Establishing larval feeding regimens for the Forktail Blenny Meiacanthus atrodorsalis (Günther, 1877): effects of Artemia strain,time of prey switch and co‐feeding period

This study aimed to establish feeding strategies covering the whole larval period of the forktail blenny, Meiacanthus atrodorsalis, based on the standard hatchery feeds of rotifers and Artemia. Three purposely designed experiments were conducted to determine the appropriate times and techniques to transition larvae from rotifers onto Artemia nauplii of a Great Salt Lake (GSL) strain, and a specialty AF strain, as well as subsequent transition onto enriched metanauplii of GSL Artemia. With a 3‐day co‐feeding period, larvae adapted well to a transition from rotifers to newly hatched GSL Artemia nauplii as early as 5 days posthatching (DPH), and as early as 3 DPH when fed the smaller AF Artemia nauplii. However, prolonging the rotifer‐feeding period up to 11 DPH did not negatively affect survival. Larvae fed Artemia nauplii of the AF strain showed 17–21% higher survival, 24–33% greater standard length and body depth, and 91–200% greater dry weight, after 20 days relative to those fed nauplii of the GSL strain. Meanwhile, enriched Artemia metanauplii of the GSL strain were shown to be an acceptable alternative to AF Artemia nauplii for later larvae, producing similar survival and growth when introduced from 8 DPH. Based on our findings, we recommend feeding M. atrodorsalis larvae rotifers as a first food between 0 and 2 DPH, introducing AF Artemia nauplii from 3 DPH, followed by enriched GSL Artemia metanauplii from 8 DPH onward, with a 3‐day co‐feeding period between each prey change.     

Slightly salinized water enhances the growth and survival of Arapaima gigas larvae

The aim of this study was to evaluate the survival and growth of Arapaima gigas larvae reared in slightly salinized water. Pirarucu larvae (183.1 ± 41.2 mg and 3.4 ± 0.3 cm) were stocked in PVC tanks (20 L; n = 4; 40 larvae per tank) in a static system. A. gigas larvae were reared in increasing levels of salinized water (0, 1, 2, 3 and 4‰) for a period of 15 days. Fish were fed six times a day with Artemia nauplii (2,900 nauplii per larvae per meal in the beginning). The salinized water increased by at least four times the Artemia nauplii lifespan, which prolonged the time of live food supply to Arapaima larvae. Pirarucu larvae kept in freshwater presented the lowest values in weight gain, final weight and survival. Larvae reared in water with 4‰ of salinized water showed the highest final weight. Slightly salinized water enhances the growth and survival of A. gigas larvae and it can be a simple practice with low cost that can be applied in the routine of pirarucu larviculture.     

Food consumption and selectivity by larval yellowtail kingfish Seriola lalandi cultured at different live feed densities

Live food supply is a key factor contributing to the success of larval fish rearing. However, live food densities vary greatly between fish species and management protocols across fish hatcheries. The growth, survival, food selection and consumption of yellowtail kingfish larvae were examined at different regimes of live food supply in an attempt to identify a suitable live food feeding protocol for larval rearing in marine fish. This study was divided into two feeding phases: rotifer phase from 3 to 14 DPH (phase I) and Artemia nauplii phase from 15 to 22 DPH (phase II). In phase I, four rotifer densities (1, 10, 20 and 40 mL⁻¹) were used. In phase II, Artemia started at 0.8 nauplii mL⁻¹ on 15 DPH, and then the density of Artemia was daily incremented by 50%, 70%, 90% and 110%, respectively, in four treatments from 15 to 22 DPH. In phase I, rotifer density significantly affected larval growth, but not survival. By 7 DPH, the number of rotifers consumed by fish larvae reached 170–260 individuals, but did not significantly differ between rotifer densities. During cofeeding, fish larvae selected against Artemia nauplii by 10 DPH, but by 14 DPH Artemia nauplii became the preferred prey item by fish larvae exposed to the 10, 20 and 40 rotifers mL⁻¹. In phase II, both fish growth and survival were affected by Artemia densities. Fish daily consumption on Artemia by 20 DPH reached 500–600 individuals but did not significantly differ between prey densities. The result suggests that rotifer densities be offered at 20–40 mL⁻¹ before 6 DPH and 10–20 mL⁻¹ afterwards to support larval fish growth and survival. Likewise, Artemia is recommended at a daily increment of 90–110% of 0.8 mL⁻¹ from 15 to 22 DPH. This study proposes a management protocol to use appropriate type and quantity of live food to feed yellowtail kingfish larvae, which could be applicable to larval culture of other similar marine fish species.     

Preliminary study on the activity of protease enzymes in Persian sturgeon (Acipenser persicus Borodin, 1897) larvae in response to different diets: effects on growth and survival

The specific activity of alkaline protease, trypsin and pepsin‐like enzymes was measured in yolk sac stage Acipenser persicus larvae and over a 1‐month feeding experiment using live Artemia nauplii (ND), formulated feed (FD) or mixed food (MD). Artemia nauplii group larvae showed significantly higher growth and survival during the first 15 days while FD larvae showed the lowest growth and survival. At day 30, MD larvae exhibited significantly higher growth than the ND group. Alkaline protease activity showed the lowest activity on day 15; the highest activity was observed in the MD group larvae. Pepsin‐like activity showed a drastic increase from day 1 to 5 in all treatments, but remained stable throughout the next 25 days, with the lowest and the highest activity in the FD treatment on day 10 and in the MD treatment on day 30 post‐feeding respectively. Trypsin‐like activity in group ND remained almost the same from day 5 to 30, whereas in groups MD and FD, it decreased significantly from day 10 to 30. The contribution of the naupliar proteases was moderate but effective. Additionally, better performance in Artemia fed sturgeon larvae may also be due to the structure and digestibility of proteins and the food intake stimulation by the nauplii.     

Effect of Rearing Density and Feeding Regimes on Growth and Survival of African Catfish,Heterobranchus longifilis (Valenceinnes, 1840) Larvae in a Closed Recirculating Aquaculture System

Heterobranchus longifilis larvae were reared over a 35 d period to evaluate the effects of stocking densities and feeding regimes on growth and survival. In experiment 1, larvae (12.3?±?2.1 mg) were stocked into glass aquaria at densities of 1, 2, 5, 10, 15, 20, and 25 larvae L^?1. Larvae were fed on Artemia nauplii ad libitum. Significant variations in terms of growth performance and feed utilization occurred at all levels of density treatments. Specific growth rate (SGR), body weight gain (BWG), and feed efficiency (FE) of the larvae decreased significantly as density increased. However, survival rate increased with the increase of stocking density. In experiment 2, larvae (13.4?±?1.1 mg) stocked at a density of 15 larvae L^?1, in the same conditions as experiment 1, were fed on three different regimes: Artemia nauplii; 35%?protein beef brain; and 35%?protein commercial catfish feed (CN⁺). SGR, BWG, and coefficient of variation (CV) of larvae fed on Artemia nauplii were significantly higher than those fed on beef brain and CN⁺. The survival rate of larvae fed on beef brain was significantly higher (88.40?±?9.75%) than those of Artemia (69.21?±?6.69%) and CN⁺ (40.40?±?6.22%). The results of this study suggest that the optimum stocking density is 15 larvae L^?1 and the beef brain can be used as alternative feed to Artemia in rearing H. longifilis larvae.     

Effect of Salinity on Larval Rearing of Pacu,Piaractus mesopotamicus,a Freshwater Species

The aim of this study was to evaluate the growth and survival of pacu, Piaractus mesopotamicus, larvae reared in different salinities and to determine the Artemia nauplii life span in freshwater and in saline water. First feeding 5‐d‐old pacu larvae were reared in freshwater or at 2, 4, 6, 8, 10, 12, and 14 ppt salinities. The larvae were reared in 1.5‐L aquaria at a density of 10 larvae/L with three replicates per treatment. After 10 d of rearing, significant differences (P < 0.05) were observed for growth and survival. Larval growth was higher at 2 and 4 ppt, and survival at 2 ppt was 100%. In freshwater and at 4, 6 and 8 ppt, the survival was 91.1, 93.3, 73.3, and 39.9%, respectively. At higher salinities, there was 100% mortality after 2 h (12 and 14 ppt) and 8 h (10 ppt) of exposure. The slightly saline water of at least 2 ppt increased the Artemia nauplii life span compared to the life span in freshwater. Later, in a second trial, 5‐d‐old pacu larvae were reared in freshwater and at 2 and 4 ppt salinities during the first 5 or 10 d of active feeding, and then the fish were transferred to freshwater. At the end of 15 d, larval growth was lower in freshwater (42 mg) than in treatments 2 and 4 ppt (59–63 mg). The abrupt transfer of fish from freshwater to slightly saline water and the return to freshwater did not affect the survival rates (89–97%). The larvae were able to adapt to these saline environments and handle abrupt changes in salt concentration. We concluded that salinity concentration of 2 ppt can be used for pacu larval rearing, allowing the Artemia nauplii lifetime to last longer and cause faster fish growth.     

The Predation of Artemia Nauplii by the Larvae of the Amazon River Prawn,Macrobrachium amazonicum (Heller, 1862), is Affected by Prey Density,Time of Day,and Ontogenetic Development

The present study analyzed the effects of prey density, the time of day, and ontogenetic development on the predation of Artemia nauplii by the larvae of the Amazon river prawn, Macrobrachium amazonicum, as well as possible synergy among these factors. Larvae were raised in 120‐L tanks with biological filter systems, and fed on recently hatched Artemia nauplii, using two feeding management protocols: (a) fed once per day at 2000 h (high density – HD) and (b) half of the ration provided at 2000 h, complemented at 0800 h the following day by a replacement of the nauplii consumed up to a maximum of the full ration (low density with replacement – LDWR). Each treatment consisted of six replicates. The consumption of nauplii was estimated prior to the feeding times. Consumption varied according to time of day, ontogenetic development, and feeding protocol. The larvae ingested more nauplii during the daytime at most developmental stages. Ingestion rates were similar during the day under both treatments, but at night the higher density of prey in the HD treatment caused a higher encounter rate and increased ingestion of nauplii by the larvae. Among the performance indicators only survival was greater in HD in comparison with LDWR; productivity and dry weight were similar. The results indicate a circadian trophic rhythm in M. amazonicum, with the encounter rate being an important mechanism for the capture of prey during the night. A second mechanism – probably the visual system – aids the perception of prey during the daytime. Based on these results, we suggest that feeding captive Amazon river prawn larvae only once a day would be appropriate and economically beneficial. Further work is necessary to determine the most effective time that this single feed should be applied.     

A Comparison of Growth,Survival, and Fatty Acid Composition of the Lined Seahorse,Hippocampus erectus,Juveniles Fed Enriched Artemia and a Calanoid Copepod,Schmackeria dubia

The purpose of this study was to evaluate the effect of varying dietary levels of highly unsaturated fatty acids (HUFAs) in live prey (Artemia nauplii and a calanoid copepod, Schmackeria dubia) on the growth performance, survival, and fatty acid composition of the lined seahorse, Hippocampus erectus, juveniles. Artemia nauplii were enriched with a commercial product (SS^? 50DE‐microcapsule as HUFA source, 2/3 DHA, 1/3 EPA. Shengsuo Fishery Feed Research Center of Shandong Province, Qingdao, China) at four concentrations of 0.0, 14.0, 28.0, and 56.0. Newly hatched juveniles were cultured for 35 days. The content of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and n‐3 HUFAs in the Artemia nauplii was positively related to the enrichment concentration. At the end of the trials, growth performance of the juveniles was positively related to the enrichment concentration as well. However, the juveniles fed prey enriched with the highest concentration of enrichment (56.0 μL/L) had the significantly lower (P < 0.05) survival rate. The juveniles fed the copepod had the best growth performance and the highest survival rate, suggesting that the copepod, S. dubia, is suitable for feeding the seahorse juveniles. The comparisons between the growth, survival, and fatty acid profiles of the juveniles fed Artemia and copepods indicate that the seahorse juveniles require dietary levels of DHA beyond those achieved by enriching prey with the HUFA enrichment. Surplus EPA resulted from an imbalance between DHA and EPA in the enriched Artemia nauplii probably caused an adverse effect on the seahorse juveniles. This study suggests that DHA and EPA requirement of the lined seahorse juveniles is roughly 32% of total fatty acid, and the optimal DHA/EPA ratio for the species is circa 4:1. To avoid an adverse effect resulting from excessive EPA, maximum proportion of EPA in enriched Artemia nauplii should not exceed 13% of total fatty acid, and a recommended minimum DHA/EPA ratio in the enriched Artemia nauplii is 1.46. Arachidonic acid (20:4n‐6) might not be an essential fatty acid for the seahorse juveniles.     

Decapsulated Artemia Cysts: A Suitable Dietary Supplement for Juvenile Tench (Tinca tinca L.)

There are no specifically formulated dry foods for tench (Tinca tinca L.), which forces farmers to use diets formulated for other fish species. This has major drawbacks, such as high mortality, slow growth, and body deformities. A 120 day experiment was performed with five-month-old juvenile tench (initial mean weight: 0.388 g; total length: 31.78 mm) to evaluate decapsulated Artemia cysts as a supplement to a dry diet for other fish species. Three treatments, differing in the daily supplement, were tested: 1,800 freshly hatched nauplii, 1,800 cysts, and 300 cysts per g of tench biomass. Final survival ranged between 95.3% and 97.9%. Juvenile tench that received the supplement of 1,800 decapsulated Artemia cysts had a specific growth rate (1.28), weight (1.83 g), and total length (52.30 mm) significantly higher than those with the same amount of nauplii. The lowest supplement (300 cysts/g of fish biomass) allowed significantly lower growth and higher condition coefficient (1.40) than the rest. Animals with body deformities (1.06%) were only recorded in the groups that received the lowest cyst supplement. Results showed Artemia cysts are a suitable dietary supplement for juvenile tench, being an advantageous alternative to live nauplii.     

Effects of enriched Artemia nauplii on production, survival and growth of the mysid shrimp Mysidopsis almyra Bowman 1964 (Crustacea: Mysidacea)

The effects of enriched Artemia nauplii on larvae production and survival and growth of the mysid Mysidopsis almyra Bowman 1964 are compared. There were no significant differences (P > 0.05) in production between mysids fed the Artemia nauplii (133 ± 69 mysids day⁻¹) and mysids fed the enriched nauplii (139 ± 82 mysids day⁻¹). No differences in size of newly hatched mysids or mysid growth to 15 days (P > 0.05) were found between the two diets. Survival was significantly higher (P < 0.05) for mysids fed the enriched nauplii (59.1%) compared with mysids fed Artemia nauplii (41.4%).     

Effects of diet transition regimen on survival, growth and lipid composition of intensively reared Atlantic cod, Gadus morhua, larvae

Replicated groups of Atlantic cod were rearedfor up to 40 days in 100 l tanks stocked at adensity of 75 eggs l^–1. Larvae weretransferred from rotifers, Brachionusplicatilis, to either fresh-hatched orenriched Artemia nauplii on each of days5, 15 and 25 post-hatch (ph). Rotifers wereprogressively withdrawn over a 5 day period.The type of Artemia offered(fresh-hatched, enriched) did not affectsurvival or growth rates at any of the 3transfer ages. Larvae transferred toArtemia from day 5 ph suffered a highincidence of swimbladder over-inflation andhigh mortality during metamorphosis (< 1%survival to day 36 ph). Cod in the day 15 and day25 transfer groups did not differ significantlyin weight-specific growth rate or size on day40 ph (mean standard length 13.8 mm, dry weight3.8 mg). Highest mean survival rates to day 40ph (18.1%) and lowest mortality followingtransfer to nursery tanks were also observed inthe day 25 transfer groups. Fish that receivedArtemia from day 5 ph containedcirca twice as much total lipid per unit bodyweight and had a 30% higher triacylglycerol(TAG) content compared to all other groups.Ratios of the essential fatty acidsdocosahexaenoic acid (DHA), eicosapentaenoicacid (EPA) and arachidonic acid (ARA) alsodiffered according to age-at-transition.DHA:EPA ratio exceeded 1 only in codtransferred to Artemia on day 25 ph.Based on these findings, it is recommended thatintensively reared Atlantic cod should continueto receive rotifers until completion ofmetamorphosis.     

Effect of different food items on the survival and growth of Farfantepenaeus paulensis (Pérez-Farfante 1967) postlarvae

The effect of different food items on growth and survival was assessed in four feeding experiments conducted consecutively using distinct Farfantepenaeus paulensis (Pérez‐Farfante) postlarval growing stages: (1) PL₁–PL₄ (i.e. from postlarvae 1‐day old to postlarvae 4 days old); and (2) PL₄–PL₁₀; (3) PL₁₀–PL₁₈ and (4) PL₁₈–PL₃₀. For each trial, 10 feeding treatments were tested in triplicate: Unf, unfed shrimp; Tt, Tetraselmis chuii; Ch, Chaetoceros calcitrans; C, commercial diet; AC, decapsulated Artemia cysts; C+Ph, commercial diet and phytoplankton combination; FA, frozen Artemia nauplii; A, live Artemia nauplii; A+Ph, Artemia nauplii and phytoplankton combination and Mix, mixture of phytoplankton, live Artemia nauplii and commercial diet. Postlarvae feed phytoplankton (i.e. Tt or Ch) exclusively exhibited low growth and survival. The best results for growth and survival were observed in the A, A+Ph and Mix treatments. Frozen Artemia nauplii was found to be suitable for younger postlarvae (PL_1–10), whereas AC may be offered from PL₄ to PL₃₀. In general, the present findings indicated that even at an early postlarval stage, F. paulensis presents a high degree of carnivory, and a diet containing Artemia is recommended.     

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.     

Encapsulation capacity of Artemia nauplii with customized probiotics for use in the cultivation of western king prawns (Penaeus latisulcatus Kishinouye, 1896)

The encapsulation capacity of Artemia nauplii with customized probiotics Pseudomonas synxantha and Pseudomonas aeruginosa for use in the cultivation of western king prawns (Penaeus latisulcatus) was investigated. Seven trials were conducted to investigate this encapsulation capacity in terms of Artemia survival and probiotic load in Artemia. Newly hatched Artemia nauplii at 250 nauplii mL^?1 were fed individual probiotics at 0, 10³, 10⁵ and 10⁷ colony‐forming units (CFU) per millilitre, and mixtures of these two probiotics (10⁵ CFU mL^?1) at 30:70, 50:50 or 70:30 v/v in a medium of ozonated water (OW), tryptone soya broth (TSB), and a mixture of these media. The appropriate medium for encapsulation of probiotics by Artemia nauplii was the mixture of OW and TSB at 75:25 v/v; whereas, the use of OW or TSB alone was not effective. Artemia nauplii most effectively encapsulated the customized probiotics at 10⁵ CFU mL^?1. The results indicates that the encapsulation of Artemia nauplii is optimized by using a combination of P. synxantha and P. aeruginosa at 50:50 v/v in a media mixture of OW and TSB at 75: 25 v/v. Artemia should be harvested at 48 h when survival is still high (78%) and the probiotic load in Artemia is high (3 × 10⁴ CFU nauplius^?1).     

Effect of enriched live feeds on survival and growth rates in larval Korean rockfish, Sebastes schlegeli Hilgendorf

High mortality frequently occurs in larval mass production of Korean rockfish, Sebastes schlegeli Hilgendorf. Nutritional deficiencies in live feeds, rotifers and Artemia nauplii, fed to larvae could be a reason. A series of experiments was carried out to evaluate the effect of nutritional enrichment of live feeds by ω‐yeast, Spirulina powder and Super Selco^TM on survival and growth rates in rockfish larvae. Preference of rockfish larvae for the live feeds was determined by analysis of stomach contents. In addition, the effect of green water produced by the use of Chlorella ellipsoidea and Spirulina powder on the growth performance of larvae was evaluated. Larvae fed rotifers nutritionally enriched with Super Selco showed significantly higher survival rates than those fed rotifers enriched with ω‐yeast. Larvae fed rotifers that were nutritionally enriched with both Super Selco and Spirulina together exhibited improved growth and survival rates. Larvae fed Artemia nauplii nutritionally enriched with Spirulina powder showed significantly higher survival than larvae fed Artemia nauplii without enrichment. When larvae were fed rotifers, Artemia nauplii or the mixture of rotifers and Artemia nauplii, the second and last group showed significantly higher survival than the first group. Fatty acid composition in live feeds was improved by enrichment of ω‐yeast and larvae fed this feed showed higher survival and growth rates compared with larvae fed non‐enriched feeds. No positive effect of green water in the tank produced with C. ellipsoidea or Spirulina powder was observed on survival and growth rates for larvae fed nutritionally enriched rotifers with Super Selco and Spirulina powder. However, when the larvae were fed Artemia nauplii that were nutritionally enriched with ω‐yeast and Spirulina powder, green water obtained by adding Spirulina powder to the tanks resulted in significantly higher growth rates of larvae than was obtained by adding C. ellipsoidea.     

Decapsulated Artemia cysts as dietary supplement for juvenile crayfish (Pacifastacus leniusculus, Astacidae) at different food supply frequencies from the onset of exogenous feeding under controlled conditions

Considering that the use of decapsulated Artemia cysts as direct food for juvenile crayfish could be an alternative to live nauplii, a 100-day experiment was carried out under controlled conditions to evaluate the effects of cysts, comparing with nauplii, as supplement to a dry diet for salmonids on the survival and growth of juvenile signal crayfish (Pacifastacus leniusculus) from the onset of exogenous feeding (stage 2). The reduction of feeding frequency was also tested. According to a bifactorial design, six treatments, differing in the supplement and feeding frequency, were tested: the dry diet supplemented with Artemia nauplii or decapsulated cysts was supplied once a day, once every two days and once every three days. Survival rates ranged from 56.7% to 81.7%, rising significantly with increasing the feeding frequency. The highest growth (12.94 mm carapace length and 593.08 mg weight) was reached by the crayfish that received the dry diet supplemented with cysts once a day, with significant differences from the rest of the treatments. Considering the supplement, the cysts supported significantly higher growth than the nauplii. Regarding the feeding frequency, growth was higher when the food was supplied once a day, showing significant differences from the other two frequencies (once every two days and once every three days). This study shows that decapsulated cysts are better dietary supplement than live nauplii. In crustacean culture, this is the first report of successful use of Artemia cysts from the onset of exogenous feeding.     

Effect of feeding scheme and prey density on survival and development of Chinese mitten crab Eriocheir sinensis zoea larvae

The effect of feeding scheme and prey density on survival and development of Eriocheir sinensis zoea larvae was studied in three experiments. Different combinations and densities of rotifers (Brachionus rotundiformis) and newly hatched Artemia nauplii were fed to zoea larvae. Average survival at each stage, larval development (larval stage index, LSI), duration of zoeal stage and individual megalopa dry weight were compared among treatments. This study revealed that, under the experimental conditions, rotifers should be replaced with Artemia between the zoea 3 (Z3) and the zoea 4 (Z4) stage. The optimal rotifer feeding densities for zoea 1 (Z1) and zoea 2 (Z2) were 15 and 20 mL^?1 respectively, while the optimal Artemia feeding density for Z3, Z4 and zoea 5 (Z5) was 3, 5 and 8 mL^?1 respectively. Further trials in production scale are recommended.     

Use of the microalga Nannochloropsis occulata in the rearing of newborn longsnout seahorse Hippocampus reidi (Syngnathidae) juveniles

The aim of this study was to evaluate the effect of microalgae on the rearing of newborn juveniles of the longsnout seahorse, Hippocampus reidi. Two treatments in three replicates were tested over a 15‐day period: with and without the addition of the microalgae Nannochloropsis oculata at a concentration of 2.02 ± 0.44 × 10⁶ cells mL^?1. At each replicate, beginning on the second day of life, 120 H. reidi juveniles (stocking density of 3 ind L^?1) were fed the offspring of the benthic copepod Tisbe biminiensis (100 copepod cm^?2) together with newly hatched Artemia nauplii (3.8 mL^?1). From the sixth day of life, enriched Artemia metanauplii replaced newly hatched Artemia nauplii. After 15 days, the H. reidi individuals were counted, measured and weighed. Mean survival was significantly greater in the microalgae treatment (76.42 ± 5.07%) than in the treatment with no microalgae (25.44 ± 6.91%). Moreover, total length, height and dry weight were significantly larger in the microalgae treatment. Thus, the addition of microalgae increases the growth and survival of H. reidi juveniles fed T. biminiensis and Artemia. The higher growth and survival of H. reidi juveniles was not related to the larger ingestion rates but probably to the nutritional improvement of the live feeds or to the probiotic effect. The protocol developed for rearing H. reidi juveniles resulted in a high survival, and represents an advance in the farming of this species.     

Effect of Temperature on Growth and Survival in Juvenile Opossum Pipefish,Microphis brachyurus: First Observations on the Species in Culture Conditions

In Mexico, natural populations of the opossum pipefish, Microphys brachyurus, are under pressure by anthropogenic alteration of their habitat and unregulated fishing as this species is traded as an aquarium fish, where its survival is low due to inadequate culture practices. The development of culturing techniques has been a successful strategy to protect many exploited species through providing an alternative source to wild exploitation. The aim of this study was to examine the effect on growth, condition, and survival of pipefish cultured for 6 wk at temperatures of 26, 28, and 30 C. Pipefish were fed enriched Artemia nauplii maintaining a ration rate of 14% body weight per day (dry weight Artemia : wet weight fish). The pipefish cultured at 26 and 28 C were longer, heavier, grew faster, and presented better condition than those at 30 C. The survival of pipefish cultured at 26 C was greater (83%) than at 30 C (30%) but not different than at 28 C (50%). This study is the first to report the acceptance of Artemia nauplii by juveniles of the species and that a temperature of 30 C is not suitable for juvenile M. brachyurus culture.     

Evaluation of partial replacement of live and fresh feeds with a formulated diet and the influence of weaning <Emphasis Type="Italic">Panulirus ornatus</Emphasis> phyllosomata onto a formulated diet during early ontogeny

We have evaluated the potential of a formulated diet as a replacement for live and fresh feeds for 7-day post-hatch Panulirus ornatus phyllosomata and also investigated the effect of conditioning phyllosomata for 14–21 days on live feeds prior to weaning onto a 100% formulated diet. In the first trial, the highest survival (>55%) was consistently shown by phyllosomata fed a diet consisting of a 50% combination of Artemia nauplii and 50% Greenshell mussel, followed by phyllosomata fed 50% Artemia nauplii and 50% formulated diet and, thirdly, by those receiving 100% Artemia nauplii. The second trial assessed the replacement of on-grown Artemia with proportions of formulated diet and Greenshell mussel that differed from those used in trial 1. Phyllosomata fed a 75% combination of formulated diet and 25% on-grown Artemia and 50% on-grown Artemia and 50% Greenshell mussel consistently showed the highest survival (>75%). Combinations of Greenshell mussel and formulated diet resulted in significantly (P < 0.05) reduced survival. In trial 3, phyllosomata were conditioned for 14, 18 or 21 days on Artemia nauplii prior to weaning onto a 100% formulated diet, which resulted in survival rates that were negatively related to the duration of feeding Artemia nauplii. In the final trial, phyllosomata were conditioned for 14 days on live on-grown Artemia prior to weaning onto one of three formulated diets (one diet with 44% CP and two diets with 50%). Phyllosomata fed a 44% CP diet consistently showed the highest survival (>35%) among all treatments, while those fed a 50%-squid CP diet showed a significant (P < 0.05) increase in mortality at day 24. The results of these trials demonstrate that hatcheries can potentially replace 75% of live on-grown Artemia with a formulated diet 7 days after hatch. The poor performance associated with feeding combinations of Greenshell mussel and formulated diet, and 100% formulated diet as well as conditioning phyllosomata for 14–21 days on live feeds prior to weaning onto a formulated diet highlights the importance of providing Artemia to stimulate feeding.