Improvement in the feeding efficiency of larval,post larval and juvenile Dover sole (Solea solea L.) by the use of staining to improve the visibility of Artemia used as food

The feeding efficiency of larval, post larval and juvenile Dover sole (Solea solea L.) was studied by using Artemia stained with five different food colourings — brilliant blue, pink, lemon yellow, red “C” and black.The results show that the feeding efficiency is markedly improved by this treatment. The maximum feeding efficiency was found using black stained Artemia and minimum for the unstained control. This clearly suggests that the contrast perception of the food in relation to the illumination of the background is of major importance especially during the critical weaning period of the larval stage when feeding is being established.     

Experiments of the rearing of larval turbot, Scophthalmus maximus L.

Experiments on the live food requirements of cultured turbot larvae are described. A mixture of six species of unicellular algae did not sustain early larvae, but the growth and survival of larvae fed with rotifers were considerably improved when the rotifers were feeding on Isochrysis galbana rather than on Dunaliella tertiolecta. Oyster (Crassostrea gigas) larvae offered alone or with rotifers, did not produce higher larval growth or survival than rotifers alone. Black tanks were found to be more suitable than white tanks for rearing larval turbot.     

Predation and energetics of Penaeus indicus (Decapoda: Penaeidae) larvae feeding on Brachionus plicatilis and Artemia nauplii

Brachionus plicatilis and Artemia nauplii were fed to a number of larval stages of the penaeid prawn Penaeus indicus to determine ingestion rates, larval energy requirements and to establish at which stage larval predation commenced. The raptorial feeding rates were then contrasted on an energy basis with filter feeding rates for P. indicus larvae to compare the relative efficiency of these two feeding mechanisms. Brachionus was first eaten as early as protozoea 1 to protozoea 2, while the maximum ingestion rate of 300 rotifers larva^?1 d^?1 (1.06 J larva^?1 d^?1) was obtained during protozoea 3 to mysis 1. Artemia were effectively ingested by P. indicus protozoea 3 (4.1 J larva^?1 d^?1) to post-larva (8.2 J larva^?1 d^?1). Daily energy intake rate from filter feeding increased from 1.1 J larva^?1 d^?1 during protozoea 1 to reach a peak of 5.32 J larva^?1 d^?1 during mysis 3 after which it declined to 2.66 J larva^?1 d^?1 during the post-larval stage. This decline in energy intake from filter feeding with a concomitant increase in energy intake from Artemia predation demonstrates a predominant feeding mode changeover point during mysis 3. Energy intake was consistently low with Brachionus, indicating that it may be unnecessary for commercial culture purposes.     

Egg incubation and larval rearing of navaga (Eleginus navaga Pall.), polar cod (Boreogadus saida lepechin) and arctic flounder (Liopsetta glacialis Pall.) in the laboratory

The embryonic and larval development of three White Sea cold-water fish species, rate of yolk sac absorption, age at first feeding and their survival and growth when fed different food organisms, were studied.Eggs were obtained from spawners in the Bay of Kandalaksha, White Sea, and incubated in troughs and aquaria at a mean temperature of 1.5 °C, slightly above that of the sea. The incubation period for polar cod eggs lasted 35 days, for arctic flounder, 42 days and for navaga eggs, 48 days. Emergent larvae were 5.5–6.0 mm long and began feeding at 2–4 °C, 5–6 days (navaga) and 12–14 days (polar cod) after hatching, when their yolk sac was still fairly large.They were fed day-old Artemia nauplii and zooplankton taken from the sea and consisting of Calanus and Pseudocalanus nauplii 400–600 μ in length.The period of establishing first feeding is the most critical for larvae.     

Mariculture potential of the spot prawn, Pandalus platyceros Brandt

Biological characteristics and culture methods were investigated for the spot prawn, Pandalus platyceros Brandt. Ovigerous adults were caught in the local fishery; six of these produced 2 628 to 4 669 larvae. The larval period ranged from 26 to 35 days (9.5–12.0°C). Maximum larval survival was about 70%, with mortalities being most frequent during ecdysis. The relation of wet weight (g) to carapace length (mm) for the first 26 months was calculated as log W = ?3.0843 + 2.9308 log L. Prawns showed good survival between 9.5 and 21.0°C. Mortality increased sharply when temperatures exceeded 21.0°C. Salinities below 22‰ resulted in a sharp increase in mortality.A diet of brine shrimp nauplii sufficed for newly hatched larvae. Growth was enhanced when larvae were fed a unicellular algal supplement (Phaeodactylum tricornutum), although mortality was somewhat higher. Larvae progressed rapidly to foraging on larger brine shrimp and diced foods. Six-month-old spot prawns raised on a squid diet averaged 3.4 g, and at 1 year the mean weight was 6.3 g. A feeding experiment, incorporating 12 diets, disclosed that highest growth rates and best food conversion ratios were achieved on a combined California seamussel and giant red sea urchin diet. However, the best growth rate achieved was considered marginal for mariculture.It was concluded that unless the growth rate could be accelerated by other food formulations or culture techniques, a monoculture system for mass cultivation would not be feasible. The spot prawn may have potential in a polyculture system.     

Elevage larvaire d'Artemia salina (Branchiopode) sur nourriture inerte: Spirulina maxima (Cyanophycee)

A technique for the intensive rearing of Artemia salina larvae (Branchiopoda) of 1 – 4 mm using the blue-green algae, Spirulina maxima (Cyanophycea) in dry powder form is described. Experimentation was carried out in a small volume (20 l) and techniques were simplified whenever possible to enable minimal handling (i.e. water is not renewed). The system is therefore easily applicable to medium and large volumes. The production requirements of Artemia salina for larval aquaculture at Centre Océanologique de Bretagne have been fulfilled by this technique since 1974 in 450-l volumes. Growth and survival rates have been satisfactory to date.Up to a certain threshold and within a given age group, the amount of food introduced influences mean population size. Under optimal conditions it is possible to rear larvae of 1 mm in 2 days, 2 mm in 4 days and 3.75 mm in 6 days. The minimal food supplies required to obtain these figures are respectively 600 mg, 1 800 mg and 4 300 mg of Spirulina powder for 10 000 larvae at the ages of 2, 4 and 6 days. These rapid growth rates are achieved by overfeeding the larvae, which results in a reduction in the size of the installations and in time demanded for culture maintenance. The use of an optimal feeding regime gives a growth rate very close to the maximum and diminishes production costs only slightly.Consequently, an optimal larval concentration per unit volume is the most economically feasible choice for a production unit. The maximum larval concentration which gave good growth and survival rates was established for an average food quantity (3 200 mg/10 000 larvae). Larval densities may reach 13 to 14 2-day-old larvae (1 mm), five 4-day-old larvae (2 mm) and two 6-day-old larvae (3.75 mm) per ml of water. To regulate the concentration of Artemia, fixed volumes of the culture are removed regularly, thus considerably increasing the production of a given tank. The weekly production of a 450-l tank is approximately 75 g of dry matter.     

海洋尖尾藻对2种海洋微藻的摄食特征研究

为研究海洋尖尾藻对双色藻和齿状纹石藻的摄食特征,分别采用2种海洋微藻为饵料培养海洋尖尾藻,分析海洋尖尾藻对2种海洋微藻的摄食过程、培养液颜色变化特征和摄食规律。结果显示,海洋尖尾藻摄食双色藻时将藻丝一段一段慢慢裹入纵沟,而齿状纹石藻整个细胞同时被裹入纵沟。海洋尖尾藻接种6 h后,对2种海洋微藻的摄食率均为100%。随着海洋尖尾藻细胞初始密度(双色藻培养液中分别为0.8×104、2.4×103和0.8×103个/mL,齿状纹石藻培养液中分别为3.9×103、2.4×103和1.7×103个/mL)降低,其种群在初始密度为3.4×107个/mL的双色藻培养液中达到稳定期所需时间增加,分别为接种后第3、4和6天,双色藻被摄食完毕所需时间也增加,分别为接种后第5、10和15天;海洋尖尾藻种群在初始密度为6.6×105个/mL的齿状纹石藻培养液中达到稳定期所需时间增加,分别为接种后第4、5和12天,齿状纹石藻被摄食完毕所需时间也增加,分别为接种后第6、7和13天。研究表明,海洋尖尾藻对不同大小和体制类型的双色藻和齿状纹石藻的摄食过程不同,培养方式对培养液颜色变化产生影响,饵料藻种类以及饵料藻和海洋尖尾藻最初浓度配比会影响海洋尖尾藻摄食,15 d培养过程中双色藻种群和齿状纹石藻种群均向海洋尖尾藻种群发生了演替。     

The culture of the diatom Chaetoceros gracilis and its use as a food for penaeid protozoeal larvae

The use of the solitary diatom Chaetoceros gracilis as the exclusive food for Penaeus stylirostris and P. vannamei protozoeal larvae produced high survival rates in 40 m³ tanks at a commercial shrimp hatchery. The diatom was maintained in the laboratory at 25–26°C and grew vigorously in the hatchery tanks at 28–30°C.Simple and inexpensive procedures for maintaining stock cultures of C. gracilis and for growth of cultures in the laboratory and hatchery were developed. A problem encountered in the hatchery tanks was the occasional development of a high-density bloom followed by its collapse. This resulted in mass larval mortality. Techniques to maintain the diatoms within desirable concentrations, and to prevent larval mortality if diatom concentrations fell short of or exceeded these limits, are described.     

Early development of the shortfin silverside Chirostoma humboldtianum (Valenciennes, 1835) (Atheriniformes: Atherinopsidae)

The shortfin silverside Chirostoma humboldtianum has been considered for culture in Mexico, but success has been limited by a poor knowledge of its early development. First synthesis of the early development of the shortfin silverside is presented to determine conditions suitable for rearing. Brooder maturation was induced through photothermal cycles. C. humboldtianum ova were fertilized in vitro. The eggs were incubated in reconstituted water (160-180 mg/L CaCO₃) at 18 °C and 5 gm of NaCl per litre. During the hatching day, 300 shortfin silversides were stocked and followed up until metamorphosis in order to establish the timing of exogenous feeding, changes in food type, growth and development during critical periods for survival, according to the theory of saltatory ontogeny. Free embryos hatched 12 days after fertilization at 18 °C. First critical point for survival is the beginning of exogenous feeding. Free embryos started mixed feeding on day four of post-hatching (dph), point of no-return was presented towards the end of mixed feeding on 6 dph, larval period began at six (dph) when the anus is opened, and metamorphosis to juvenile was presented at 65 dph with a SL of 19.34 ± 2.28 mm, when scales and fins were well developed. Differences in growth between periods were detected: free embryos growth slower than larvae but mouth size depicted a larger growth rate in the former. Cephalic length and mouth size were negatively related to standard length in embryos and larvae. Mouth size was positively related to cephalic length in free embryos but negative in larvae. Results suggest that during the free embryo phase, growth priorities are directed to the development of apparatuses and systems; whereas, during the larval period, energy is directed to growth in length, mouth size and development of fins, which allows them to increase their swimming velocity, grants them a greater capacity to obtain exogenous food and, in consequence, increases fitness for survival.     

Optimisation of Artemia feeding rate for carp larvae (Cyprinus carpio L.)

Carp (Cyprinus carpio) larvae were fed on measured numbers of Artemia nauplii, and daily growth of the larvae monitored for a period of 10 days in order to determine the effect of varying feeding levels. A 34% reduction in specific growth rate was observed over the experimental period. At a temperature of 24 ± 0.5° C, carp larvae were found to require 200–250% of their body weight of Artemia nauplii per day for optimal growth and food conversion during the first five days of feeding, reducing to 100–120%/day over the following five days. The significance of these results is discussed in relation to potential economies of Artemia cyst use in hatcheries.     

The food value of Phaeodactylum tricornutum Bohlin to the larvae of Ostrea edulis L. and Crassostrea gigas Thunberg

The food value of three cultures of Phaeodactylum tricornutum composed of three different cell forms was measured for the larvae of the bivalve molluscs Ostrea edulis and Crassostrea gigas. While all three types supported good growth of both species of larvae, there were no significant differences in food value between the three and the Isochrysis galbana controls. Increasing the feeding rate of one type of P. tricornutum culture had no marked effect on the growth rates, survival or settlement of C. gigas larvae in the range equivalent in terms of dry weight to 25–200 cells I. galbana/μl.     

淀山湖光泽黄颡鱼食性研究

于2009年8月至2010年7月在上海市淀山湖采集光泽黄颡鱼胃含物样品,采用传统镜检法对其食性进行研究。结果表明:淀山湖光泽黄颡鱼全年均有摄食,且摄食强度存在显著的季节变化,其中饱满指数排序:秋 > 春 > 冬 > 夏,春季空腹率显著高于其他季节;共鉴定其饵料生物7大类(11小类),聚类分析表明,出现率(F%)、数量百分比(N%)和相对重要性指数(IRI%)在衡量食物对光泽黄颡鱼的重要性方面表现一致,重量百分比(W%)与前三者存在显著差异,综合以上4种指数显示,底栖甲壳类、多毛类和水生昆虫是光泽黄颡鱼的主要食物来源;选用W%对其食性进行时空比较,聚类分析显示其冬季食物组成与其他季节存在显著差异,而站点间差异不明显,均以底栖甲壳类为绝对食物来源;食物组成Shannon-Weiner多样性存在明显的空间差异,高低依次为S5 > S3 > S4 > S2 > S1 > S6,研究认为光泽黄颡鱼食性具有较强的地域性和可塑性。     

Growth rate and conversion efficiency of the air-breathing catfish, Heteropneustes fossilis, in relation to ration size

Effects of different feeding rates (0–20% live body weight) on food intake, growth and conversion efficiency of Heteropneustes fossilis were studied using the oligochaete worm Tubifex tubifex as food. An amount of worm substance equivalent to 12.73% live body weight/fish day^?1 represents the maximum amount which a 4.015 ± 0.340-g H. fossilis can consume under laboratory conditions. Geometrically derived feeding rations of 12, 40 and 130 mg/g live fish day^?1 represent the maintenance, optimum and maximum levels for H. fossilis. The SDA (specific dynamic action) increased from 14 mg/g day^?1 at optimum to 70 mg/g day^?1 at maximum feeding rate.     

Productivity improvement of Lysmata seticaudata (Risso, 1816) larval rearing protocol through modelling

The Monaco shrimp Lysmata seticaudata (Risso, 1816) is a marine ornamental species whose ecology and biology, as well as its larval culture has previously been addressed. The objective of the study was to predict and improve productivity of this species rearing protocol through modelling. The models developed intend to help aquaculturists to maximize survival to postlarva, decrease larval duration and increase synchronism of metamorphosis and newly metamorphosed postlarvae size by manipulating temperature, diet, first feeding period and stocking density.The models developed allow us to conclude that the L. seticaudata rearing protocol productivity can be improved by raising larvae at a density of 40 larvae L^− 1 and fed newly hatched Artemia nauplii since hatching to zoea V, and with Algamac 2000™ enriched Artemia metanauplii from zoea V to metamorphosis to postlarvae.By providing more productive protocols to aquaculturists, destructive practices and wild collection may be reduced.     

抑食金球藻对卤虫和鼠的急性毒性及对兔皮肤和眼的刺激作用

2011年夏季,我国秦皇岛沿岸海域再次暴发了大面积的微微型浮游植物抑食金球藻褐潮。为了弄清该藻的毒性以及评估其对人们生命健康的影响,本实验以卤虫作为受试生物,在室内条件下测试了该褐潮水体对卤虫的急性毒性及卤虫对该藻的摄食作用,并以室内纯种培养的抑食金球藻对小白兔进行急性皮肤刺激和眼刺激实验,对小白鼠进行急性经口毒性实验。结果表明,抑食金球藻褐潮水体对卤虫无急性毒性,卤虫能以抑食金球藻为食,摄食率随着摄食藻密度的升高而上升。抑食金球藻藻液对实验兔的皮肤和眼睛无明显刺激作用,对小白鼠无急性毒性作用。该藻暴发褐潮时,对人们的生命健康安全影响较小。     

Studies on the biology of young grey mullet, Mugil cephalus L. II. Food and Feeding

This is the second of a series of investigations into the biology of young grey mullet, Mugil cephalus L., and the feasibility of its culture in the coastal, estuarine waters of Sri Lanka. The food and feeding habits of mullet, 20–55 mm in length, from the coastal Negombo Lagoon (7° 10′ N; 79° 50′ E) were studied from November 1974 to October 1975.The feeding intensity, estimated as the number of food organisms found in stomachs per feeding individual, followed a seasonal pattern with the intensity increasing from April onward and reaching a peak during June–August. Over 80% of the individuals were found to feed throughout the year. The diet consisted of 18 genera of diatoms, eight genera of green algae, some desmids, six genera of blue-green algae and eight other food groups. No sand or detritus was found to occur in fish smaller than 25 mm in length, and the percentage occurrence of detritus and/or sand particles increased with increase in body length. Quantitatively and qualitatively, diatoms were the most predominant food items, accounting for more than 50% of the total diet. Although only one genus of Xanthophyceae was found to occur in the diet, its contribution was significant.M. cephalus was found to show diurnal periodicity in feeding activity; peaks of activity occurred at dawn and around midday and were unrelated to the state of the tide.The significance of the nature of the diet and the occurrence of two peaks of feeding activity within a 24-h period is evaluated in the light of present knowledge of the food and feeding behaviour of M. cephalus at various stages of growth, and the possibilities of polyculture with other herbivorous species is discussed briefly.     

Effect of an experimental microparticulate diet on the growth, survival and fatty acid profile of gilthead seabream (Sparus aurata L.) larvae

In recent years, a great deal of interest has emerged in the development of microdiets as an economic alternative to live food, in the larval culture of marine fish species. The ability to grow Sparus aurata larvae on a prototype microparticulate diet was examined. To achieve this objective, four feeding regimes differing in the time when the microdiet was introduced (3, 7 or 12 days) and one based exclusively on an inert diet were tested, during the first 22 days of larval life. Significant differences in larval growth were found between the experimental feeding regimes and their corresponding controls (enriched rotifers during the whole experimental period); the larvae in the co-feeding regimes and with an exclusive microparticulate diet were always significantly smaller than larvae fed on rotifers alone. However, the difference was minimised by introducing the inert diet at a later date. A lower survival was found in larvae with a co-feeding regime, in comparison with the control treatments and the survival was significantly lower in larvae fed exclusively on a microparticulate diet. The fatty acid analysis revealed that the experimental microencapsulated diet and the rotifers enriched with Protein Selco® presented relatively similar fatty acid content. In spite of the slightly higher (n?3)/(n?6) and Docosahexaenoic acid (DHA)/Eicosapentaenoic acid (EPA) ratios and somewhat lower highly unsaturated fatty acid (HUFA) content found in the inert diet, the fatty acid composition of the diets cannot explain the differences found in larval performance. The results revealed that the complete replacement of live prey with the tested microparticulate diet is still not possible in S. aurata larval rearing. Nevertheless, better growth and survival results and a substantial reduction in the daily supply of live food can be achieved with a combination of microdiet and live prey.     

The influence of stocking density and food ration on fry survival and growth in Oreochromis mossambicus and O. niloticus female × O. aureus male hybrids reared in a closed circulated system

First-feeding stage tilapia fry were reared for 40 or 50 days in 20-l capacity aquaria at six stocking densities (2, 4, 6, 8, 10, 12 l^?1) and three feeding levels (6, 12, 24% of body weight daily). Fry survival and growth were improved at the higher feeding levels, but the percentage of fry surviving showed no consistent relationship to stocking density. Cannibalism accounted for a mortality rate of 10–35% in each experimental group and was inversely related to the level of feeding. Under equivalent conditions, O. niloticus female × O. aureus male fry had a higher rate of survival, better food conversion and were more uniform in size than O. mossambicus fry.     

Ecological and Ethological Perspectives in Larval Fish Feeding

ABSTRACT

Low survival rates during larval stages constitute a major bottleneck in the successful culture of many marine and some freshwater fish. The availability of live food is recognized as a critical factor influencing larval survival. Live food is still superior to the best larval diets in terms of larval survival and growth. This paper reviews important ecological and ethological aspects of feeding, from hatching tothe weaning stage, and relates them to problems in larval culture. In general, freshwater fish larvae are easier to raise than marine fish larvae, because at hatching they are larger and endowed with more yolk reserves, are less sensitive to starvation, and canbe weaned to artificial diets sooner. The feeding behavior of the larvae can be analyzed in terms of the sequential components of predation: search, encounter, pursuit, attack, capture, and ingestion. The searching efficiency and encounter rates of the visual predator are influenced by prey parameters such as body size, conspicuousness, and evasiveness. Turbidity of the water and light intensity also affect prey detection. To changing prey densities, the larvae show typical Type II functional responses, which are influenced by prey handling time, which in turn is largely a function of prey size. Knowledge of larval functional responses is helpful in providing the right concentrations oflive food for larval culture. The larvae are initially gape-limited and exhibit prey size selectivity but gradually widen their prey size range as they grow. An aquacultural application of this is the commonly employed feeding protocol, prey size sequencing, in which progressively larger live food items are offered as the larvae grow. A thorough knowledge of the feeding behavior is also essential in the formulation of acceptable larval diets.     

Growth,survival and fatty acid composition of Rhamdia quelen (Quoy and Gaimard, 1824) larvae fed on artificial diet alone or in combination with Artemia nauplii

Black catfish (Rhamdia quelen) is a species of interest for aquaculture in Brazil, Argentina and Uruguay. A feeding trial was conducted to evaluate the effect of feeding R. quelen larvae on either only an artificial diet or in combination with Artemia nauplii (AN) on larval performance and fatty acid composition. For 12 days, larvae were fed from first feeding (3 days after hatching, TL = 5.88 ± 0.23 mm) with artificial food only or a combination of artificial food and AN (co‐feeding). At the end of the trial, total length of co‐fed larvae was significantly higher than that of larvae fed solely artificial food (P < 0.001). No significant differences were found in survival rates. Co‐feeding microdiet with a small amount of AN significantly affected larval fatty acid composition. Lipid and fatty acid composition of food and larvae revealed the importance of n‐3 fatty acids for growth of black catfish larvae and that, as most freshwater fish, R. quelen larvae can elongate and desaturate linolenic acid to n‐3 highly unsaturated fatty acids. Results suggest that R. quelen larvae can be fed from first feeding on microdiets as unique food source, although better larval performances are obtained by co‐feeding with a small amount of AN.