Induced spawning of maturing milkfish (Chanos chanos Forsskal) with gonadotropin-releasing hormone (GnRH) analogues administered in various ways

The response of mature female captive milkfish to mammalian and salmon gonadotropin-releasing hormone analogues (mGnRH-A and sGnRH-A) was investigated. Prior to spawning, six groups of three females received (1) 10–16 μg mGnRH-A from an osmotic pump implanted intraperitoneally (IP); (2) 100 μg mGnRH-A from a cholesterol/cellulose pellet implanted IP; (3) 10 μg/kg mGnRH-A as an intramuscular (IM) injection; (4) 10–16 μg sGnRH-A from an osmotic pump implanted IP; (5) 100 μg sGnRH-A from a cholesterol/cellulose pellet implanted IP, and (6) a cholesterol/cellulose pellet without analogue implanted IP.

The most effective treatment was 100 μg sGnRH-A/fish given in a cholesterol/cellulose pellet; all (3/3) of the fish spawned. However, mGnRH-A was more effective (2/3) compared with sGnRH-A (1/3) if osmotic pumps were used to administer GnRH-A. If the dose and method of administration were not considered, then the salmon and mammalian GnRH analogues were equally effective (62–67%) for induction of ovulation and natural spawning in milkfish. Gonads of control fish regressed.

At the doses tested, injections or pellet implantations were more effective compared with osmotic pumps. All pellet-implanted and injected females responded to treatment and 75% (6/8) spawned; half (3/6) of the pump-implanted females spawned. Spawning occurred from 18 to 36 h after treatment.     

Physiological responses, desaturase activity, and fatty acid composition in milkfish (Chanos chanos) under cold acclimation

Physiological responses of milkfish (Chanos chanos) under cold shock and acclimation were investigated. The experimental milkfish, a warm-water teleost, were initially acclimated at 25 °C and then transferred directly to 15 °C; stress responses of this species were monitored for 1 week. Parameters monitored included plasma glucose, lactate, and lipids, as well as stearoyl-CoA desaturase activity and fatty acid compositions of hepatic membranes. All parameters showed significant changes in the process of cold acclimation. A hyperglycemic response indicated by a notable and steady increase in plasma glucose levels from 85 mg dl⁻¹ to the highest level of 458.2 mg dl⁻¹ in 24 h was followed by a rapid decline thereafter. The elevation in plasma glucose content under cold shock resulted from gluconeogenesis and glycogenolysis, indicated by correlated changes in plasma glucose with fructose-1,6-biphosphatase and phosphorylase a activities. Plasma lactate concentrations remarkably increased from 47 mg dl⁻¹ on day 0 to 149.6 and 120.4 mg dl⁻¹ on days 1 and 2, respectively, and then rapidly declined to the same level as the control thereafter. In contrast, plasma lipids increased gradually from 44.8 mg dl⁻¹ to 191 mg dl⁻¹ over the 5-day acclimation period, followed by a declining trend from day 6 on. Furthermore, changes in monounsaturated fatty acids were highly correlated with those of stearoyl-CoA desaturase activities in hepatic microsomes of milkfish during cold acclimation. Results indicate that in milkfish subjected to cold stress, plasma hyperglycemic and hyperlactemic responses can be used as acute stress indicators, and plasma lipids can be used as a chronic stress indicator.     

Technical efficiency analysis of milkfish (Chanos chanos) production in Taiwan—an application of the stochastic frontier production function

Milkfish has been farmed in Taiwan for over 300 years. Faced with limited land resources, a labor shortage, decreasing demand, and growth of imported fisheries products, the industry is looking at the problem of how to maintain a sustainable and efficient production. This study specifies a stochastic production frontier function to estimate potential milkfish farm output and efficiency by using 1997–1999 data from a survey of 433 aquaculture milkfish farms. Both Translog and Cobb–Douglas frontier production models are estimated using the maximum likelihood estimation method. Empirical results show that the Translog stochastic production function model fits the data better and that milkfish farming in Taiwan exhibits diminishing returns to scale. We also compare estimated maximum potential milkfish production per hectare under various pond conditions to provide managers with information about how to boost efficiency. In addition, this study estimates substitution elasticities and complementarity of input factors for milkfish farms to provide helpful information for milkfish farmers on how to reallocate input resources and help raise milkfish productivity through improvements in technical efficiency.     

Effects of several factors on growth of milkfish (Chanos chanos Forskal) fingerlings reared with artificial diets in aquaria

This paper presents the effects of feeding level, feeding frequency, salinity of water, kind and particle size of diets, and stocking density on the growth of milkfish (Chanos chanos Forskal) fingerlings which were reared with artificial diets in laboratory tanks. Experimental groups were designed using orthogonal array L₈, and the results were evaluated statistically. Growth of the milkfish fingerlings varied markedly with the kind of diets used and feeding level. The feeding frequency and particle size of the diets also affected growth of the fingerlings significantly, but the salinity of the water did not. The weight gain of the fingerlings did not vary with the stocking densities significantly, whereas the increase (%) in body length was greater at a lower stocking density. The milkfish fingerlings showed the best growth in terms of both weight gain and increase in body length when reared on a purified diet containing 35% casein and 15% gelatin as protein sources under the following conditions: feeding level, 30–35% of body weight; feeding frequency, twice a day; particle size of diets, 125–250 μm diameter; and stocking density, $\text{5 fish}\text{5-liter}$ tank. The means and confidence limits of the weight gain (%) and increase (%) in body length of milkfish fingerlings under the best conditions adopted were estimated to be 360 ± 63.7 and 62.1 ± 10.6, respectively.     

Growth and survival of European sea bass (Dicentrarchus Labrax) larvae fed from first feeding on compound diets containing medium-chain triacylglycerols

A 21-day feeding trial was carried out to investigate the ability of first feeding European sea bass larvae to utilize medium-chain triacylglycerols as an alternative source of energy. Three compound diets based on soluble fish protein concentrate and yeast were supplemented with either 3% tricaproin (TC6), tricaprylin (TC8) or tricaprin (TC10). A diet containing triolein (TOL) was used as a reference diet. Diets were tested on four replicate groups of first feeding European sea bass larvae at 20°C, i.e. 6 days after hatching. At the end of the 21-day trial, TC8 yielded significantly higher survival (57±8% vs. 28±11% for the three other groups). Considered together, larvae fed TC8 and TC6 displayed better growth rates than larvae fed TOL and TC10 (final mean wet weights: 1.5±0.3 mg vs. 1.2±0.2 mg, respectively). The fatty acid composition of larval total lipid revealed a low deposit of medium-chain fatty acids (between 1 and 3% of total fatty acids) suggesting that medium-chain fatty acids were oxidized for energetic purposes. Tricaprylin and to a lesser extent tricaproin, appear to be potential energy sources for first feeding European sea bass larvae reared on compound diets.     

The effect of duration of feeding on survival,growth and production of milkfish, Chanos chanos (Forskal), in brackishwater ponds in The Philippines

Milkfish (Chanos chanos) fingerlings with an average weight of 16.3 g were stocked at 4000 per ha in twelve 500-m² experimental brackishwater ponds. The duration of supplementary feeding using pelletized chick starter (21.15% protein) at a ration of 5% of the biomass, was varied between 0 and 3 months. The duration of supplementary feeding had no significant effect on the survival, growth and production of milkfish. The results indicated that supplementary feeding of milkfish was not necessary at a stocking level of 4000 fish/ha, when adequate pond fertilization was carried out.     

Effect of dietary 22:6n-3 on growth,survival and tissue fatty acid profile of striped trumpeter (Latris lineata) larvae fed enriched Artemia

The effect of dietary 22:6n-3 (docosahexaenoic acid, DHA) on growth and survival was determined in striped trumpeter during metamorphosis and the Artemia-feeding period (16–36 days posthatch, dph). Artemia were enriched on one of five experimental emulsions that contained graduated concentrations of DHA and constant 20:4n-6 (arachidonic acid, ARA). We also compared larval performance using a commercial enrichment product high in n-3 PUFA. Final DHA concentrations in Artemia enriched on the experimental emulsions ranged from 0.1–20.8 mg/g DM, while Artemia fed the commercial product had 18.2 mg DHA/g DM. Each of the six diets was fed to larvae in four replicate 300-l tanks. Standard length (range 10.0–11.2 mm) and dry weight (range 1.6–2.5 mg) of larvae at the end of the experiment were directly related to dietary DHA, with the highest growth recorded in the experimental diet with the greatest concentration of DHA (20.8 mg/g DM). Survival at 36 dph was not influenced by dietary DHA and ranged from 20–44%. Mortality increased noticeably, regardless of dietary treatment, when larvae attained a standard length of approximately 9.5 mm. Mortality was related to a nocturnal behaviour where larvae would migrate to the tank bottom during the dark phase. Fatty acid profiles of the larvae were generally correlated to dietary fatty acids. Dietary DHA was found to be important in larval striped trumpeter growth, where enhanced growth probably shortened the critical period of metamorphosis and the window where nocturnal downward migration and mortality occurred.     

Effect of temperature on hatching success and size of striped trumpeter (Latris lineata) larvae

Egg samples were collected from captive striped trumpeter maintained under phase-shifted and simulated ambient photothermal regimes and incubated at 9, 10, 11, 12, 13, 14, 15 or 16 °C. No eggs hatched at 9 °C. Time to hatch decreased from 9.6 to 4.2 days as temperature increased from 10 to 16 °C. Survival to hatch was low at 10 and 11 °C, but similar within the range 12–16 °C. Larval length at hatching was greatest at 14 °C, with no significant difference in yolk volume or muscle depth at vent across the range of temperatures. The results of our study suggest that the optimal temperature for the incubation of striped trumpeter eggs is 14 °C, which is higher than found previously.     

The effect of phytates on the growth of rainbow trout (Salmo gairdneri) fed purified diets containing varying quantities of calcium and magnesium

Rainbow trout were fed for 150 days on four purified diets containing 0 and 0.5% phytic acid. These diets contained increasing increments of Ca (0.92–1.30%) and Mg (0.054–0.085%). The fish fed the diets containing phytic acid had 10% reduced growth and feed conversion. Increasing Ca and Mg content of the diet in the presence of phytic acid did not affect growth and feed conversion. Fish fed diets containing over 1% Ca without phytic acid had a 5% reduction in growth and feed conversion. The zinc and iron levels in the blood of the fish fed the diets containing phytic acid were not significantly different from the controls. The copper levels in the blood decreased in the fish diets with increasing increments of Ca ang Mg, but phytic acid did not influence this change. Increasing increments of Ca and Mg reduced the mean copper levels in the liver from 60 to 37 ppm. Similar reductions were found when phytic acid was included in the diet. Mean liver zinc levels did not significantly vary regardless of the diet fed. In vitro tests confirmed that phytic acid/protein (casein) complexes are only partially hydrolyzed by pepsin. In vivo tests with rainbow trout in which a casein/phytate complex was substituted for casein showed a 6.6% reduction in diet digestibility. It was concluded that the reduced growth in fish fed diets containing phytic acid was related to a reduction in protein availability rather than to an alteration in the bioavailability of Zn, Fe, or Cu.     

日本鳗鲡仔鱼的开口饵料和行为特征

在连续多年日本鳗鲡人工繁殖实验的基础上,研究了不同饵料对日本鳗鲡仔鱼存活率的影响,并记录了仔鱼的运动特征和摄食行为。结果显示,与对照组(不投饵)相比,投喂以鲨鱼卵、磷虾提取液为基础的饵料和以鲨鱼卵、海蜇匀浆液为基础的饵料以及微绿球藻液均提高了日本鳗鲡仔鱼的存活率,仔鱼发育至柳叶鳗前期阶段;而投喂以鲨鱼卵、卤虫匀浆液为基础的饵料和以卤虫匀浆液、磷虾提取液为基础的饵料,以及轮虫、海带+龙须菜匀浆液或海蜇以及发酵鲨鱼肉,均降低日本鳗鲡仔鱼的存活率。实验同时还研究了日本鳗鲡仔鱼的主动摄食行为,摄食时仔鱼先用吻端反复多次触碰食物,然后张开下颌咬食,证实了日本鳗鲡早期仔鱼的摄食方式是触碰后咬食。     

Effects on growth and survival of loach (Misgurnus anguillicaudatus) larvae when co-fed on live and microparticle diets

The effectiveness of co-feeding loach ( Misgurnus anguillicaudatus ) larvae with live and microparticle diets on weaning performance was described here. Dry weight, total length, length and weight-specific growth rate (SGR) and survivals were monitored at 23–25 °C from the 4th day post hatching (dph) in different diet regimes, which included: microparticle diets (A), live cladocerans (B), enriched cladocerans (C), half microparticle diets plus half live cladocerans (D) and half microparticle diets plus half enriched cladocerans (E). The SGR (L and W) were significantly lower in treatment A than in other treatments after completing metamorphosis (day 4–20, P <0.05). On 30 dph, dry weight (mg) and total length (mm) were significantly lower in treatment A than in other treatments ( P <0.05). There were no significant differences in growth in treatments B, C, D and E before 30 dph. However, when live feed was withdrawn from 31–60 dph, in metamorphosed fish, there were significant differences ( P <0.05) among the treatments in survival and growth. Metamorphosed fish in treatment E had higher survival than the fish in other treatments at the end of the experiment. The SGR (L and W) of weaned fish in treatments B and C were similar but lower than in treatments A, D and E respectively. However, dry weight and total length in treatment A were significantly lower than in treatments D and E. It is suggested that weaning of M. anguillicaudatus from early development would appear to be feasible and that larval co-feeding improves the growth and the survival.     

Growth, survival, lipid composition and pigmentation of turbot (Scophthalmus maximus) larvae fed live-prey enriched in Arachidonic and Eicosapentaenoic acids

Turbot larvae were fed live-prey enriched with different levels of arachidonic (ARA) and eicosapentaenoic (EPA) acids to study the effects of these fatty acids on body composition and pigmentation success. Significantly reduced pigmentation was obtained in those fish fed medium and high ARA diets for 43 days. Growth and survival were the same for all groups. The incorporation of ARA and EPA in fish eyes, brains, livers and carcasses reflected the percentage of these fatty acids in the diets. ARA accumulation was similar in all tissues, but brain accumulated EPA was less efficient than the other tissues examined. A highly significant, negative correlation was found between the %ARA in turbot juvenile brain total lipids and pigmentation success. A weaker, positive correlation was found between brain EPA and pigmentation. Increasing dietary ARA affected the fatty acid composition of turbot brain phosphoglycerides more than increasing dietary EPA, especially in phosphatidylinositol (PI) and phosphatidylethanolamine (PE). A negative relationship was found between percentage normal pigmentation and ARA levels in brain phosphatidylcholine (PC), PE and phosphatidylserine (PS). Elevated levels of ARA in PI also resulted in malpigmented juveniles, but EPA:ARA ratios ≥1 in PI were associated with normal pigmentation. We conclude that, given a sufficiency of dietary docosahexaenoic acid (DHA), the optimum dietary level of EPA is not a function of DHA, but of dietary ARA.     

牟氏角毛藻和海洋红酵母对玉足海参浮游幼体发育、生长及成活率的影响

为了考察海洋红酵母是否适合作为替代饵料用于玉足海参浮游幼体培育,实验利用牟氏角毛藻和海洋红酵母单独投喂和按照一定比例混合投喂,对玉足海参浮游幼体生长、发育以及成活率的影响进行研究.将牟氏角毛藻液与海洋红酵母稀释液分别按照4 ∶0、3∶ 1、2 ∶ 2、1∶3和0∶4的体积比混合后投喂玉足海参浮游幼体,依次标记为A、B、...     

Comparison of growth and survival of white shrimp postlarvae (Litopenaeus vannamei) fed dried Artemia biomass versus four commercial feeds and three crustacean meals

The use of dried Artemia biomass meal as an exclusive feed for postlarval white shrimp (Litopenaeus vannamei) was compared with four commercial feeds and three crustacean meals in a series of trials. Postlarvae (PL1–PL6) were stocked at a density of 1.5–2.5/litres in 16 tanks (100 litres volume) and fed, ad libidum, five times a day, over 23–29 days. Feeding postlarval shrimp with dried Artemia biomass resulted in a significantly larger size than feeding with three of the commercial feeds, and the crustacean meals. There was no significant size difference observed in animals fed with Artemia biomass and the commercial 'Golden Pearls' feed for postlarvae, however the coefficient of variation among the size of the 'Golden Pearls' fed animals was significantly higher. The weight increase of animals fed with Artemia biomass was higher than in animals fed with all the tested feeds. The survival rate was not significantly different in animals fed with Artemia flakes from 'Salt Creek', 'Bio-Marine', 'Golden Pearls' and Artemia biomass, however the survival rate was significantly larger in animals fed with Artemia biomass than in animals fed with the crustacean meals and 'Artemac.' Results suggest that dried Artemia biomass is a well-suited feed for postlarval L. vannamei.     

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.     

A study of appetite, digestion and growth in juvenile green turtle (Chelonia mydas L.) fed on artificial diets

One-year-old immature green turtles (500–900 g) were kept at 25°C in recirculating seawater. When deprived of food for 108 h and then offered floating trout pellets, they consumed a satiation meal (S g) described by the equation S = 0.025 W^0.96 where W is wet body weight in g. When food was offered at different deprivation times after satiation, maximum meals were taken after 60–72 h and corresponded to 2.5% body weight. Longer deprivation (108 h) led to reduced intake of 1.9–2% body weight. Gastric emptying was measured using X-radiography or chromic oxide to label the faeces. Complete stomach emptying required 110 ± 11 h S.D. and maximum appetite occurred when the stomach was estimated to be 80–95% empty. The average time for a meal to be voided from the alimentary tract was 176 ± 16 h S.D. Diets containing 40–50% protein and 4.2–5 kcal/gram were assimilated with apparent efficiencies of 76 ± 6% S.D. and 86 ± 6% for energy and protein nitrogen, respectively. A preliminary estimate for an energy budget for these animals based on a 23 day growth period accounted for 90% of the daily food intake as:

100 I39M + 32E

where known daily intake (I calories) is compared with measures or estimates of metabolic rate (M), growth (G) and excreted wastes (E). Although this balance is similar to that of herbivorous fish, the turtle has slower feeding and digestion rates than its teleost counterparts.     

高脂日粮添加胆汁酸对大口黑鲈生长性能、脂代谢和胆汁酸代谢的调节作用

为探究胆汁酸对高脂饲料饲喂下大口黑鲈(Micropterus salmoides)生长生理、脂代谢和胆汁酸代谢的影响, 配制基础饲料(脂肪含量 10.6%, 对照组 C)、高脂饲料(脂肪含量 17.5%, 高脂组 HF)、高脂饲料+300 mg/kg 胆汁酸 (HFB1)、高脂饲料+600 mg/kg 胆汁酸(HFB2)、高脂饲料+900 mg/kg 胆汁酸(HFB3) 5 种试验饲料。将 750 尾大口黑鲈随机分为 5 组, 每个组设置 3 个平行缸, 每缸 50 尾, 进行 7 周养殖实验。结果表明: 高脂饲料显著降低大口黑鲈生长性能, 而添加胆汁酸后可改善高脂饲料对大口黑鲈生长的不利影响。饲喂高脂饲料组血浆和肝脏中甘油三酯 (TG)含量显著升高(P＜0.05)。添加胆汁酸后, 肝脏中 TG 含量显著降低(P＜0.05), 而血浆中 TG 含量在胆汁酸添加量为 900 mg/kg 时显著下降(P＜0.05)。肝脏和血浆中总胆酸(TBA)含量随着胆汁酸添加量的升高而显著增加(P＜0.05)。 胆汁酸添加量为 600 mg/kg 时, 肝脏中法尼醇 X 受体基因(fxr)表达量上调(P＜0.05), 胆汁酸合成和转运相关基因 (cyp7a1、bsep、asbt)均显著上调(P＜0.05)。同时对脂代谢相关基因表达进行检测, 发现 fxr 诱导 shp 的表达, 抑制肝脏中 srebp1 及脂肪合成相关基因(fas、acc2)的表达。此外, 胆汁酸增加肝脏中脂肪分解和 β 氧化相关基因(lpl、 hl、hsl、cpt1、acox1)的表达水平。综上所述, 高脂饲料中添加胆汁酸可改善大口黑鲈生长性能, 通过 FXR/SHP/ SREBP1 信号通路调节脂质代谢, 并促进胆汁酸合成和循环, 本研究为进一步研究胆汁酸在鱼类中的营养调控作用奠定了基础。     

Phosphorus utilization in rainbow trout (Oncorhynchus mykiss) fed practical diets and its consequences on effluent phosphorus levels

Excessive dietary phosphorous (P) concentrations in effluents from aquaculture present a major environmental problem. We therefore studied the effect of dietary P and vitamin D₃ on P utilization by rainbow trout-fed practical diets and on P concentrations in the soluble, particulate and settleable components of the effluent from fish tanks. Rainbow trout (average weight: 78 g, initial biomass: 13 kg in 0.7 m³ tanks) were fed for 11 weeks, practical diets that varied in total P, available P, and vitamin D₃ concentrations. Soluble, particulate (10–200 μm) and settleable (>200 μm) P in the effluent were sampled every 0.5–6 h for 1–3 days in the third and eleventh weeks of the experiment. Trout in all diets more than doubled their weight after 11 weeks. Increasing the concentrations of available dietary P from 0.24% to 0.88% modestly enhanced growth rate. Feed conversion ratio (FCR) and biomass gain per gram P consumed decreased as dietary P concentrations increased. Carcass P, daily P gain, and plasma P concentrations were lower in fish fed with low P diets. Soluble P concentrations in the effluent peaked immediately after and again 4–6 h after feeding, and is a linear function of available dietary P. No soluble P would be produced during consumption of diets containing less than 0.22±0.02% available P. Above this dietary concentration, soluble P would be excreted at 6.9±0.4 mg/day/kg for each 0.1% increase in available dietary P. Particulate P concentrations in the effluent were independent of dietary P concentrations. Settleable, presumably fecal, P concentrations tended to increase with dietary P concentrations. In trout fed with low P (0.24% available P, 0.6% total P) diets, 60% of total dietary P were retained by the fish and the remaining 40% were excreted in the effluent as settleable P (20–30%) and particulate or soluble P (10–20%). In trout fed with high P (0.59–0.88% available P; 0.9–1.2% total P) diets, 30–55% of total dietary P was retained by fish, and the remaining 15–25% appeared in the effluent as settleable P, 20–55% as soluble P, and 5–10% as particulate P. Vitamin D₃ did not affect fish growth nor effluent P levels. Physicochemical management of aquaculture effluents should consider the effect of diets on partitioning of effluent P, the peaks of soluble P concentration following feeding, and the contributions of particulate P to total P in the effluent. Increasing our understanding of how dietary P is utilized and is subsequently partitioned in the effluent can contribute significantly towards alleviating this important environmental and industry problem.     

Effects of two commercial microdiets on growth and survival of barramundi (Lates calcarifer Bloch) larvae within various early weaning protocols

Because of high costs and labour requirements along with the highly variable nutritional value of live feeds, we investigated the possibility of early weaning for barramundi (Lates calcarifer Bloch) larvae aimed at reducing the use of Artemia. Two commercial microdiets, Gemma Micro (Skretting, Australia) and Proton (INVE, Belgium) were compared for growth and survival of larvae using three weaning protocols, until 33 days posthatch (dph). Enriched rotifers were fed to larvae in all protocols through mouth opening until 21, 18 and 30 dph (protocols 1, 2 and 3, respectively). At 13 dph, enriched Artemia metanauplii were introduced to weaning protocols 1 and 2, and continued until 29 and 24 dph, respectively, whereas protocol 3 did not receive Artemia. Microdiet was initiated at 20, 16 and 13 dph in protocols 1, 2 and 3, respectively. Barramundi larvae grew successfully to 33 dph when co‐fed rotifers and microdiet, and significantly larger larvae resulted from feeding Gemma Micro rather than Proton, when Artemia were not used. However, larvae weaned onto Proton using a longer period of Artemia provision were significantly larger than larvae reared according to all other protocols. Survival was significantly higher in all Gemma Micro protocols when compared with Proton protocols. This was in part due to higher cannibalism when using Proton compared with Gemma Micro (22.8 ± 0.9% and 9.2 ± 0.6%, respectively). Cannibalism became more noticeable in all protocols when the larvae reached 7–8 mm standard length and further increased after the cessation of live feed. Tank biomass production was the highest when larvae were weaned onto Gemma Micro including a short period of Artemia provision as a result of a combination of high growth and survival. However, similar biomass production resulted when larvae were weaned directly from rotifers onto Gemma Micro and/or from a prolonged Artemia period onto proton. The success of weaning barramundi larvae directly to microdiet from rotifers, thus eliminating the need for Artemia, was influenced by the microdiet. Relatively higher levels of free amino acids and lipids were believed to contribute to increasing larval growth and survival. Larvae that were fed Gemma Micro showed higher growth when Artemia were utilized for a shorter period, while Proton‐fed larvae benefited from an extended Artemia feeding period.