Growth,food intake,protein retention and fatty acid profile in Octopus vulgaris (Cuvier, 1797) fed agglutinated moist diets containing fresh and dry raw materials based on aquaculture by‐products

The lack of specific compound diets for cephalopods is limiting the industrial development of some species. In this study, four agglutinated moist diets were tested in individually reared Octopus vulgaris (979 ± 151 g) for 8 weeks. All diets were based on bogue Boops boops, accidentally reared in fish farms (aquaculture by‐product), and agglutinated with alginate and calcium. One diet was based exclusively on bogue fillets, two on bogue fillets complemented with meat from two crab species (Portunus pelagicus, Grapsus grapsus) and the last one on bogue and G. grapsus meals. As a control diet, bogue and P. pelagicus were supplied fresh on alternate days. All diets induced similar feed intake (2.1–2.6% day^?1). However, the meal‐based diet induced negative growth in comparison with the control and the other agglutinated diets (0.80–0.85% day^?1). Higher lipid content in agglutinated diets (28–30% dw) in comparison with the control diet (16% dw) led to higher protein retention in muscle. These results underline the inadequacy of traditional meals in diets for cephalopods and that the inclusion of crab meat did not increase feeding rates and growth in O. vulgaris. The dietary fatty acid, with high levels of oleic and linoleic acid and low levels of ARA, clearly reflected in digestive gland, while only decreasing ARA and increasing EPA levels were observed in muscle, with no apparent negative effect on growth.     

Biological performance of Octopus vulgaris in ‘integrated aquaculture’ models: effect of two potential fresh diets,sex and sexual maturation during the grow‐out phase

Two fresh diets were tested on the biological performance of males and females of Octopus vulgaris under industrial rearing conditions in floating cages. The presence of females could potentially release paralarvae to the natural environment (‘integrated aquaculture’). Octopuses were fed on a single diet of bogue (aquaculture by‐product), and on a mixed diet (60–40% crab‐bogue), in two trials. In Trial 1 (918 ± 125 g), growth was higher in octopuses fed on the mixed diet (1.9–2.0%d^?1) than in those fed on the bogue diet (1.8–1.9%d^?1) irrespective of sex, and mortality was 3% regardless of sex and diet. In Trial 2 (1483 ± 269 g), growth was higher in males fed on the mixed diet (1.8%d^?1) than in males fed on the bogue diet (1.4%d^?1), both higher than females (1.1–1.3%d^?1), and mortality was 22–28% regardless of sex and diet. Best biological performance in trial 1 was related to the lack of functional maturation in females, evidence by the low average gonadosomatic index (2.0–3.6%) in comparison with trial 2 (8.8–11.4%), regardless of diet. No correlations between final weight and sexual maturity indices were found, so the length of the rearing period to maximize biomass increment or to release paralarvae depends on functional maturation in females.     

Effect of two extruded diets with different fish and squid meal ratio on growth,digestibility and body composition of Octopus vulgaris (Cuvier, 1797)

The present work studies the growth and body composition of 18 Octopus vulgaris (6 per treatment) fed two extruded diets, namely FMS and 3FMS, based on different fish and squid meal ratios (1:1, and 3:1 respectively). The diets are compared with a control diet based on crab (Carcinus mediterraneus) and bogue (Boops boops). The growing tests were conducted on animals placed in individual 300 L rectangular fibreglass tanks in an open seawater system, containing PVC tubes as shelters, resulting in 100% survival rate. The control group exhibited the highest specific growth rates (SGR = 2.14%BW day^?1), while values of around 0.69%BW day^?1 were achieved by octopuses fed the extruded diets. Even though the three groups of animals showed similar digestive gland indexes, the two extruded diets promoted significant differences in the muscle composition and fatness of the digestive gland. Digestibility of dry matter was not affected by the type of extruded diet, obtaining ADC values of around 88%. The results suggest that squid and fish meal can be both used in dry pelleted extruded diets, with moderate acceptance by the octopus, even though the formulation must be optimized with the aim of improving acceptability and achieve growths in the range of natural diets.     

Effects of supplementation of decapod zoea to Artemia basal diet on fatty acid composition and digestive gland histology in common octopus (Octopus vulgaris) paralarvae

The present study aimed to evaluate the effect of the supplementation of different crab zoeas to enriched Artemia basal diet for Octopus vulgaris paralarvae during the first month of life. Paralarvae were fed using enriched Artemia nauplii alone and Artemia co‐fed either first zoea stages of Grapsus adscensionis or Plagusia depressa. The experiment was carried out over a period of 28 days, in 0.12 m³ tanks with a flow‐through rearing system. Growth in dry weight as well as mantle length and width were assessed weekly. Additionally, prey and paralarvae fatty acid composition and digestive gland (DG) histology were evaluated. Addition of low amounts of crab zoeas (approx. 100 indv. L^?1 day^?1) provided during critical life stages of O. vulgaris proved to be good enough to improve paralarvae growth and survival in comparison with those fed exclusively on enriched Artemia. These results were supported by the finding of a higher number of glycoprotein absorption vacuoles in the DG from paralarvae co‐fed crab zoeas, suggesting a higher feeding activity. In addition, fatty acid analysis of crab zoea showed that these are good sources of dietary arachidonic and eicosapentaenoic acids during the octopus planktonic life stage, whereas the low docosahexaenoic (DHA) content suggests the use of additional DHA sources or higher zoea densities to meet paralarvae nutritional demand to carry out a successful metamorphosis to benthic life.     

Efficient utilization of dietary lipids in Octopus vulgaris (Cuvier 1797) fed fresh and agglutinated moist diets based on aquaculture by‐products and low price trash species

The aim of this study was to evaluate growth, biochemical composition and dietary nutrients utilization in Octopus vulgaris fed on four diets based on bogue Boops boops, from different origin and in two presentations: fresh discarded bogue (aquaculture by‐product) (DB‐f), fresh wild bogue (low price trash species) (WB‐f), discarded bogue agglutinated moist diet (DB‐m) and wild bogue agglutinated moist diet (WB‐m). Diets based on DB showed higher lipid content (19–26% dw) than those based on WB (5–6% dw). Octopuses fed on DB‐based diets showed higher growth (1.5–1.9% day^?1) and higher protein efficiency ratio (0.64–0.69) than those fed on WB‐based diet (1.1–1.5% day^?1 and 0.36–0.37 respectively), which suggests good utilization of dietary lipids and also a possible protein sparing effect by lipids in O. vulgaris. Octopuses fed on diets presented fresh showed a higher growth (1.9–1.5% day^?1) and a higher feed efficiency (62–65%) than those fed on agglutinated diets (1.1–1.5% and 52–60% day^?1 respectively). Regarding fatty acids, the digestive gland clearly reflected dietary lipid and fatty acid profile, while muscle showed a more stable composition. Low dietary ARA content reflected in octopus tissues, especially in specimens fed on DB‐based diets, which did not seem to affect growth during the experimental period.     

Effective use of glucose rather than starch in formulated semimoist diets of common octopus (Octopus vulgaris)

The aim of the present work was to test the capacity of Octopus vulgaris to use carbohydrates supplied in three diets: a diet without added carbohydrates (diet C0: 500 g kg^?1 water, 200 g kg^?1 gelatine, 100 g kg^?1 egg yolk powder, 50 g kg^?1 freeze‐dried Sardinella aurita and 150 g kg^?1 freeze‐dried Todarodes sagittatus) and two obtained by substituting 50 g kg^?1 of T. sagittatus by glucose (diet GLU50) or by starch (diet STA50). The most stable and best‐accepted diet was STA50 (SFR 1.26%BW day^?1) although there were no significant differences in the growth rates obtained with the three diets: 10.12 g day^?1, 9.37 g day^?1 and 11.22 g day^?1 for C0, GLU50 and STA50, respectively (P > 0.05). The feed efficiency indices were better for GLU50, of particular note being the protein productive value of 71.88% and a feed conversion ratio lower than 1. Protein and lipid digestibility were similar in all the three diets (96–98% for proteins and 85–94% for lipids), whereas carbohydrate digestibility was higher in GLU50 (98%) than in C0 (84%) and STA50 (0.33%). The content of carbohydrates increased in muscle and the digestive gland as a consequence of the increased carbohydrates intake.     

Effective use of glucose rather than starch in formulated semimoist diets of common octopus (Octopus vulgaris)

The aim of the present work was to test the capacity of O. vulgaris to use carbohydrates supplied in three diets: a diet without added carbohydrates (diet C0: 500 g kg^?1 water, 200 g kg^?1 gelatine, 100 g kg^?1 egg yolk powder, 50 g kg^?1 freeze‐dried Sardinella aurita and 150 g kg^?1 freeze‐dried Todarodes sagittatus), and two obtained by substituting 50 g kg^?1 of T. sagittatus by glucose (diet GLU50) or by starch (diet STA50). The most stable and best accepted diet was STA50 (SFR 1.26%BW day^?1), although there were no significant differences in the growth rates obtained with the three diets: 10.1 g day^?1, 9.4 g day^?1 and 11.2 g day^?1 for C0, GLU50 and STA50, respectively (P > 0.05). The feed efficiency indices were better for GLU50, of particular note being the protein productive value of 72% and a feed conversion ratio lower than 1. Protein and lipid digestibility were similar in all three diets (96–98% for proteins and 85–94% for lipids), whereas carbohydrate digestibility was higher in GLU50 (98%) than in C0 (84%) and STA50 (0.33%). The content of carbohydrates increased in muscle and the digestive gland as a consequence of the increased carbohydrates intake.     

Performance of formulated diets with different level of lipids and glutamate supplementation in Octopus vulgaris

Growth, feed efficiency and proximate and lipid class composition of subadults Octopus vulgaris (788 ± 133 g; 18.5°C) fed formulated diets of low lipid (LL: 8 g kg^?1) and high lipid levels (HL: 84 g kg^?1) and each one of these with three different levels of glutamate supplementation (0, 5 and 20 g kg^?1) were compared. All the animals accepted the diets with a survival of 100%. The addition of glutamate did not stimulate feeding rates in any of the assays (2.48–2.64 and 1.86–2.01%Body weight day^?1 for LL and HL, respectively; P > 0.05). The best growth, feed efficiency and protein productive value were observed in the groups fed 5 or 20 g kg^?1 glutamate supplementation at both lipid levels, with significant differences for LL diet (P < 0.05). A better feed efficiency was achieved with the HL diet (14.6–27.5% vs. 2.5–19.2% for LL diet). There were no significant differences in the proximate composition of carcass (animal excluding the digestive gland). However, a substantial amount of lipids accumulated in the digestive gland, mainly triglycerides, was detected as a consequence of higher lipid ingestion or glutamate supplementation. It was notable the lower percentages of phosphatidylethanolamine and phosphatidylcholine in the digestive gland of animals with best growth.     

High feeding and growth rates in common octopus (Octopus vulgaris) fed formulated feeds with an improved amino acid profile and mixture of binders

Four semi‐moist formulated feeds were supplied to Octopus vulgaris subadults (664 ± 70 g; 18.4 ± 0.7°C) in two different experiments. In the experiment #1, two diets were prepared with a new mixture of binders (gelatine 150 g kg^?1, starch 100 g kg^?1 and gum 50 g kg^?1). The GEL15‐Squid and GEL15‐Hake feeds included 100 g kg^?1 freeze‐dried squid (Todarodes sagittatus) or hake (Merluccius sp.) respectively. Both feeds showed low water disintegration rates at 24 h (13.6–15.0% dry weight). The specific feeding rate was higher in animals fed GEL15‐Hake (2.7%BW day^?1), but the growth and feed efficiency were significantly better in animals fed GEL15‐Squid (1.4%BW day^?1 and 61.2% respectively; P < 0.05). The proximate composition of the digestive gland, carcass and whole animals was similar. In the experiment #2, the GEL15‐Squid amino acid profile was improved by replacing 50 g kg^?1 gelatine by 50 g kg^?1 freeze‐dried squid (GEL10‐Squid) or freeze‐dried fish (GEL10‐Fish). These feeds showed higher water disintegration rates (31.7–36.3% dry weight). The feeding rates (2.2–2.3%BW day^?1), growth (1.5%BW day^?1) and feed efficiency were similar for both diets. Total lipids were higher in the digestive gland and whole animals fed GEL10‐Fish diet (P < 0.05). Future effort could be directed towards alternative binders that allow improve amino acid balance with a minimum gelatine content or even supplementation trials including essential amino acids.     

Citric acid substituted the inclusion of inorganic phosphorus in diet of rainbow trout (Oncorhynchus mykiss)

This study was conducted to evaluate the effects of citric acid (CA) supplementation in diet without inorganic phosphorus (P) on growth, muscle and bone composition, proteolytic activities and serum antioxidant property of rainbow trout. Six diets were designed as the negative diet without monocalcium phosphate (MCP) supplementation, the positive diet containing 10 g kg^?1 MCP and CA supplementation diets with 4, 8, 12, 16 g kg^?1 CA supplementation in negative diet, and then were fed to rainbow trout (113.6 g) for 60 days. Results showed that the fish fed 8 g kg^?1 CA, 12 g kg^?1 CA diet had higher weight gain, higher contents of crude ash and P in bone, and lower feed conversion ratio than those of fish fed negative diet (P < 0.05), and showed the similar levels as those of fish fed positive diet (P > 0.05). The proximate composition and P level of muscle were not affected by dietary CA and MCP. The proteolytic activity in intestine, but not in stomach and gastric digesta, was significantly improved by dietary CA and MCP (P < 0.05), when compared with negative control. The activities of serum superoxide dismutase of 12 g kg^?1 CA and 10 g kg^?1 MCP groups were significantly higher, and the malondialdehyde of 8 g kg^?1 CA and 12 CA g kg^?1 groups were significantly lower than those of negative control (P < 0.05). The above results indicated that the supplementation of CA could substitute the inclusion of MCP in rainbow trout diet and the supplementation level was suggested to be 8–12 g kg^?1.     

Changes in lipid composition of different tissues of common octopus (Octopus vulgaris) during short‐term starvation

In this work, we study the variations in concentration (mg 100 g^?1 dry weight) and total content (mg individual^?1) of different lipid classes in muscle and the digestive gland of Octopus vulgaris during an 8‐day starvation period. In all the samples analysed, polar lipids (PL) predominated in muscle (267.3–337.2 mg 100 g^?1) compared with neutral lipids (66.9–104.7 mg 100 g^?1). A significant positive tendency was observed in muscle for the content and concentration of monoglycerides as a consequence of starvation (P < 0.05). Furthermore, a higher cholesterol (CHO) content was detected in this tissue after the fourth day of starvation compared with the fed animals (P < 0.05). Neutral lipids predominated in the digestive gland (12 958–14 151 mg 100 g^?1) compared with PL (3157–6517 mg 100 g^?1), with triglycerides, free fatty acids and monoglycerides being the major lipid classes. The concentration of PL and monoglycerides showed a positive trend with starvation, while the triacylglycerol showed a negative tendency (P < 0.05). The results suggest that triglycerides and CHO are transported simultaneously from the digestive gland to the muscular tissues during starvation and the preferential use of PL and CHO during growth phases. It was estimated that lipids contributed 26% of the energy costs of the animals during starvation, mainly in the form of triglycerides from the digestive gland.     

Dietary arginine requirement of juvenile swimming crab,Portunus trituberculatus

An 8‐week feeding trial was conducted to determine the optimal dietary arginine requirement for juvenile swimming crab Portunus trituberculatus. Six isonitrogenous and isolipidic experimental diets were formulated to contain graded arginine levels which ranged from 15.9 to 33.0 g kg^?1. Each diet was randomly assigned to triplicate groups of 60 juvenile swimming crabs (4.72 ± 0.12 g). The results indicated that dietary arginine had significant effects on weight gain (WG), specific growth rate (SGR), protein productive value, feed efficiency and protein efficiency ratio. Weight gain and SGR significantly increased with the dietary arginine increasing from 15.9 to 27.4 g kg^?1, while with the further increasing from 27.4 to 33.0 g kg^?1, WG and SGR did not increase significantly. Maximum arginine, proline and total essential amino acid contents in muscle were observed in 27.4 g kg^?1 group diet. The swimming crab fed the diet with lower dietary arginine level showed higher AST and lower ALT in the serum. Crab fed with the lower dietary arginine level had significantly lower ALT in the serum than the other groups. Haemolymph indexes were significantly affected by the dietary arginine level except for the cholesterol concentration, and the highest values were all found in 27.4 g kg^?1 group diet. The two slope broken‐line model using SGR showed that the optimal dietary arginine requirement was 27.7 g kg^?1 of the dry matter (56.0 g kg^?1 dietary protein) for juvenile swimming crab.     

Effects of dietary folic acid on growth,antioxidant capacity,non‐specific immune response and disease resistance of juvenile Chinese mitten crab Eriocheir sinensis (Milne‐Edwards, 1853)

An 8‐week study was conducted to determine folic acid requirement and its effect on antioxidant capacity and immunity in juvenile Chinese mitten crab Eriocheir sinensis (Milne‐Edwards, 1853), followed by a challenge assay with the pathogen Aeromonas hydrophila for 2 weeks. Folic acid was added to a basal diet at seven levels (0, 0.5, 1.0, 2.0, 4.0, 8.0, 16.0 mg folic acid kg^?1 diet), and a diet free of folic acid and vitamin B₁₂ was also included as a control. Crabs were fed twice daily in 32 tanks with 7.76–8.17 mg oxygen L^?1, 25.0–31.0 °C and 7.5–8.3 pH. Growth and feed efficiency were significantly greater in crabs fed ≥2.0 mg folic acid kg^?1, but not significantly different between crabs fed diets >2.0 mg folic acid. The superoxide dismutase activity and glutathione S‐transferase activity were highest in crabs fed ≥2.0 mg folic acid kg^?1, followed by those fed 0.5 and 1.0 mg folic acid kg^?1, and the control diet. The malondialdehyde content was highest in crabs fed the control diet, followed by those fed 0 mg folic acid kg^?1, and the lowest value occurred in those fed ≥0.5 mg folic acid kg^?1. Phenoloxidase activity and total haemocytes were significantly higher in crabs fed ≥2.0 mg folic acid kg^?1 than other diets. Crabs fed 2.0 mg folic acid kg^?1 had the highest lysozyme, acid phosphatase and alkaline phosphatase activities but the lowest cumulative mortality. The optimum dietary folic acid requirement by E. sinensis was estimated at 2.29–2.90 mg kg^?1 diet.     

Development of low‐lipid formulated feeds with different protein/energy ratios for Octopus vulgaris ongrowing

We studied the feeding and growth rates, feed efficiency and nutritional composition of subadult octopuses (689 ± 77 g) fed low‐lipid diets with two different protein/energy ratios (P/E): Medium P/E diet (30.5 g protein MJ^?1, 662 g kg^?1 protein dry weight (dw)) or High P/E diet (36.8 g protein MJ^?1, 843 g kg^?1 protein dw). Survival was 100% for the Medium P/E and 87.5% for the High P/E diet. The specific feeding rates were 1.91% and 1.67% body weight day^?1 for the Medium P/E and High P/E diet, respectively (P < 0.05). The specific growth rates (0.92% and 1.25% body weight day^?1), feed efficiency indices (47.3% and 72.7%), productive protein value (23.9% and 29.1%) and digestive gland index (5.6% and 6.4%) were significantly better in animals fed the High P/E than the Medium P/E diet (P < 0.05). The proximate composition of the digestive gland was similar for both diets, but the total lipid content of carcass was higher in animals fed the Medium P/E diet (P < 0.05). Our results suggest that the protein content of the feed could be a factor regulating feeding rates in octopus.     

Effect of arachidonic acid supplementation on reproductive performance of tank‐domesticated Penaeus monodon

The reproductive performance of domesticated Penaeus monodon was assessed when fed on two experimental semi‐moist maturation diets varying in their arachidonic acid content for 21 days before ablation and throughout a 17‐day reproductive assessment. The biochemical composition of the two semi‐moist two diets was similar with the exception of arachidonic acid (ARA) content; the basal diet (BAS) consisting of 0.9 g kg^?1 DM ARA (1.1% of total fatty acids) and the supplemented diet (ARA‐SUP) consisting of 5.0 g kg^?1 DM ARA (5.8% of total fatty acids). ARA/EPA and ARA/DPA ratios were 0.1 in the BAS diet and 0.5 in the ARA‐SUP diet. Fatty acid composition of the spawned eggs was comparable between diets with the exception of ARA concentration, which was higher in the ARA‐SUP (8.95 ± 0.44 g kg^?1 DM) than the BAS (3.23 ± 0.17 g kg^?1 DM) (P < 0.0001). The cumulative percentage of females spawning (mean ± SE after 17 days) (31.9 ± 7.0%; 24.1 ± 1.3%), number of spawnings per female (0.48 ± 0.1; 0.29 ± 0.02), and eggs per female (62 520 ± 16 935; 44 521 ± 9914) was significantly (P < 0.0001) higher for the ARA‐SUP than the BAS. Results of this study suggest that arachidonic acid plays a key role in promoting egg development and spawning in P. monodon.     

Digestive gland structure as a feed index for juveniles of the queen conch,Strombus gigas,reared with formulated food

One of the bottlenecks for the queen conch, Strombus gigas, aquaculture is the lack of well‐adapted formulated food for optimal growth. The goals of this study were to analyse the digestive gland structure of conchs fed with different diets using histochemical techniques and to evaluate the growth and survival of S. gigas juveniles with nine formulated diets (protein from 190 to 380 g kg^?1 and lipids from 26 to 82 g kg^?1). Proteoglycan granules and acidophilic granules were detected in the digestive cells. The abundance of both granule types was variable, according to the nutritional state of the animals. The granular content of the digestive cells of conchs fed with artificial diets was scarce when compared with conchs fed on natural food. Of the nine formulated feeds, the diet with 365 and 45 g kg^?1 of protein and lipids, respectively, gave the best growth in weight (0.20 g day^?1) and was also associated with digestive cells in the best condition as determined histologically. Histochemical analysis of the digestive gland differentiated with Alcian blue staining determines the nutritional status much better than a simple growth index and is therefore more useful in assessing adjustments to the feed formulation to meet the real needs of conchs.     

Utilization of diets with different fish oil content in common octopus (Octopus vulgaris Cuvier, 1797) and resulting changes in its biochemical composition

The aim of the present work was to obtain the lipid utilization of Octopus vulgaris supplying formulated semi‐moist diets with different contents in cod oil (reduced from water content): 0 g kg^?1 (A0, 138 g kg^?1 lipids DW; N = 4), 100 g kg^?1 (A100, 286 g kg^?1 lipids DW; N = 6) and 200 g kg^?1 (A200, 388 g kg^?1 lipids DW; N = 6). The rest of the ingredients were constant in the three diets: 200 g kg^?1 gelatin, 100 g kg^?1 egg yolk powder, 150 g kg^?1 freeze‐dried Todarodes sagittatus and 50 g kg^?1 freeze‐dried Sardinella aurita). Survival was 100% with the three diets. The highest absolute feeding (15.8 ± 1.2 g day^?1), growth (9.6 ± 1.4 g day^?1; 0.91% BW day^?1) and feed efficiency rates (60.3%) were obtained with diet A0. This diet also showed greater retention of lipid and protein than A100 and A200. Protein digestibility was above 95% in all of the diets. Only diet A0 led to a high lipid digestibility coefficient (81.25%), which fell drastically to 12.3% in A200. It was notable the high polar lipid digestibility rates (83–89%) respect to neutral lipids (2–87%) in all diets. The best results were obtained with lipid feeding rates of around 1 g day^?1 and a suitable lipid content on 130–140 g kg^?1 DW in formulated diets for O. vulgaris.     

Total aromatic amino acid requirement of juvenile grass carp (Ctenopharyngodon idella)

This experiment was conducted to investigate total aromatic amino acid requirement of juvenile grass carp Ctenopharyngodon idella. Six isonitrogenous and isoenergetic semipurified diets containing casein and gelatin with graded level of phenylalanine (7.8, 11.1, 14.4, 17.6, 21.7, 24.9 g kg^?1 DM) were formulated. Each diet was randomly assigned to triplicate group of 30 fish (3.58 ± 0.002 g, mean ± SEM) each tank for 8 weeks. The highest weight gain (WG, %), final body weight (g) and specific growth rate were recorded when phenylalanine level was 17.6 g kg^?1 of the diet. Fish muscle protein content, protein efficiency ratio (PER), feed conversion ratio and alanine aminotransferase were significantly affected by dietary phenylalanine level. The polynomial regression calculated using WG and PER indicated that the optimal dietary total aromatic amino acid (phenylalanine + tyrosine) requirement for juvenile grass carp was 24.4 g kg^?1 of the diet, corresponding to 65.9 g kg^?1 of dietary protein.     

Growth,partial energy balance,mantle and digestive gland lipid composition of Octopus vulgaris (Cuvier, 1797) fed with two artificial diets

Effects of two binders (gelatine and alginate) were tested on growth, survival, partial energy balance and lipid composition of mantle and digestive gland (DG) of Octopus vulgaris. The three diets tested were given as follows: CON, (Loligo gahi) as control, GEL, composed of squid paste (L. gahi) (300 g kg^?1), fish hydrolyse CPSP^® (100 g kg^?1) and fish meal (500 g kg^?1), agglutinated with 100 g kg^?1 of gelatine and ALG, composed of squid paste (L. gahi) (300 g kg^?1), fish hydrolyse CPSP^® (100 g kg^?1) and fish meal (500 g kg^?1), all agglutinated with 100 g kg^?1 of alginate. Growth rates were 13.7 ± 2.1, 2.1 ± 2.8 and ?2.4 ± 2.9 g kg^?1 bw day^?1, for octopuses fed CON, GEL and ALG diets, respectively. DGs of octopuses had higher concentrations of fatty acids (FA) than the mantle. DG of animals fed CON had higher concentrations of FAs than those fed the artificial diets. Energetic balance demonstrated that physiologically useful energy for maintenance E(B) was affected by type of diet, with negative values of E(B) in animals fed ALG and positive (85 and 154 kJ kg^?1 day^?1) in octopuses fed GEL and CON, respectively. The ALG diet did not cope with the physiological requirements for octopus growth.