellow catfish was 100%. The content of ammonia nitrogen in the eugenol group was lower (p < 0.05). Compared with the control group, yellow catfish in the anaesthetized transportation group showed a significant decrease in blood cortisol levels (p < 0.05), whereas the levels of glucose and lysozyme significantly increased (p < 0.05). Both hsp70 and hsp90 mRNA expression in the liver of anaesthetized yellow catfish were found to significantly upregulate after transportation (p < 0.05). In summary, eugenol was an effective anaesthetic for yellow catfish. For short‐term anaesthesia, the recommended concentration is 25–30 mg/L and for long‐time transportation, the appropriate concentration is 10 mg/L in order to reduce stress response of fish. [ABSTRACT FROM AUTHOR]

The present study was designed to examine the physiological responses of juvenile managua cichlid, Cichlasoma managuense under short‐term salinity stress, that is transferring C. managuense from freshwater to brackish water of salinity 0 (control group), 3‰, 6‰, 9‰, 12‰ or 15‰ for 48, 96, 144 and 192 hr respectively. The results showed that gill Na+/K+‐ATPase (NKA) activity revealed a decreased (48 hr), increased (96 hr) and then slightly decreased (144 hr, 192 hr) response with increasing salinity and the lowest NKA level was consistently detected at 9‰ salinity treatment; gill Ca2+/Mg2+‐ATPase (CMA) activities in all salinity treatments were significantly higher than that of the control group (p <.05) before 144 hr; the RNA/DNA ratio was significantly reduced when exposed to high salinities (≥9‰), suggesting growth inhibition; serum cortisol level gradually decreased at low salinities (up to 6‰) but dramatically increased at high salinities of 12‰ and 15‰; and both serum glucose/lactic acid levels and heat shock protein 90 (HSP90) level in liver/muscle were decreased at the salinity between 9‰ and 6‰ but increased at the salinity between 12‰ and 15‰, which was a U‐shape response curve. Taken together, our data suggest that C. managuense can adapt well at salinity up to 0‰–9‰ and high salinity may cause detrimental effects. [ABSTRACT FROM AUTHOR]

Caspian roach (Rutilus rutilus caspicus), a spring spawning teleost, were subjected to various photoperiod and temperature regimes to study the feasibility of shifting the timing of spawning for artificial propagation purposes. A total of 650 female reproductively mature R. rutilus caspicus were subjected to different photoperiod and temperature regimes including four light regimes (natural light (NL), 16 hr of light (L):8 hr of darkness (D), 9L:15D, 11L:13D), each affected by three temperature regimes (14, 20 and 24°C) for 70 days. Five fish per tank were randomly sampled on Feb. 10, Feb. 20, March 28, April 15 and April 30 (natural spawning time). Ovarian tissue sections were studied using light microscope and transmission electron microscope (TEM). The levels of 17‐β estradiol (E2) and 17α‐hydroxyprogesterone (OHP) were also measured in the serum samples. In late winter (March 28th), the gonadal maturation and spawning were accelerated in fish treated with the long day length (16L/8D) and warm temperature (20°C). While, the maturation of oocytes and spawning delayed in fish exposed to low temperature (14°C) and short day length (9L/15D and 11L/13D). Photoperiod seems to play a more important role in the ovarian development of the R. rutilus caspicus compared to temperature; since even among the fish treated with the lowest temperature (14°C), those exposed to a longer day length (16L/8D), matured and spawned earlier than the others. Considering that the earliest spawning occurred in R. rutilus caspicus treated with 16L/8D at 20°C and the latest spawning occurred in fish exposed to low temperature and short photoperiod, it can be concluded that temperature and photoperiod play an important role in accelerating oocyte maturation and spawning. [ABSTRACT FROM AUTHOR]

The differences in hatching rate, incubation period, viability of 24 h posthatch larvae and total mortality rate were tested through one-way ANOVA, followed by Tukey's I post hoc i test ( I p i < .05). The relationship between temperature and hatching rate, temperature and viability of 24hpost-hatch larvae, and temperature and total mortality rate was all modelled by a quadratic equation ( I r i SP 2 sp > .90; Figure). According to the total hatching rate observed, viability of 24 h posthatch larvae and total mortality rate, we can concluded that the optimal conditions of temperature for incubation eggs ranged from 24 to 28°C. [Extracted from the article]

The mass mortalities of sea cucumber Apostichpous japonicus have prevailed in northern China, mainly attributing to the emergence of extreme environmental conditions, that is hyperthermia and hyposalinity. The high‐quality sea cucumber seedlings appear to possess more robust resistance to adverse conditions. There are usually indoor‐ and outdoor‐cultured seedlings in industrial production of sea cucumbers. Although the outdoor‐cultured sea cucumbers are practically considered to be more strong and robust, the effective evaluation approach to distinguish these seedlings has been scarce. The current study compared survival and immune performances of indoor‐ and outdoor‐cultured A. japonicus under combined exogenous stressors, that is hyperthermia and hyposalinity. Results based on secondary stress induction revealed that the activities of immune enzymes and levels of catecholamines in body wall of outdoor‐cultured seedlings were prominently higher than those of indoor‐cultured seedlings recovered for 0–72 hr following sublethal stress (30°C and 25 psu of salinity). The opposite case occurred on immune enzymes in coelomic fluid of the two sources of seedlings except for myeloperoxidase. Importantly, the outdoor‐cultured seedlings, which were recovered for 72 hr after sublethal stress, exhibited a 93% of cumulative survival rate following 7 days of recovery after lethal stress (33°C and 20 psu of salinity), 27% higher than the indoor‐cultured seedlings. Collectively, the outdoor‐cultured A. japonicus seedlings showed more superior quality than the hatchery‐produced seedlings in terms of survival and immune performance. These findings provide practically useful information towards quality distinction of the indoor‐ and outdoor‐cultured sea cucumbers, which could benefit the aquaculture industry to obtain high‐quality seedlings. [ABSTRACT FROM AUTHOR]

Abstract: This study seeks to identify the optimal combination of temperature and salinity for the embryo development of the hybrid groupers, Epinephelus fuscoguttatus (♀) × Epinephelus polyphekadion (♂), using the central composite design and response surface methodology. Results have shown that the low hatching rates of fertilized eggs and high deformity rates of larvae were the result of lower or higher temperature/salinity levels. The linear effects of temperature and salinity were significant in both hatching rates and deformity rates (p < .01). Similar results were observed in the quadratic effects of temperature and salinity (p < .01). Effects of temperature were positively related to salinity effects (p < .05). Salinity effects were more remarkable than temperature on hatching rates, but not the same on deformity rates. Model equations were established for temperature and salinity effects on hatching rates and deformity rates. A high coefficient of determination (R2 > .97) was found for the adequacy and predictive capability of model equations, indicating that these models can be applied to prediction. The optimal combination of temperature and salinity was 27.58°C/30.94, which was derived from the statistical optimization approach. In this condition, the hatching rate was the highest at 85.73%, and the deformity rate was the lowest at 5.96%, with a high desirability function of 0.957. The results of this study can be applied to improve hatching and decrease deformity in future cultures of hybrid groupers. [ABSTRACT FROM AUTHOR]

In the view of an urgent necessity to improve the quantity and the quality of farmed fish species, there is a strong need to improve our basic knowledge on the effects of first feeding during the developmental stages of fish larvae. High mortality, mainly due to food deprivation or inappropriate food quality, has been observed in many larval fish species, but knowledge about the morphological, biochemical and molecular processes related to this topic is still poorly understood. The understanding of the early larval ontogeny as well as the larval nutritional requirements and the molecular and cellular mechanisms elicited by fish larvae during food deprivation and starvation are thus of primary importance. At this regard, this study investigates, in Dover sole larvae, the effects of starvation and starving/re-feeding procedures at a morphological, histological, biochemical and molecular level. The results evidenced that starved larvae progressively decrease in growth, lipid content, affected their gastrointestinal tract and muscle development and increased cortisol and heat shock protein 70 levels. On the contrary, starved and re-fed larvae showed, after the restoration of a favourable feeding condition, a compensatory growth. In conclusion, this is the first study analysing through a multidisciplinary approach the effects of food deprivation on the development of an important economic species, the Dover sole. [ABSTRACT FROM AUTHOR]

An investigation on the physiological responses and HSP70 expression under cold stress was conducted on Genetically Improved Farmed Tilapia ( GIFT) strain of Nile tilapia ( Oreochromis niloticus). Tilapia were acclimated at 28°C as control and then the water temperature was reduced from 28°C to 15°C at a rate of 1°C h−1, and serum biochemical indices, antioxidant enzymes and expression of HSP70 m RNA were analysed on days 0, 0.5, 1, 2, 3 and 5 after exposure to 15°C. The concentration of serum K, Na, Cl and Ca concentration showed instability during cold stress. Glucose rapidly increased on day 0 followed by a declining trend. Triglyceride, cholesterol, low density lipoprotein-cholesterol signifi-cantly decreased and high density lipoprotein-cholesterol showed instability during cold stress. Aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase activities were prominently elevated under cold stress. Superoxide dismutase and catalase activities showed a remarkable rise on day 0.5 under cold stress, and gradually decreased thereafter. HSP70 m RNA level significantly increased both in liver and muscle under cold stress, especially on days 0.5 and 1. These results suggest that cold influences several physiological responses of tilapia, and the cold resistance and cold tolerance of tilapia will benefit from the enhancement of antioxidant enzymes activities and upregulated HSP70 m RNA expression. [ABSTRACT FROM AUTHOR]