Devising optimum feeding regimes and temperatures for the warmwater culture of eel,Anguilla anguilla L.*

Abstract. This paper describes feeding experiments conducted with small eels under holding conditions and temperatures designed to mimic those on the farm. It was shown that at temperatures up to 16°C highest daily consumptions occur with frequent feeding. This is because gut passage is slowed and limits consumption at these temperatures. At higher temperatures feed consumption and conversion can be increased by feeding meals at a defined optimum frequency which was shown to rise with temperature. This optimum frequency of feeding is associated with lowered activity levels which spare energy for growth. The underlying factor is a preference for meals at a size and feeding interval corresponding with the capacity and emptying of the stomach. Optimum conditions for growth are shown to occur at 26.5°C with maximum consumptions at a feeding frequency of either three or four times per 24-h day. This optimum temperature is shown to be lowered as daily feed intake is reduced.     

Effects of temperature on hatchability, development and growth of eggs and yolksac fry of Oreochromis mossambicus (Peters) under artificial incubation

Abstract. The eggs and yolk sac fry of the mouth brooding tilapia. Oreochromis mossambicus (Peters), were artificially reared in an experimental hatchery system at different temperatures. The hatchability, embryonic development of eggs and growth of yolk sac fry were studied under controlled conditions. It was shown that the upper lethal temperature for O. mossambicus eggs was above 40°C and the lower lethal temperature between 11°C and 17°C. For yolk sac fry these values lay between 34 and 40°C and 17 and 20°C respectively. Fry survival between 24·3 and 34·0°C was near to 100% while al 20°C it was less than 60%. The somatic growth rates of fry at temperature between 20 and 34·5°C up to 10 days post hatch are presented and were found to differ significantly. At 34·6°C a negative SGR was recorded during the period 6–9 days post hatching, but, during the first 6 days, the SGR at this temperature was more than four times higher than at 20°C. At the elevated temperatures, the utilization of yolk is faster and the loss of weight observed was due to starvation. This should be taken into account when incubating under artificial rearing condition so that initiation of exogenous feeding is timed most appropriately.     

Effect of feeding regime and temperature on ongrowing results of pikeperch (Sander lucioperca L.)

This study aimed to determine the effect of feeding rates and water temperatures on the growth, feed utilization and size heterogeneity changes in subadult pikeperch. Fish with an average weight of 84±19 g were fed with a commercial trout diet for 18 weeks at a water temperature of 20 °C and 25 °C. Four feeding rates (PSFR) were predicted at both temperatures, which corresponded to 1.0%, 1.25%, 1.50% and 2.0% of body weight per day (bw day⁻¹) for the first, and to 0.8%, 1.0%, 1.2% and 1.4% of bw day⁻¹ for the second 9 weeks respectively. At the end of the experiment, the individual weight averaged 273±82 g. Pikeperch showed a better growth rate [specific growth rate (SGR)] and apparent feed conversion rates (AFCR) at the higher temperature. Thermal-unit growth coefficient (TGC) was better at the lower temperature. The values of SGR, TGC and AFCR significantly increased with increasing PSFR at both temperatures. The values of TGC plotted against the computed feeding rates allowed estimation of the maximum feeding rates (1.25% and 1.15% of bw day⁻¹ for pikeperch of 150–180 g at 25 and 20 °C respectively). Size heterogeneity changes were affected neither by the feeding rate nor by temperature.     

Survival and growth of larval and juvenile tench, Tinca tinca L., fed different diets under controlled conditions

Abstract. Tench, Tinca tinca L., larvae were reared under controlled conditions at water temperatures of 28°C and 31°C during a 15-day period. Feeding with exclusively live Artemia nauplii gave best results, irrespective of rearing temperature (total length 13·6mm; average weight 31 mg; survival rate 83–85%). High survival rates of 81–88% were found also in all groups fed mixed diets, whereas growth rate of tench larvae was significantly influenced by the frequency of supplemental feeding with Artemia. When applied alone, the tested carp starter feed turned out to be insufficient for rearing the larval tench.     

Determination of the optimal water temperature for the culture of juvenile dusky kob Argyrosomus japonicus Temminck and Schlegel 1843

The effects of temperature on growth, food-conversion ratio (FCR) and feeding intensity of juvenile dusky kob Argyrosomus japonicus (23.7±2.6 g fish⁻¹) were assessed over the temperature range 17.5–28.5 °C in a 42-day growth trial. Growth increased with increasing temperature up to an optimum after which it declined. Specific growth rates were 2.05% and 1.2% day⁻¹ for the fastest (25.3 °C) and the slowest (17.5 °C) treatments respectively. Food-conversion ratio peaked at a lower temperature than growth. Optimal (0.72 kg kg gain⁻¹) and least efficient (1.40 kg kg gain⁻¹) FCR were found at 21.7 and 17.5 °C respectively. Feeding intensity was linearly related to temperature within the range of 17.5–28.5 °C. These results corresponded to the thermal preference (25–26.4 °C) and natural temperature distribution (12–28 °C) of South African dusky kob. Determination of the temperature range that does not limit growth is a prerequisite to assess the relationship between growth and environmental variables such as light intensity, feeding regime and stocking density. Consequently, experiments to determine the effects of these environmental variables on growth and aquaculture potential of dusky kob should be conducted at 24–26 °C.     

Effect of number of meals and frequency of feeding on voluntary feed intake of Colossoma macropomum (Cuvier)

Juvenile, 0.87 g Colossoma macropomum (Cuvier) were submitted to different ad libitum feeding regimes. Feeding frequency ranged from one to five meals per day and intervals between meals from 3 h to 24 h. Higher feeding frequencies resulted in higher feed uptake, a higher growth rate and a decreased feed utilization efficiency. Feed consumption was lower at 0700 h than at 1900 h. The amount of feed from different meals persisting in the digestive tract was determined with chromic-oxide-marked feed. This method revealed that with ad libitum feeding, about 21% of the feed remained uneaten. Feed losses did not differ significantly between feeding regimes. Feed accumulated in the digestive tract in the morning and early afternoon. In the late afternoon most feed rests disappeared from the digestive tract and feed consumption increased. It is suggested that feed uptake and growth of C. macropomum can be improved by extending the feeding period after 1900 h.     

Growth and feeding responses of a hatchery population of brown trout (Salmo trutta L.) at low temperatures

Abstract— Feed intake, specific growth rate and changes in body composition were studied in age 1+ (140-190 g) brown trout ( Salmo trutta L.) reared at three temperatures (2, 4 and 6°C) under continuous light conditions. Feed in take increased from 35.7 kJ-kg⁻¹.day⁻¹ at 2°C to 95.7 kJ-kg⁻¹-day⁻¹ at 6°C, and the growth rate increased from 0.19%-day⁻¹ to 0.42%-day⁻¹ over the same temperature range. The estimated lower temperature limits for feeding and growth were slightly above 0°C. For all groups of fish, the majority (about 75%) of the weight gain comprised water and protein, but lipid deposition tended to increase with increasing temperature. The deposition of lipid accounted for about 50% of the body energy gain at all temperatures.     

投喂频率对尼罗系吉富罗非鱼幼鱼胃排空、生长性能和体组成的影响

通过胃排空试验与养殖试验研究了不同投喂频率对尼罗系吉富罗非鱼幼鱼的胃排空、生长性能以及体组成的影响.在试验开始时,观测尼罗系吉富罗非鱼幼鱼的胃内饲料排空情况,胃排空试验结果表明,胃排空率的最佳描述为平方根函数,胃内饲料在饱食投喂后15 h左右完全排空,达到投喂前水平,80％胃排空为9h,也就是投喂后大约9h恢复食欲.360尾试验鱼(初始体质量3.72 g)以不同的投喂频率(1d4次、1d3次、1d2次、2d4次、2d3次、2d2次)分组,每组设立3个平行组,随机养殖于18个网箱中,每箱养殖20尾鱼,按饱食量投饲膨化饲料.养殖期为6周.尼罗系吉富罗非鱼幼鱼在投喂频率为1d4次、1d3次和1d2次时特定生长率和饲料效率显著高于投喂频率为2d4次、2d3次和2d2次时(P＜0.05)；投喂频率为1d2次、2d4次、2d3次和2d2次时其摄食量显著低于1d4次和1d3次时(P＜0.05).随着投喂频率降低,鱼体水分含量逐步上升,脂肪和蛋白质含量逐步下降,其中1d4次、1d3次组鱼与2d2次组鱼有显著性差异(P＜0.05).各投喂频率组间的肝体指数无显著性差异(P＞0.05).3.7～48.0 g尼罗系吉富罗非鱼幼鱼的适宜投喂频率为1d2次,较2d2次、2d3次和2d4次时明显提高了生长速度和饲料效率,较1d3次、1d4次摄食量显著降低.2种试验结果较为一致.     

Effects of body size and water temperature on food consumption and growth in the sea cucumber Apostichopus japonicus (Selenka) with special reference to aestivation

To investigate the effects of body size and water temperature on feeding and growth in the sea cucumber Apostichopus japonicus (Selenka), the maximum rate of food consumption in terms of energy (C_maxe; J day^?1) and the specific growth rate in terms of energy (SGRe; % day^?1) in animals of three body sizes (mean±SE) – large (134.0±3.5 g), medium (73.6±2.2 g) and small (36.5±1.2 g) – were determined at water temperatures of 10, 15, 20, 25 and 30°C. Maximum rate of food consumption in terms of energy increased and SGRe decreased with increasing body weight at 10, 15 and 20°C. This trend, however, was not apparent at 25 and 30°C, which could be influenced by aestivation. High water temperatures (above 20°C) were disadvantageous to feeding and growth of this animal; SGRe of A. japonicus during aestivation was negative. The optimum temperatures for food consumption and for growth were similar and were between 14 and 15°C, and body size seemed to have a slight effect on the optimal temperature for food consumption or growth. Because aestivation of A. japonicus was temperature dependent, the present paper also documented the threshold temperatures to aestivation as indicated by feeding cessation. Deduced from daily food consumption of individuals, the threshold temperature to aestivation for large and medium animals (73.3–139.3 g) was 24.5?25.5°C, while that for small animals (28.9–40.7 g) was between 25.5 and 30.5°C. These values are higher than previous reports; differences in sign of aestivation, experimental condition and dwelling district of test animals could be the reasons.     

Effects of Feeding Rate and Feeding Frequency on Survival, Growth, and Body Composition of Ayu Post-Larvae Plecoglossus altivelis

The effects of feeding rate and feeding frequency on survival, growth and body composition of ayu post‐larvae (0.15 g in body weight and 3.5 cm in total length) were investigated in this study. A factorial experimental design of two feeding rates (3 and 6% of body weight of fish per meal) five feeding frequencies (one meal in 2 d, one meal a day, two meals a day, four meals a day, and six meals a day) with three replicates was used. Survival of ayu post‐larvae was significantly (P 0.05) affected by feeding frequency but not by feeding rate. Survival of ayu improved linearly with feeding frequency at both feeding rates. Weight and length gains and specific growth rate (SGR) of ayu was significantly (P 0.05) affected by feeding frequency but not by feeding rate, with weight and length gains and SGR linearly elevated with increasing feeding frequency at both feeding rates. The greatest weight and length gains were observed in fish receiving six meals daily at both feeding rates; however, no significant difference in weight gain was observed among two, four, and six meals a day, or in length gain between four and six meals a day. Feed efficiency ratio (FER) was significantly (P 0.05) affected by both feeding rate and feeding frequency. FER linearly decreased with feeding frequency at both feeding rates or feeding rate in the same feeding frequency. When the total daily amount of feed supply was constant with various feeding frequencies at different feeding rates (one meal a day at 3% feeding rate and one meal in 2 d at 6% feeding rate, two meals a day at 3% feeding rate and one meal a day at 6% feeding rate, or four meals a day at 3% feeding rate and two meals a day at 6% feeding rate), improvement in survival, weight and length gains, and SGR was observed in fish with higher feeding frequency at lower feeding rate. Moisture, protein, and lipid content of fish were not significantly (P > 0.05) affected by either feeding rate or feeding frequency. However, lipid content of ayu linearly increased with feeding frequency at 6% feeding rate. The highest body lipid content was observed in fish receiving six meals daily at both feeding rates. Ash content of fish was significantly (P 0.05) affected by feeding frequency but not by feeding rate. Based on performance of ayu, it can be concluded that optimum feeding rate and feeding frequency for ayu post‐larvae (an initial weight of 0.15 g) were 3% per meal and four meals a day, respectively, under these experimental conditions.     

Effect of water temperature on the growth performance and digestive enzyme activities of Chinese longsnout catfish (Leiocassis longirostris Günther)

The present study was carried out to investigate the influence of water temperature on the growth performance and digestive enzyme (pepsin, trypsin and lipase) activities of Chinese longsnout catfish. Triplicate groups of Chinese longsnout catfish (35.6±0.48 g, mean±SE) were reared at different water temperatures (20, 24, 28 and 32 °C). The feeding rate (FR), specific growth rate (SGR) and feed efficiency ratio (FER) were significantly affected by water temperatures and regression relationships between water temperature and FI, SGR as well as FER were expressed as FR=−0.016 T ²+0.91 T −10.88 ( n =12, R ²=0.8752), SGR=−0.026 T ²+1.39 T −17.29 ( n =12, R ²=0.7599) and FER=−0.013 T ²+0.70 T −8.43 ( n =12, R ²=0.7272). Based on these, the optimum temperatures for FR, SGR and FER were 27.66, 26.69 and 26.44 °C respectively. The specific activities of digestive enzymes at 24 or 28 °C were significantly higher than that at 20 or 32 °C. In addition, there was a significant linear regression between FR or SGR and specific activities of pepsin and lipase, which indicated that pepsin and lipase played important roles in regulating growth through nutrient digestion in Chinese longsnout catfish.     

Upper lethal and rearing temperatures for juvenile common carp, Cyprinus carpio L., and silver carp, Hypophthalmichthys molitrix (Valenciennes)

Abstract. The ultimate upper lethal temperature (UULT) was 43.0 or 46.0°C for common carp and 43.5 or 46.5°C for silver carp, depending on the method of calculation. The influence of fish age on lethal temperature values was low. Using the relationship between the UULT and the optimum growth temperature the latter was calculated as being 38°C for common carp and 39°C for silver carp. No significant differences were found in survival of fish reared at lower and higher temperatures when proper food was used.     

Effects of dietary protein and lipid level, and water temperature, on the post-feeding oxygen consumption of Atlantic cod and haddock

Tank respirometry was used to study the interactive effects of protein:lipid level (55%:11% vs. 42%:16%; both diets isoenergetic) and temperature (11, 6 and 2 °C) on the magnitude and duration of specific dynamic action (SDA) in juvenile Atlantic cod and haddock. The protein:lipid level did not affect any measured variable. However, numerous temperature and species effects were observed. For example, although the maximum post-feeding oxygen consumption (30–50% above routine metabolic rate; RMR) and SDA duration (∼55–85 h; SDA_DUR) were not affected by temperature, SDA_DUR g⁻¹ of food increased from 11 to 2 °C (from ∼3 to 12 h g food⁻¹). While absolute SDA (mg O₂) decreased by ∼60–65% in cod and ∼75% in haddock from 11 to 2 °C, due to a concomitant decrease in food consumption from ∼2.0% to 0.6% body mass, SDA comprised between 3.3% and 5.2% of the dietary energy content at all temperatures. Finally, RMR at 11 and 2 °C and SDA_DUR at 2 °C were 25–35% and 25% greater in cod, respectively, as compared with haddock. These results suggest that feeding reduced protein diets at low water temperatures is unlikely to improve the growth of these species.     

Further clarification of winter energy and protein requirements at the optimum feeding frequency for yellowtail

SUMMARY: This is another report from a series of studies aimed at determining the energy and protein requirements based on the optimum feeding frequency of yellowtail during the winter season. Experiments were conducted at Mie and Oita Prefectures, Japan, employing extruded pellets of known digestible energy (DE) and digestible protein (DP) values. Four groups of fish were fed at frequencies of five, three, two, and one time(s) per week. The most efficient feed performance was obtained for the feeding frequenecy of three times per week. The DE and DP requirements calculated based on the feeding rate at this frequency were 38.7 kcal and 2.8 g/kgBW per day (14.3–17.3°C) in Mie and 30.4 kcal and 2.2 g/kgBW per day (13.8–17.5°C) in Oita, respectively. The present results and the observations on the changes of the contents in digestive tracts tallied with our previous work, confirming that the optimum feeding frequency was three times per week.     

Temperature requirements for seed germination and seedling growth of Zostera marina from central Japan

ABSTRACT:   The optimal water temperature in seed germination and the upper critical water temperature in seedling growth were determined for Zostera marina collected from Ise Bay, Japan. The relationship between the seed germination rates and seed storage period (0, 30 and 60 days at 0°C) was also examined. The optimal water temperature for seed germination was in the range from 10 to 15°C regardless of the storage periods, in which germination rates ranged from 35 to 57%. Seedlings grown from seed up to 10 cm in total length were cultured for 1 week under various water temperatures to measure their relative growth rates. The optimal water temperature in growth was in the range from 20 to 25°C; relative growth rates ranged from 2.0 to 2.6%. Seedlings could survive up to a water temperature of 28°C, but most seedlings withered at 29 or 30°C. The optimal water temperatures for seed germination and seedling growth were related to the seasonal changes of water temperature at the sampling site. Although seedlings were rarely observed in the field in summer, they can grow at temperatures as high as 28°C. Therefore, Z. marina may extend its distribution as far as where the summer water temperature is lower than 28°C.     

Response of Israeli carp, Cyprinus carpio L., to lysine supplementation of a practical ration at varying conditions of fish size, temperature, density and ration size

Abstract. Four feeding trials with Israeli carp, Cyprinus carpio L., were performed in cages or in ponds in order to investigate responses to lysine supplementation of low protein carp feeds under different practical conditions. In each of the trials one of the basic conditions was different: fish size—small (80–125g) or large (560g); temperature—22°C or 26°C; density—cages or ponds. In each trial 2–3 ration sizes × 2–3 lysine levels were tested. A basal diet of 25% protein and 1·35% lysine served for all the trials.
At low feeding levels, no responses to lysine supplements were found either at 22 ± 2°C or at 26 ± 2°C (0600 h) for all fish sizes. At higher feeding levels, at both temperatures, 0·5% lysine-HCl supplements to 1·7% total lysine yielded significant growth increases. Further supplements to 2·1% lysine (=8·4% of the protein) brought an additional response only from small fish of 90g in cages at the highest ration and temperature. In ponds at 26°C, the effects on small fish of 80g were smaller, probably due to available natural food. The reduction in lysine retention suggested that 1·7% lysine might have been adequate even at optimal conditions in ponds.     

Growth and oxygen consumption of the juvenile sea cucumber Apostichopus japonicus (Selenka) at constant and fluctuating water temperatures

The effects of thermal amplitudes of diel fluctuating temperature on growth and oxygen consumption of the juvenile sea cucumber Apostichopus japonicus (Selenka) were studied at the average temperatures of 15 and 18°C with three diel different fluctuating amplitudes of ±2, ±4 and ±6°C. The optimum thermal amplitudes for growth of the juvenile sea cucumber at the sizes of this experiment, at average temperatures of 15 and 18°C, were estimated to be ±1.38 and ±1.67°C respectively. In the constant temperature regimes, the growth rate at 15°C was higher than that at 18°C. However, the growth rate at 18±2°C was higher than that at 15±2°C. The results from this study suggested that fluctuating temperatures enhanced the optimum temperature for the growth of sea cucumbers compared with that at constant temperatures. Therefore, accurate predictions of the optimum temperature of sea cucumbers in the natural environment, in which water temperatures fluctuate daily and seasonally, should be made from data obtained at fluctuating temperatures.     

Effects of water temperature on early development of Japanese eel <Emphasis Type="Italic">Anguilla japonica</Emphasis>

ABSTRACT:   To determine an optimal temperature range for efficient production of healthy eel larvae Anguilla japonica , the effect of water temperature on hatching, survival, and deformity rates was examined. The early ontogeny of morphological features in this species by incubating eggs at five different temperatures (19, 22, 25, 28 and 31°C) was examined. Hatching occurred at 24, 28, 46 and 58 h after fertilization when incubated at 28, 25, 22 and 19°C, respectively; no eggs hatched at 31°C. The growth rate of prefeeding larvae increased as water temperature was elevated and acquisition of feeding ability was also accelerated at higher temperature. Significantly high hatching rates (76–86%, P  < 0.05) and survival rates (61–86%, P  < 0.05) were observed at relatively high temperatures (22–28°C). The deformities were 'open lower jaw', 'pericardial edema', and 'notochordal bending', in which the mouth was deformed with a downward projecting lower jaw, the pericardial cavity was swollen, and the notochord was bent or twisted to various degrees, respectively. Open lower jaw and pericardial edema were especially predominant at 19°C, with rates of 68 and 92%, respectively, compared with 31 and 10% at 25 and 28°C, respectively. The occurrence of notochordal bending was not affected by temperature. The optimal temperature for incubation and rearing A. japonica eggs and prefeeding larvae is approximately 25–28°C.     

Effects of constant and cyclical thermal regimes on growth and feeding of juvenile cutthroat trout of variable sizes

Abstract –  The effects of constant (12, 18, and 24 °C) and cyclical (daily variation of 15–21 and 12–24 °C) thermal regimes on the growth and feeding of Lahontan cutthroat trout ( Oncorhynchus clarki henshawi ) of variable sizes were examined. Higher constant temperatures (i.e., 24 °C) and more variable daily temperatures (i.e., 12–24 °C daily cycle) negatively affected growth rates. As fish mass increased (from 0.24 to 15.52 g) the effects of different thermal regimes on mass growth became more pronounced. Following 14 days exposure to the thermal regimes, feeding rates of individual fish were assessed during acute exposure (40 min) to test temperatures of 12, 18, and 24 °C. Feeding rate was depressed during acute exposure to 24 °C, but was not significantly affected by the preceding thermal regime. Our results indicate that even brief daily exposure to higher temperatures (e.g., 24 °C) can have considerable sublethal effects on cutthroat trout, and that fish size should be considered when examining the effects of temperature.     

Growth-independent effects of a fluctuating thermal regime on the life-history traits of the Japanese medaka (Oryzias latipes)

Abstract –  Temperature fluctuation has been shown to affect somatic growth rates and metabolic functions of fish, but little is known about the effects of fluctuating temperatures on life-history traits. We examined these effects on female Japanese medaka ( Oryzias latipes ) reared from hatch to maturity at two mean temperatures (27 and 30 °C) with diel temperatures either held constant or allowed to fluctuate ±5 °C. Feeding regimes were manipulated to equilibrate medaka growth rates in all treatments. Age and length at maturity decreased as a result of thermal fluctuation, whereas there was no effect of temperature fluctuation on the proportion of fish attaining maturity or on the number of eggs produced by a mature female. We hypothesise that short-term high temperatures associated with temperature fluctuation decreases development time, whereas reduced energy conversion efficiency at higher temperatures does not allow for increased egg production.