Growth response of African catfish,Clarias gariepinus (B.), larvae and fingerlings fed protease‐incorporated diets

African catfish, Clarias gariepinus (B.), is one of the promising freshwater fish species in African aquaculture but the expansion of its farming needs more production of its larvae. The use of live food organisms at first feeding for larvae is still obligatory. That increases the cost of larvae production. Hence, the incorporating of exogenous enzymes especially protease in artificial microdiets may provide affordable alternatives for enhancing the larvae performance. The present study was carried out to evaluate the growth and survival of larvae or fingerlings of African catfish fed artificial diets incorporated with different protease levels. Four artificial diets were formulated and enriched with protease enzyme at levels of 0.0, 750, 1,000, and 1,250 unit/kg diet; after that diets were made into crumbles (100–200 µm diameter). After absorption of the yolk sac, diets were offered to fish larvae (3.6 ± 0.2 mg) in triplicates as a starter feed up to apparent satiation every two hours for 30 days. In another treatment, fish larvae were fed on newly hatched Artemia nauplii (2,500 Artemia/L) as a starter food. In another experiment, African catfish fingerlings (10.1 ± 1.6 g) were fed on the same diets up to satiation twice a day for 2 months. It was noticed that the dietary protease improved larval growth and survival but not as Artemia nauplii did where fish larvae fed on Artemia nauplii showed highest growth and survival followed by those fed a diet enriched with 1,250 unit/kg diet of protease. The mortality of larvae fed protease‐enriched diets as well as the control diet was occurred mostly at the first week reaching its maximum at the third week. The poor growth was observed with fish larvae fed the control diet. Meanwhile, catfish fingerlings fed protease‐enriched diets showed higher growth over those fed the control diet. The larvae survival (11.0%–41.7%) was enhanced by increasing protease levels and it was lower than that of fingerlings (95.6%–100.0%). Furthermore, protein retention and digestibility were significantly improved with protease supplementation over the control diet especially at a level of 1,000 unit/kg diet. As compared with the previous studies, live food should be used in larvae rearing for the first week after that a starter diet enriched with protease at levels of 1,250 unit/kg diet should be used. In case of fish fingerlings, the dry diets should be enriched with 1,100 unit/kg diet to improve diet digestibility and subsequently enhance their growth.     

Use of the rotifer, Brachionus calyciflorus Pallas, in freshwater ornamental fish larviculture

The Brachionus calyciflorus used in this study were produced by batchculture using Chlorella spp. as feed. Larviculture experiments in indoor10-l and 200-l tanks revealed that, compared with egg yolk, the rotifersused as starter food significantly improved the growth and survival of DwarfGourami larvae (Day 2–12). These beneficial effects also extended tothe subsequent Artemia feeding phase (Day 13–32), suggesting that thequality of starter food is crucial to later development. At metamorphosis,the overall survival rate of larvae fed on rotifers in indoor tanks(65.1–74.5%) was about four times of that obtained in extensiveculture in open ponds (17.5%). In Discus, larvae are dependent on thebody slime of their parent as a nutrient during the first two weeks ofexogenous feeding. Our observation demonstrated that Brown Discus larvaecould be raised in the absence of the parent fish by using rotifers asstarter food followed by Artemia nauplii. Their growth and survival ratewere comparable to those on parental feeding. The artificial feeding wouldeliminate the risk of larvae being eaten by the parent fish and shorten thebrooding interval of the spawners, thereby leading to higher yield of fry.This feeding protocol is less tedious and more practical for use incommercial farming of Discus than the existing strategies of smuggling thebatch of larvae to foster parents or feeding the larvae with egg food. Theuse of rotifers would enable freshwater larviculture to improve larvalperformance, increase yield, and facilitate breeding of new fish specieswith small larvae.     

Trypsin activity and physiological aspects in larval rearing of European sea bass (Dicentrarchus labrax) using live prey and compound diets

The aim of this study was to evaluate the potential of a compound diet as a live prey substitute for feeding European sea bass larvae ( Dicentrarchus labrax L.). The effect of a commercial diet (Nippai ML feed) and live prey ( Artemia nauplii) on tryptic enzyme activity, protein content, growth (standard length) and survival rates of sea bass larvae were tested during a 27-day rearing experiment. Sea bass larvae were divided into two groups. The live food group (control group) was fed exclusively on newly hatched Artemia nauplii (Inve AF grade), the test group was fed exclusively with the compound diet from day 15 onwards. As trypsin has been demonstrated to be a useful indicator for evaluating digestibility of food and the nutritional condition of fish larvae, individual tryptic enzyme activity was determined in both feeding groups. Larvae older than 14 days after hatching and fed on live food showed a significantly higher tryptic enzyme activity than larvae fed the compound diet. A similar relationship between tryptic activity and standard length in both test groups was detected only in small larvae (standard length < 7 mm). The usefulness of proteolytic enzyme activity measurements in larval fish research, as well as its use in aquaculture nutrition research, was confirmed. Protein content, increase in length and survival rates of the sea bass larvae were additionally determined in order to evaluate an influence on the diet. The protein content of larvae fed the Artemia nauplii was higher and the growth of larvae fed the compound diet was reduced. Larval mortality was not affected by the diet given.     

不同开口饵料对西伯利亚鲟仔鱼生长、存活和体成分的影响

分别采用水丝蚓（Limnodrilus sp.）、卤虫无节幼体（Artemia nauplii）、枝角类（Moina sp.）和人工饲料饲养西伯利亚鲟仔鱼30 d,研究不同开口饵料对西伯利亚鲟仔鱼生长、存活率和体成分的影响.结果表明：卤虫无节幼体为西伯利亚鲟最适开口饵料,仔鱼的存活率最高（96.67%）; 投喂水丝蚓组生长速度最快;而人工饲料组生长速度明显低于其他组,且成活率最低.不同开口饵料组间仔鱼体成分差异显著,人工饲料组水分含量最高,且粗蛋白和粗灰分含量最低.采用卤虫无节幼体为西伯利亚鲟仔鱼开口饵料,然后采用水丝蚓进行强化培育,能获得较好的生长速度和存活率.     

Live food mediated vitamin C transfer to Dicentrarchus labrax and Clarias gariepinus

Live food enrichment techniques, using formulated diets and emulsions for improving the nutritional quality of Brachionus and Artemia , were studied as a tool for transferring ascorbic acid (AA) to fish larvae.
Artemia nauplii enriched for 24 h with an experimental emulsion containing 20% HUFA and 0%, 10% and 20% ascorbyl palmitate (AP) were administered to catfish larvae in a 20-day feeding trial. Survival was not affected by the dietary AA, but from day 7 onwards a significantly positive effect of supplemental AA on growth was demonstrated. At the end of the experiment the 20% AP group weighed 30% more than the control (0% AP), i.e. 9.5 and 6.3 mg DW, respectively. Evaluation of the physiological condition was demonstrated by salinity tests. In all three treatments larval growth was relatively low, and it still has to be verified if extra vitamin C in the diet really promotes growth. Seabass larvae fed on AP-enriched rotifers (days 4–12) and Artemia nauplii (days 13–46) showed no significant differences in production characteristics nor in stress resistance, however, for all salinity stress tests the 20% AP group performed better. AA was well incorporated into the predator larvae from the Brachionus feeding onwards.     

Experiments for the improved use of decapsulated Artemia cysts in intensive culture of African catfish larvae

Feeding dried and vitamin C enriched decapsulated Artemia cysts to African catfish larvae increased their growth rate significantly after 6 days over those fed only freshly decapulated cysts. Groups fed with Artemia nauplii had a significantly higher growth during the experiment, although this difference was not considerably important in practice. Tank colour had no influence on growth. Because of their lower price, the decapsulation of lower quality cysts can be an appropriate feed source in intensive cultures of African catfish larvae.     

Growth of Perca fluviatilis larvae fed with Artemia spp. nauplii and the effects of initial starvation

Experiments were performed to test the growth and survival of perch larvae fed with Artemia spp. nauplii and to determine the most advantageous time of first feeding. During a first experiment, perch larvae were divided into groups according to their hatching dates. Daily ingestion of Artemia spp. nauplii began significantly 2 days after mass larvae hatching. By day 7, the daily prey acceptance was over 75% among the separate larvae groups. During a second 14-day feeding experiment, larvae fed after a 2- or a 3-day delay showed the best growths: 12.5 mm and 13.7 mg. There was no significant difference (P > 0.05) among survival rates (85.3%) of perch larvae fed after a 1-, 2- or 3-day delay.     

The use of live and frozen Artemia salina nauplii enriched with fluorochromes for mass‐marking vendace Coregonus albula (L.) larvae

The aim of this study was to investigate the use of Artemia salina nauplii enriched with chosen fluorochromes for mass marking vendace Coregonus albula (L.) larvae. In the experiment, vendace larvae (6 DPH) were fed with live or frozen A. salina nauplii immersed in tetracycline hydrochloride (TC), calcein (Cal) or alizarin red S (ARS) for four subsequent days. More successful effects (marking otoliths) were obtained by feeding the fish with live nauplii enriched with fluorochromes, regardless of the dye type. The highest percentage of marked otoliths (100%) was recorded in the group fed with live nauplii immersed in TC. In the groups fed live or frozen nauplii enriched with Cal and ARS, a lower percentage of marked individuals (63.3%–73.7% and 56.7%–63.3%, respectively) were recorded. The survival rate of vendace larvae in particular groups oscillated between 93.7% and 95.7%. There were no significant differences in the total body length and body weight of the reared vendace larvae among different groups. In conclusion, for mass marking of vendace larvae using a feeding method, fish fed A. salinalive nauplii enriched with TC at a dose of 600 ppm is recommended for fishery practice.     

不同饵料对稀有鲫生长和繁殖的影响

饵料对鱼类生长发育和繁殖具有重要影响。为了筛选稀有鲫(Gobiocypris rarus)幼鱼和成鱼阶段最适投喂方式, 实验将出膜5周末(日龄为35 day after hatching)的幼鱼随机分为5个组: A组投喂丰年虫; B组每周前6d (days)投喂丰年虫, 后1d投喂商业化微颗粒S3饲料; C组每周前3.5d投喂丰年虫, 后3.5d投喂饲料; D组每周前1d投喂丰年虫, 后6d投喂饲料; E组一直投喂饲料; 各组均采用饱食投喂策略。每2周统计生长、存活指标, 直至第21周(147 dah), 在17周(119 dah)取材用于观察性腺发育程度。在产卵后统计各组产卵量、孵化率和子代畸形率。结果显示: (1)E组存活率和特定生长率显著低于其他组(P<0.05); (2)从产卵量、孵化率和子代畸形率上看, B组产卵量显著高于其他组(P<0.05); (3)从性腺组织学上看, 不同投喂方法对精巢的成熟度无显著影响, 但投喂过丰年虫的稀有鲫卵巢发育成熟度显著优于E组。研究结果提示:适量加入丰年虫比单一投喂活饵或饲料更有利于稀有鲫的生长和繁殖。建议在标准化养殖过程中, 幼鱼和成鱼期的稀有鲫采取丰年虫与饲料投喂频次比值为6﹕1的方式最佳。     

Development of larval diets for milkfish (Chanos chanos)

This study aimed to develop nutritionally balanced and cost-effective processed diets for milkfish larvae ( Chanos chanos Forsskal). Two larval diets (feed A and feed B) were formulated and prepared to contain 45&percnt| protein and 10&percnt| lipid. Several larval diet preparations were tried such as microbound/ unpelleted (freeze-dried), microbound/pelleted (oven-dried) and microbound/flaked (drum-dried) and assessed in terms of feed particle size and buoyancy, water stability and feed acceptability. The preparation that gave the best particle size and buoyancy as well as good water stability was prepared as the microbound diet (using K -carrageenan as a binder) and flaked using a drum drier. A series of feeding experiments were conducted to determine the growth and survival of milkfish larvae reared on various feeding schemes using these processed larval diets which were fed either solely or in combination with live feed. Larvae in control treatments were reared on live foods such as Brachionus plicatilis and Artemia nauplii. Larvae were observed to ingest the diets, indicating that the feeds had suitable physical characteristics and were attractive to the larvae. The overall results of the feeding trials showed that the artificial diets could be fed to milkfish larvae in combination with Brachionus rotifers starting on day 2 or day 8, and could be fed alone starting from day 15. These promising results would reduce the dependence of milkfish larvae on live feed and would have significant economic benefits in the form of simplified milkfish hatchery procedures.     

Food selection and growth of young snakehead Channa striatus

Food selection and growth of young snakehead Channa striatus were studied in the laboratory and in a field trial. In the laboratory, first-feeding snakehead larvae of 6–7 mm total length (TL) with a mouth opening of 0.55 mm selected for Artemia nauplii, and against formulated feed. Fish began feeding on formulated feed at 12mm TL when their mouth width reached 1.0mm. In both laboratory and field trials, snakehead diets changed as fish size increased. For fish 15–20 mm TL, cladocerans and copepods were 96.5% of their diet. With fish 30–40 mm TL, zooplankton consumption was greatly reduced while benthic organism consumption increased. Fish 45–50 mm TL fed exclusively on benthic invertebrates. Diet shift from zoo-plankton to benthic invertebrates was not due to reduced zoo-plankton availability, but was instead related to changes in gill raker structure. Low density of benthic invertebrates in the field trial caused reduced fish growth rates when fish switched diets from zooplankton to benthos. Our results indicate that snake-head can take Artemia nauplii as a larval starter food, then accept formulated feed at ≥12 mm TL. Zooplankton can serve as food for snakehead < 40 mm, but formulated feed should be provided for larger fish which are unable to catch zoo-plankton.     

Response of bighead carp Aristichthys nobilis and Asian catfish Clarias macrocephalus larvae to free-living nematode Panagrellus redivivus as alternative feed

The use of Panagrellus redivivus as live feed for bighead carp and Asian catfish larvae was tested. In experiment 1, carp larvae were given Artemia nauplii (control) or Panagrellus twice daily for 21 days. A third treatment consisted of unfed larvae. The same three treatments were used in experiment 2 plus another with a commercial entomopathogenic nematode (EPN). Bighead carp larvae given Panagrellus in experiment 1 had much lower growth and survival than those fed Artemia nauplii. This could be due to low nematode density (5–30 mL^?1 water) during feeding. The unfed larvae had 100% mortality by days 11–13. In experiment 2, growth and survival of carp larvae given Artemia nauplii (5–10 mL^?1) and Panagrellus (50 mL^?1) did not differ significantly (P > 0.05). All unfed larvae had died by day 13, while larvae fed EPN were all dead by day 8. Two experiments on Asian catfish were likewise conducted. In experiment 1, the catfish larvae were fed Tubifex (ad libitum), Panagrellus (50–100 mL^?1 per feeding) orArtemia (5 nauplii mL^?1 per feeding) three times daily for 14 days. In experiment 2, larvae were fed Artemia alone (10 nauplii mL^?1 per feeding), Panagrellus alone (100 mL^?1 per feeding), or their combination with a 38% protein dry diet twice daily. For both experiments, catfish larvae fed Panagrellus had significantly lower growth and survival than those fed Tubifex or Artemia. The combination of Panagrellus and dry diet created little improvement in the growth and survival of catfish larvae.     

Ammonia toxicity as a criterion for the evaluation of larval quality in the prawn Macrobrachium rosenbergii

The feasibility of a short-term ammonia toxicity test as an evaluation criterion for larval quality was assessed in three trials. In each one, Macrobrachium rosenbergii larvae originating from the same spawn were nutritionally differentiated in two groups by feeding them either a nutrient-rich (Artemia nauplii enriched for 24 h with n-3 highly unsaturated fatty acids (HUFA) and ascorbic acid (AA)) or a nutrient-poor diet (Artemia nauplii starved for 24 h). Throughout their development, larvae from both treatments were exposed during 24 h to six concentrations of total ammonia (NH₄⁺+NH₃) and a control (no ammonia added). Based on mortality rates, the median lethal concentration for 50% of the population (LC₅₀) was estimated. As expected from earlier work, larvae fed the optimal diet presented higher n-3 HUFA and AA contents as well as higher growth and metamorphosis rates. From the moment the effect of diet quality was analytically detectable in the tissues of the larvae, the ammonia test was able to distinguish both groups of larvae. Differences in ammonia tolerance were observed as early as larval stage 4 and remained evident throughout larval development. The short-term ammonia toxicity test proved to be a valuable, sensitive and reproducible criterion for the establishment of larval quality.     

Evaluation of the probiotics Bacillus subtilis and Lactobacillus plantarum bioencapsulated in Artemia nauplii against vibriosis in European sea bass larvae (Dicentrarchus labrax, L.)

Two potential probiotics Bacillus subtilis and Lactobacillus plantarum were evaluated for use in aquaculture as preventive measures against vibriosis. In vitro evaluation of the probiotics using co-culture assays with the pathogen Vibrio anguillarum and testing for the production of antibacterial substances showed the presence of antagonism and confirmed the production of antibacterial substances. Both potential probiotics were administered to the live fish feed Artemia franciscana nauplii, offering protection against a subsequent challenge of the nauplii with the fish pathogen V. anguillarum, with best survival rates of the nauplii and the most efficient protection offered by B. subtilis. Nauplii enriched with B. subtilis were further used to evaluate the protection of sea bass larvae against vibriosis. The untreated group of fish challenged with V. anguillarum presented low survival of 36.7 %, while the fish treated with nauplii enriched with the probiotic B. subtilis showed significantly increased survival rates of 86.7 % after challenge with the pathogen. The survival of healthy unchallenged fish treated with the probiotic was not significantly different from control unchallenged fish (90-94 %). Our results indicate that B. subtilis is a probiotic suitable to be used for the prevention of vibriosis in fish larvae and can be safely administered through their live feed Artemia nauplii.     

Effects of experience on feeding success by larval white seabass, Atractoscion nobilis

Laboratory experiments on larval white seabass, Atractoscion nobilis , showed that first feeding success on mixed zooplankton was zero, and less than 5% on Artemia nauplii , for larvae of different sizes. Experience increased success from 20% after 2 days to 69% after 14 days when larvae fed on Artemia nauplii , and to 42% after 4 days of feeding on zooplankton. This increase was attributed to learning in larvae less than 5·0 mm s.l. , and in part to size-related factors in larvae greater than 5·0 mm s.l.     

Critical involvement of dietary docosahexaenoic acid in the ontogeny of schooling behaviour in the yellowtail

To investigate involvement of the central nervous system in the ontogeny of behaviour, diets of differing quality were used to rear yellowtail Seriola quinqueradiata larvae and juveniles. Artemia nauplii enriched with oleic acid (OA), eicosapentaenoic acid (EPA), or two different concentration levels of docosahexaenoic acid (DHA) were fed to yellowtail larvae (L^T 7 mm; 13 days old) for 12 days, and their behavioural development was analysed together with growth, survival, activity and fatty acid composition. Yellowtail fed with DHA–enriched Artemia showed mutual attraction behaviour at 11 mm L^T, while those fed with OA– or EPA–enriched Artemia did not show this behaviour at the same size. While fish in the OA group showed poor growth, survival and activity index, fish in the EPA group were similar to the two DHA groups. In addition, most fish tested, including the OA group, showed clear optokinetic responses. Fatty acid composition of the diet was reflected in that of the fish body. Therefore, dietary DHA in the larval stage is considered to be essential for the development of schooling behaviour in the yellowtail.     

Effects of two Avtemia diets with different contents of polyunsaturated fatty acids on the lipid composition of larvae of Atlantic herring (Clupea harengus

Atlantic herring larvae ( Clupea harengus ) were fed two enriched Artemia diets with different contents of (n-3) highly unsaturated fatty acids (HUFA), one containing low levels of 20: 5(n-3) and no 22: 6(n-3), the other containing substantial levels of both 20: 5(n-3) and 22: 6(n-3). After 30 days of culture, fatty acid compositions of lipid classes in the heads, bodies and eyes of the larvae were analysed. Fish fed Artemia with the low (n-3) HUFA diet lacking 22: 6(n-3) had lower amounts of total (n-3)HUFA and, in particular, of 22:6(n-3) in individual phospholipids and total neutral lipids of heads, bodies and eyes as compared to fish fed Artemia with high levels of (n-3)HUFA. The amount of 22: 6(n-3) in the fatty acids of phosphatidyl-ethanolamine of eyes was particularly susceptible to dietary depletion. The implications of these findings are discussed, particularly in relation to dietary requirements for 22: 6(n-3) during development of neural tissue in predatory fish iarvae.     

4种生态因子对虎斑乌贼幼体生长与存活的影响

旨在研究温度、盐度、饵料种类、投饵量对虎斑乌贼（Sepia pharaonis）幼体生长与存活率的影响,以确定其生长发育的最佳生态条件,为人工育苗提供理论依据。在室内控制条件下,采用单因子试验研究了不同温度（18、21、24、27、30和33℃）、不同盐度（18、21、24、27、30和33）、不同饵料种类（虾糜、活糠虾、卤虫无节幼体、桡足类、死糠虾、虾糜＋强化卤虫后无节幼体、强化卤虫后无节幼体）、活糠虾不同投饵量（0、2、4、6、8和10 g/d）对虎斑乌贼幼体生长发育的影响。结果显示：不同温度对虎斑乌贼幼体生长影响显著（P〈0.05）,最适温度为24-27℃,在最适温度下,存活率为84.4%-91.1%,特定生长率为4.82%-6.13%,存活率（y）与温度（x）的函数关系为y=-0.15x3＋30.637x-447.002（r2=0.923）。幼体适宜盐度为24-33,最适盐度为27,在最适盐度条件下,其存活率为（90.0±5.29）%,特定生长率为（3.71±0.34）%。投喂7种开口饵料,以活糠虾效果最佳,存活率为（96.7±2.94）%,特定生长率为（3.77±0.23）%;强化卤虫后无节幼体效果次之,存活率为（95.6±2.31）%,特定生长率为（2.54±0.15）%,其余各组培养效果均不理想。投喂活糠虾,随着投饵量的增加,其存活率随之提高,摄食量（y）与个体重（x）的回归方程为y=0.227x-0.063（r2=0.921）。     

Allometric growth and functional development of the gut in developing cod Gadus morhua L. larvae

The development of the gut epithelium in cod Gadus morhua was studied during the larval period in intensive rearing systems. Cod larvae were fed enriched rotifers from mouth opening. On 17 days post‐hatch (dph) one group of larvae were fed Artemia sp. nauplii while another group were fed both rotifers and a formulated diet (co‐fed). At the end of the experiment (30 dph) larvae receiving live feed were almost three times larger than the co‐fed larvae, although no clear signs of pathological effects due to feeding regime were found in any larvae sampled for morphological studies. The midgut volume in larvae fed live feed increased by a factor of 38 during the experiment, and in particular volume increased rapidly between 24 and 30 dph. The enterocyte size increased between 12 and 24 dph from 652 ± 64 to 1479 ± 144 μm³ (mean ±s .e .). When enterocytes reached their maximum size, several morphological changes in the gut epithelium were initiated, such as increased number of mitochondria per enterocyte, increased size of the nuclei and a considerable increase in microvilli surface area. The mitochondrial membrane structures changed during the experiment, suggesting a maturation process of the mitochondria. The midgut development was strongly related to larval size rather than age. On 30 dph co‐fed larvae were equal in size to Artemia sp. fed larvae on 24 dph. This was reflected by equal values of estimated midgut volume, midgut length and total number of enterocytes and the number of mitochondria per enterocyte. The microvilli surface area, however, was significantly larger in co‐fed larvae on 24 dph compared to live‐feed larvae on 30 dph. This increase in absorptive surface was probably a response to suboptimal feeding conditions. The strong correlation between gut development and larval size and the lack of clear pathological effects, suggested that the gut tissue is flexible and can withstand periods of suboptimal nutrition at this stage.     

Sibling cannibalism in dorada under experimental conditions.

Cannibalism among embryos and larvae of Brycon moorei (Characidae) occurs during daytime and night-time, and persists under permanent darkness. Embryos and larvae of dorada provisioned with formulated feed over the first week of exogenous feeding did not survive, except for those exerting cannibalism. When oered alternative fish prey [embryos of Prochilodus magdalenae (0·5–0·8 mg) and Oreochromis niloticus (9·10 mg)], 1-day-old embryos of dorada preferred preying on these, thereby reducing early cannibalism. However, this promoted depensatory growth and more intense cannibalism later in the larval stage. Dorada provisioned with Artemia nauplii in excess showed more homogeneous growth and higher survival, most cannibalistic acts being restricted to the first 24 h of exogenous feeding, just after oral teeth were fully developed (21 h after hatching). Provisioning dorada with Artemia nauplii a few hours before their oral teeth were fully developed reduced early cannibalism from 41 to 15%. High proportions of deformed fish caused higher mortality, both directly and indirectly, as they promoted early cannibalism, depensatory growth and more intense cannibalism among larvae. The initial sorting of embryos, based on their occupation of the water column improved survival significantly during the first week of exogenous feeding, up to 52% in progenies containing <10% of deformed fish. Size-grading of larvae and young juveniles over the next 2 weeks reduced cannibalism to 2·6 and 1·9% day ⁻¹, in the first and second weeks, respectively. These results indicate that cannibalism in dorada can be mitigated eciently through appropriate rearing procedures, and open promising perspectives for the intensive culture of this fast-growing tropical species.