Effects of varying Artemia enrichment on growth and survival of juvenile seahorses, Hippocampus abdominalis

Seahorses are the focus of recent aquaculture ventures in a variety of countries. Many of these ventures utilise enriched live Artemia (to varying degrees) to feed their seahorses. Given the range of commercially available enrichment products that can be used to enrich Artemia, it is imperative to determine which of these may promote the best growth and survival in seahorses, as well as being most cost-effective. This investigation tested the effects on juvenile seahorse (Hippocampus abdominalis Leeson, 1827) growth and survival through enriching Artemia with three commercial enrichment products: Super Selco®, DHA Protein Selco® and Algamac-3050. These were tested against a low-cost Artemia on-growing mixture used in this instance as an enrichment (90% Eyre Peninsula Aquaculture brine shrimp food (EPABSF)/10% spirulina).

After 3 months, there was a significant difference in juvenile length between the enrichment treatments, with juveniles in the DHA Protein Selco® and Algamac-3050 treatment longer than juveniles in the Super Selco® treatment, but not longer than juveniles in the EPABSF/spirulina treatment. There was also a significant difference in juvenile wet weights between the treatments, with juveniles in the Super Selco® treatment weighing significantly less than juveniles in the other three treatments.

In terms of condition factor (CF), there was a slight significant difference between the treatments, with juveniles in the DHA Protein Selco® and EPABSF/spirulina treatment having higher CFs than juveniles in the Super Selco® treatment, but not the Algamac-3050 treatment. Mean daily specific growth rate (SGR) for Super Selco® was lower than the other three treatments. There was no effect of enrichment treatment on seahorse survival with 100% survival in all four treatments.

Fatty acid analysis revealed marked differences in the Artemia enriched with the various enrichment products. Super Selco®- and Algamac-3050-enriched Artemia had the highest percentage of docosahexanoic acid (DHA), 22:6(n−3), while Super Selco®-enriched Artemia had the highest percentage of eicosapentaenoic acid (EPA), 20:5(n−3). EPABSF/spirulina-enriched Artemia had the highest percentages of C18 fatty acids. Percentage of polyunsaturated fatty acids (PUFA) and n−3 PUFAs were highest in Super Selco®- and Algamac-3050-enriched Artemia. Proximate analysis revealed little difference among all four enrichment treatments in terms of protein, fat and carbohydrate levels.

The results from this experiment demonstrate that when culturing H. abdominalis, all three commercial enrichment products produce good seahorse growth and excellent survival. However, on a cost/benefit basis, all three commercial products were outperformed by the cheaper Artemia on-growing mixture (EPABSF/spirulina).     

Effect of Feed Type and Age-at-weaning on Growth and Survival of Clownfish Amphiprion percula (Pomacentridae)

To simplify the weaning of clownfish Amphiprion percula from live food to artificial food, and to reduce the costs of feeding live food, three trials were undertaken to determine the best age for weaning. Twenty-nine-day-old post-hatch A. percula were weaned onto a fishmeal/caesin-based dry food which was an acceptable substitute for either Artemia or a moist food comprising Penaeus indicus and Donax serra. Larvae weaned 4 days after hatch (DAH) had lower survival than fish weaned 7 or 10 DAH. In juveniles weaned from 10 to 30 DAH good survival was obtained between 15 and 20 DAH suggesting that this is a suitable window for the weaning of this species.     

A comparison of artificial and natural foods and their combinations in the rearing of goldfish, Carassius auratus (L.)

Intensive grow‐out of goldfish, Carassius auratus (L.), larvae and juveniles in closed systems requires the control of environmental conditions and feeding. This study investigates the use of different types of live food and combinations of live food and dry food in a series of four rearing experiments. Juvenile goldfish can be weaned from Artemia onto live food at about 24 days after the onset of feeding without causing a reduction in growth and survival. The replacement of Artemia by Daphnia at day 10 appears feasible, as growth and survival were not significantly affected. Fish fed decapsulated Artemia cysts grew better than fish fed live Artemia. Within the first 14 days, goldfish juveniles should be fed at least 155 cysts per fish per day to achieve fast growth and to minimize size variation.     

Weaning of Wild Young-of-the-Year Winter Flounder Pleuronectes americanus (Walbaum) on a Dry Diet: Effects on Growth, Survival, and Feed Efficiency Ratios

Winter flounder Pleuronectes americanus is being developed for aquaculture in Atlantic Canada. Weaning, the switch from a live diet to formulated feed, is a critical stage in the culture of any fish species. In this study, we used wild young-of-the-year stock to determine whether juvenile winter flounder can be weaned from live, cultured Artemia onto dry feed. The dry feed used was originally formulated for turbot Scophthalmus maximus and cod Gadus morhua by BP Nutrition, Stavanger, Norway. The performance of live feed and dry pellets was compared in terms of survival, growth and feed efficiency over three months. We were able to wean wild juvenile winter flounder onto dry feed after one week. Increased specific growth rates and feed efficiency ratios in weaned juveniles indicated that prepared diet was a better food source than Anemia . Survival was not influenced by food type.     

Improving initial survival in cultured seahorses, Hippocampus abdominalis Leeson, 1827 (Teleostei: Syngnathidae)

This investigation aimed at improving early juvenile survival in cultured seahorses, Hippocampus abdominalis. Phototaxis from birth until 2 months of age was tested and juveniles were found to be positively phototactic within this age range. A comparison of the effect of culture vessel background (white vs. black vs. clear jars) on feeding efficiency at 1 week and 1 month of age using Artemia as prey revealed an age-dependent effect upon both attack rate and capture success. At 1 week, both attack rate and capture success were higher for juveniles contained in clear jars, and capture success was higher in black jars, as compared with white jars. At 1 month, there was no significant difference in attack rate between different jars, although capture success was higher in clear and white jars than in black jars. In a top-illuminated glass aquarium, juveniles with access to the water surface had lower survival (mean±1 SE=50±4.5%) than those without access to the water surface (73.3±4.2%). This was due to the ingestion of air bubbles when preying on Artemia nauplii congregating near the water surface. For side-illumination there was no such difference. Glass aquaria that were side-illuminated and blacked-off upwards from the waterline supported high juvenile survival (80.4±4.0% per brood) from birth through to 2 months of age in four broods.     

Influence of different food sources on the initial development of sexual recruits of reefbuilding corals in aquaculture

In coral aquaculture, sexual reproduction increasingly plays an important role for serving trade and reef restoration purposes. However, until coral juveniles reach a semi-stable size which makes them less vulnerable against algal growth and sedimentation, high mortality rates may occur in the first several weeks to months after settlement. In the present study, the influence of several food sources on the growth and survival of newly settled primary polyps was studied under laboratory conditions for 5 months. In order to estimate effects on specimens of both reproductive modes, experiments were carried out with the brooder, Favia fragum, and with the broadcast spawner, Acropora tenuis. Primary polyps kept in 2-liter aquaria were daily fed with freshly hatched Artemia salina, the micro algae Phaeodactylum tricornutum and a commercially available dry food (Nori Micro, Zoolife®), respectively, at various concentrations. Growth rates in both species were significantly higher in the Artemia treatment with maximum rates of 9.4 ± 4.9 mm² (mean ± S.D.; d = 5 months) for F. fragum and 26.8 ± 10.3 mm² (d = 5 months) for A. tenuis compared to all other treatments and the control (no additional food). Survival in F. fragum was overall higher than 60% in all treatments with maximum rates of 85.0 ± 12.6% at the highest Artemia concentration. Survival rates in A. tenuis ranged from 28.9 ± 4.7% (lowest Nori concentration) to 86.2 ± 5.9% (medium Artemia concentration). The present study shows that Artemia nauplii may greatly enhance the growth and partly enhance the survival of early sexual recruits which may significantly help to more rapidly overcome the early and most fragile post-settlement stages. As a consequence, the residence time for sexual coral recruits in cost- and labour-intensive hatcheries may be greatly reduced.     

Artemia enriched with high n-3 HUFA may give a large improvement in performance of Atlantic halibut (Hippoglossus hippoglossus L.) larvae

Atlantic halibut larvae were fed Artemia enriched with two different oil emulsions (cod liver oil and 2050TG) from first feeding to 70 days after first-feeding (dpff). Larvae fed 2050TG enriched Artemia had better growth, survival and eye migration than larvae fed the cod liver oil enriched Artemia, while pigmentation rate was similar in the two groups. In addition to the difference in fatty acids, the two emulsions differed in lipid class composition, since 2050TG is a synthetic oil and a mixture of mono-, di- and tri-acylglycerol, while cod liver oil is a tri-acylglycerol. Total lipid level, estimated as fatty acid methyl esters (FAME) was similar in the two Artemia types, but sum of n-6 and n-3 fatty acids, arachidonic acid (20:4n-6, ARA), docosahexaenoic acid (22:6n-3, DHA) and eicosapentaenoic acid (20:5n-3, EPA) were higher in Artemia enriched with 2050TG than in the cod liver oil enriched Artemia. However, the main difference in fatty acid composition in the larvae, was a higher DHA (% of total fatty acids) in 2050TG larvae than in cod liver oil larvae. The lipid level measured as FAME was up to four times higher in the 2050TG larvae than in the cod liver oil larvae, and the reason for this may have been a better bioavailability of the partly digested lipid in the 2050TG emulsion. The correlation between a high level of lipid in the larval tissues (e.g. high energy status) and improved eye migration in larvae fed the 2050TG enriched Artemia supports the hypothesis that energy limitation on the larval stage may be a cause of the impaired eye migration commonly observed in farmed Atlantic halibut juveniles.     

Effect of docosahexaenoic acid enrichment in Artemia on growth of Pacific bluefin tuna Thunnus orientalis larvae

Feeding enriched Artemia induces growth failure in Pacific bluefin tuna (PBT) Thunnus orientalis larvae; however, feeding of yolk-sac larvae of marine fish promotes larval growth. It is considered that this growth failure partly results from dietary docosahexaenoic acid (22:6n-3, DHA) deficiency. Therefore, we examined the effect of DHA contents in enriched Artemia on the growth of PBT larvae. Artemia nauplii were enriched with graded levels of DHA ethyl ester, and fed to PBT larvae for 9 days. Yolk-sac larvae of Japanese parrotfish Oplegnathus fasciatus were used as a reference diet. The DHA contents in Artemia increased with the enrichment from 0 mg g^− 1 dry weight basis (DW) to 25 mg g^− 1 DW, while the content in the reference diet was 21 mg g^− 1 DW. Feeding of enriched Artemia significantly improved the growth of PBT larvae. However, this improvement was negligible when compared with the excellent growth of the larvae that were fed the reference diet. PBT larvae that were fed the reference diet accumulated approximately twice or much higher levels of DHA in the neutral and polar lipids in the body when compared with the larvae that were fed enriched Artemia. These results show that PBT larval growth cannot be promoted by feeding enriched Artemia even if the DHA contents in Artemia are elevated to the same levels as those of yolk-sac larvae. The incorporation of dietary DHA into phospholipids in the fish body may be desirable for the normal growth of PBT larvae.     

Combined effect of weaning time and co‐feeding duration on growth and survival of peled Coregonus peled (Gmelin) larvae

The study investigated the combined effect of weaning from live feed to a commercial dry pellet at 10, 15, 20, 25 or 30 days posthatching (dph) and co‐feeding for 1, 3 or 6 days on survival and growth of Coregonus peled larvae. Additional groups fed only live Artemia sp. nauplii (ART), and only Biomar LARVIVA ProWean 100 (DRY) were included. A final survival rate of 66.4%–85.5% was observed in groups weaned after 20 dph. Final body weight (BW) and total length (TL) were significantly lower in groups weaned at 10 and 15 dph, regardless of the duration of co‐feeding. Larvae reached 29–37 mg BW and TL of 17.7–19.0 mm in groups weaned at 20, 25 and 30 dph. The recommended minimum duration of feeding with live food, based on these results, is 20 days. Based on the significantly higher yield of larvae weaned after 20 dph irrespective of co‐feeding duration, it can be concluded that abrupt weaning to dry food after 20 days of feeding with live prey can provide adequate production while reducing the effort and costs associated with live feed.     

Feeding trials with hatchery produced white sturgeon juveniles (Acipenser transmontanus)

Growth and survival of white sturgeon larvae were examined at ad libitum feeding with three commercial salmonid diets, and experimental crustacean diet, and a live food control (cubifex). The results demonstrated that some manufactured diets, particularly a semi-moist ration, can be used to rear white sturgeon during the first 40 days of feeding. Although specific growth rates of fish fed a semi-moist feed were 40% lower than those fed live foods, survival rates were similar. The high mortality previously associated with later transfer of fish from live foods to manufactured diets was avoided. Dry diets were not well accepted and resulted in lower rates of growth and survival.     

Growth,survival rate and fatty acid composition of sterlet (Acipenser ruthenus) larvae fed fatty acid‐enriched Artemia nauplii

We evaluated the growth and survival rate of sterlet (Acipenser ruthenus) larvae fed Artemia nauplii enriched with Olioω3 or Red Pepper commercial emulsions (BernAqua NV, Belgium). Sterlet larvae, 0.022 ± 0.002 g body weight, were randomly assigned to one of three feeding regimes with two different feeding durations. After administering live feed for 7 or 14 days, larvae were weaned onto commercial food and reared to 36 days posthatching (28 days of feeding). There were no significant differences in body weight among groups at the end of the trial. A significantly higher survival rate (p < 0.05) was observed in larvae fed Artemia enriched with Red Pepper for 14 days compared to other feeding regimes. Based on the analysis of growth parameters, we can conclude that 7 days of live feeding to be sufficient for efficient rearing of sterlet larvae. And longer duration of live feeding with use of special enrichment can be recommended for a higher survival rate.     

Use of formulated diets as replacements for Artemia in the rearing of juvenile American lobsters (Homarus americanus)

American lobsters, Homarus americanus, have been successfully reared in hatchery operations for over a century, yet formulated diets have never been commercially produced. In recent years, commercial Artemia replacement (CAR) diets have been developed and marketed for use in aquaculture production of marine shrimp. Three separate experiments assessed the utility of rearing American lobsters on these shrimp CAR diets. First, survival and growth of stage IV American lobsters fed one of three CAR diets (Artemac 5, CAR1; Economac 4, CAR2; and Progression 3, CAR3) were compared to those of animals fed frozen adult n-3 fatty acid enriched Artemia. Survival to 3 months was highest for animals fed CAR3 (85%), while animals fed Artemia had the greatest weight gain (> 6 % day^− 1). A cost / benefit ratio analysis showed that CAR2 was the most cost efficient for juvenile production because of its low overall purchase cost. Second, stage IV lobsters were fed either CAR2 or frozen adult n-3 fatty acid enriched Artemia exclusively, or in combination (2 : 5, and 5 : 2). Again, CAR2 was a cost effective feed to use, even as a partial replacement for Artemia. Survival was higher in diets that included CAR2, and feeding it two days per week compensated for low quality Artemia. Finally, 1.5 year old lobsters fed a gelatin-bound mix of 80% CAR2 and 20% frozen Artemia for five months survived and grew equally well compared to lobsters fed gelatin-bound frozen adult Artemia, and better than a custom formulated maintenance diet. The benefits of incorporating formulated feeds into American lobster rearing programs to increase the effectiveness of enhancement programs is discussed.     

Infection and mortality by the yeast Metschnikowia bicuspidata var. bicuspidata in chinook salmon fed live adult brine shrimp (Artemia franciscana)

First-feeding chinook salmon were fed either live adult Artemia franciscana or commercial feed over a 15-week period. Unexplained mortality began occurring in the Artemia-fed fish after 35 days on the diets, with cumulative mortality reaching 34.5% in the Artemia-fed fish compared with 4.3% in feed-fed fish. Necropsy examinations revealed systemic fungal yeast infections and the causative agent was cultured from kidneys. Fungal cells were observed in the transport water of Artemia shipments and within the Artemia. The Artemia were purchased from a retail supplier, and originated from salt ponds in San Francisco Bay (SFB), California. Artemia infection rates ranged from 0.5% to 37.5% (mean 16.5±3.59%) in shipments received over a 5-week period. The fungus was characterized by morphological and physiological properties and was identified as Metschnikowia sp., a pathogenic yeast of aquatic invertebrates. The yeast grew at 9–27 °C, and 0–180 ppt NaCl, and could tolerate salinity of at least 270 ppt. Sequence analysis of the divergent D1/D2 domain of ascomycetous yeast 26S ribosomal DNA identified the organism as Metschnikowia bicuspidata var. bicuspidata. The organism was found in water from the salt ponds and probably entered from the bay. Mortality due to the fungal infection stopped after changes were made in the handling of incoming Artemia shipments.     

The impact of nutrition on metamorphosis in Atlantic halibut (Hippoglossus hippoglossus L.)

Fatty acids, vitamin A and thyroid hormone have all been shown to affect development of flatfish larvae and they are ligands to nuclear receptors that participate in the control of development. Our hypothesis was that one of these factors or an interaction between them may be the cause of abnormal development of flatfish larvae. Atlantic halibut larvae were fed either DHA-selco-enriched Artemia or copepods from first feeding. In fish that had been fed Artemia, only 7% had normal pigmentation and 10% normal eye migration. The numbers for fish fed copepods were 68% and 88%, respectively. Malpigmented fish fed Artemia were depigmented, while those fed copepods had ambicoloration. The differences in development were probably nutrient dependent, since all other conditions were similar for the two groups. Larvae fed copepods had markedly higher body levels of docosahexanoic acid (DHA, 22:6n−3) and eicosapentaenoic acid (EPA, 20:5n−3) and lower levels of arachidonic acid (ARA, 20:4 n−6) than larvae fed Artemia. The DHA/EPA ratio was similar in the two groups, but the EPA/ARA ratio was more than four times higher in larvae fed copepods than in larvae fed Artemia. Larvae fed copepods had higher body levels of total retinol than larvae fed Artemia, but the difference was due to higher levels of the storage forms, retinyl esters, whereas the levels of free retinol and retinal were similar in the two groups. The level of iodine was 700 times higher in copepods than in Artemia and 3–4 times higher in larvae fed copepods than in larvae fed Artemia. There was a significantly higher level of T₄ in larvae fed copepods during the “window of opportunity”, 15–30 days after first feeding. In an experiment where Atlantic halibut larvae were fed Artemia enriched in iodine up to the levels found in copepods, there was a significant effect on the body level of iodine and a non-significant tendency of higher levels of thyroid hormone, but no effect on pigmentation or eye migration. It is concluded that Artemia probably offers a sufficient access to vitamin A precursors to meet the larval requirement. More research should be done to elucidate possible effects of iodine on development of Atlantic halibut larvae. Fatty acid composition is still the most likely candidate for causing abnormal development in Atlantic halibut larvae.     

A successful microbound diet for the larval culture of freshwater prawn Macrobrachium rosenbergii

A high moisture (63–71%), semi-purified microbound diet containing alginate was compared to newly hatched live Artemia nauplii as an exclusive diet for the culture of larval freshwater prawn Macrobrachium rosenbergii from 5th stage (weighted mean) through metamorphosis to postlarva. Two separate trials, representing larvae from different hatches, were conducted. Larvae were stocked at 50/l into cone-shaped vessels that contained 2 l of 12‰ seawater and were part of a temperature-controlled (28 °C) recirculating culture system. Larvae were manually fed either the live Artemia diet or the microbound diet exclusively, several times daily. After 14 days (23 days post-hatch (dph)), growth of larvae fed the microbound diet was 90% of that achieved for larvae fed newly hatched nauplii of Artemia. Survival of larvae fed the microbound diet was 77.3% and 73.3%, and was not significantly different from that of Artemia-fed larvae. Composed of readily available ingredients, the diet contains 46.2% crude protein and 37.4% lipid, is easy to prepare, and has good water stability. The diet is an economically practical alternative to the fluctuating cost, nutrient uncertainty, and labor associated with the use of Artemia nauplii hatched from cysts. The characteristics of the diet suggest good potential for successful use in the larviculture of other fish and crustacean species, in either the existing or a modified state.     

Weaning Chinese perch Siniperca chuatsi (Basilewsky) onto artificial diets based upon its specific sensory modality in feeding

Chinese perch are one of the most valuable food fish in China, but the sole source of feed for intensive culture is live prey fish. Our previous studies on systematic sensory physiology revealed that this species have a mechanism for this peculiar feeding habit. In the present study, a specific training procedure was designed, and both experimental (initial body weight 171.0 g; 120 days) and commercial (initial body weight 52.4 g; 240 days) net-cage cultures were conducted to investigate the training success, growth performance and survival of the trained yearlings fed with nonlive or Oregon-type moist diet. The training successes of minced prey fish and the Oregon moist diet were 100 and 89.9%, respectively, in experimental culture, and 92.2 and 83.5% in commercial culture. In an experimental trial, the fish fed minced prey fish or the Oregon moist diet attained final body weights of 472.7 g or 344.7 g, although the specific growth rates of these groups were significantly lower than that of the fish fed live prey fish (final body weight 560.0 g). Mortality was not significantly related to dietary treatment. In commercial culture, the final body weights were as follows: 750 g on live prey fish, 705 g on minced prey fish and 651 g on the Oregon moist diet. Feed costs to produce 1 kg fish were estimated to be US$6.59 for live prey fish, US$1.76 for minced prey fish and US$2.07 for the Oregon moist diet. The results of the present study confirmed that sensory modality and associative learning appear to be critical factors in determining food discrimination of Chinese perch, indicating that both minced trash fish and Oregon-type moist diet can be substituted for live prey fish in intensive commercial production.     

Growth performance,survival, feed utilization and nutrient utilization of African catfish (Clarias gariepinus) larvae co‐fed Artemia and a micro‐diet containing freshwater atyid shrimp (Caridina nilotica) during weaning

Problems of limited number of dry feeds as supplement or replacement of live feeds have led to poor larval nutrition in many species of fish. Therefore, the suitability of co‐feeding 8‐day‐old African catfish (Clarias gariepinus) posthatch larvae using live feed (Artemia salina) and formulated dry diet containing freshwater atyid shrimp (Caridina nilotica) during weaning was investigated. The experiment ended after 21 days of culture and respective groups compared on the basis of growth performance, survival, feed utilization and nutrient utilization. Larvae co‐fed using 50%Artemia and 50% formulated dry diet resulted in significantly (P < 0.05) better growth performance, food gain ratio (FGR), protein efficiency ratio (PER) and productive protein values (PPV) than other treatments. The lowest growth performance occurred in larvae weaned using 100% formulated and commercial dry diets. Better survival of over 90% was obtained in larvae weaned using 50%Artemia and 50% dry diet, while abrupt weaning using 100% dry diets resulted in lower survival (<75%). These results support a recommendation of co‐feeding C. gariepinus larvae using a formulated dry diet containing C. nilotica and 50% live feed when weaning is performed after 8 days posthatching period.     

Influence de la photoperiode sur la croissance et la survie de la larve et du juvenile de sole (Solea solea) en elevage

The effect of photoperiod on survival and growth of cultured young soles (Solea solea) was investigated from hatching to the age of three months, at 18° C. Two experiments were performed, comparing days with 12, 18 and 24 h light. The fishes were reared in 60 1 tanks, conical ones before metamorphosis, square ones with a sandy bottom from metamorphosis to the age of three months. They were fed on live food organisms for 1 month, on frozen flesh of the bivalve Laevicardium crassum for the two other ones.During the larval period, no significant difference was recorded in the survival rate but a better growth was obtained with 18 and 24 h light, suggesting a predominant diurnal feeding. From metamorphosis to the age of three months (mean weight: 1 g) no significant effect of the photoperiod on the survival and growth of the juveniles could be demonstrated.     

Effects of food availability on feeding and growth of cultivated juvenile Babylonia formosae habei (Altena & Gittenberger 1981)

Juveniles of the scavenging gastropod Babylonia formosae habei ( Altena & Gittenberger 1981 ) were kept at different ration levels in the laboratory for 30 days. Feeding behaviour and growth performance of the juveniles in relation to food availability were studied. Babylonia formosae habei juveniles were exposed to one of the four ration levels with food provided once either every 1, 2, 5 or 10 days. Higher food consumption, longer time spent on feeding and higher percentage of feeding individuals were obtained in individuals maintained at lower ration levels. Similar growth performances were observed in individuals fed once every day or every two days. A sustained production of shell was obtained in the juveniles maintained at low ration levels. At the end of the experiment, lower protein and lipid content as well as lower energy content were measured in the somatic tissue of juveniles maintained at lower ration levels. During the 30‐day experiment, food availability is not a crucial factor on survival of juvenile B. formosae habei due to its physiological and behavioural adaptations developed in association with starvation.     

Early weaning of winter flounder (Pseudopleuronectes americanus Walbaum) larvae on a commercial microencapsulated diet

Like most small marine fish larvae, the stomachs of winter flounder Pseudopleuronectes americanus are undeveloped at first feeding and have relatively reduced digestive capacity. This work was undertaken to test whether larvae at the onset of stomach differentiation (larval size about 5.5 mm) could be early weaned onto a commercial microencapsulated diet. We assessed the effect of early weaning by first comparing growth performance (standard length, total protein content and age at metamorphosis) of larvae fed enriched live prey from first feeding to a size of 5.5 mm and then reared on three different feeding regimes until metamorphosis: (1) live prey (LP) as a control group; (2) mixed feeding of live prey and microencapsulated diet (LP‐ME); (3) exclusively microencapsulated diet (ME) after fast weaning over 4 days (to a larval size of 6.2 mm). No differences were observed between larval development in the two first groups, which began metamorphosis at 40 days old. The larvae of the third group showed significantly slower growth that resulted in a delay of 4 days in the onset of metamorphosis. Differences in live prey availability between the treatments and the short transition period to allow the larvae to adapt to the new diet were identified as possible contributing factors to the slower growth and to the delay in metamorphosis of early weaned larvae. In a second experiment, the transitional weaning period was increased until the larvae were 6.6 mm in length. Weaning at that size resulted in no slowing of growth or delay in metamorphosis, suggesting that the feeding schedule was adequate.