Fish Feed Pellets Research Articles

Effects of Puerarin on the Reduction of Glucose and Promotion of Overall Health in Acutely Stressed Chinook Salmon, <I>Oncorhynchus Tshawytscha</I> (Actinopterygii: Salmoniformes: Salmonidae)

Background. Farmed fish reared in aquaculture systems are exposed to physiological stressors from biological, chemical, and physical sources. The consequences of these stressors affect the productivity of farming outcomes by reducing immune response, growth, and development within fish. A 24-h study was performed to determine the effects of supplementing puerarin—the most biologically active ingredient present in the roots of kudzu (Pueraria lobata )—within farmed fish on acute handling stress. Materials and methods. Fingerlings of Chinook salmon, Oncorhynchus tshawytscha , were maintained at 16‐18oC in 10 US gallon (37.8 L) glass tanks, supplied with recirculated and aerated dechlorinated water. Puerarin was given to fish through supplementation to commercial fish feed pellets. Acute handling stress was induced through transferring the fish from their housing tanks into 8 designated tanks at 0000 h. Subsequently, at 5 h post-transfer all the fish were fed to satiation, following which the stressed groups were chased with nets. Results. The results indicated that administration of puerarin through feed supplementation reduces plasma glu cose, hematocrit, plasma protein, and improves spleen somatic indices after 24 h, and thereby counteracting the negative consequences of acute stress induced through handling . Conclusion. The results suggest that supplementation of puerarin to commercial fish feed improved overall fish health through enhancing systemic circulation while attenuating plasma glucose. Being one of the first studies to study the effects of puerarin on fish, our results are in agreement with prior research with puerarin on other ani mal models .

Dispersal and Survival of Flavobacterium psychrophilum PhagesIn Vivoin Rainbow Trout andIn Vitrounder Laboratory Conditions: Implications for Their Use in Phage Therapy

Attention has been drawn to phage therapy as an alternative approach for controlling pathogenic bacteria such as Flavobacterium psychrophilum in salmonid aquaculture, which can give rise to high mortalities, especially in rainbow trout fry. Recently, phages have been isolated with a broad host range and a strong lytic potential against pathogenic F. psychrophilum under experimental conditions. However, little is known about the fate of phages at environmental conditions. Here, we quantified the dispersal and fate of F. psychrophilum phages and hosts in rainbow trout fry after intraperitoneal injection. Both phages and bacteria were isolated from the fish organs for up to 10 days after injection, and coinjection with both bacteria and phages resulted in a longer persistence of the phage in the fish organs, than when the fish had been injected with the phages only. The occurrence of both phage and bacterium was most prevalent in the kidney and spleen, with only minor occurrence in the brain. The experiment showed that injected phages were rapidly spread in the internal organs of the fish, also in the absence of bacteria. Parallel examination of the regulation of bacteriophage infectivity in controlled laboratory experiments at various environmental conditions showed that pH had only minor effects on long-term (3 months) phage infectivity within a pH range of 4.5 to 7.5, whereas phage infectivity was immediately lost at pH 3. In the absence of host cells, phage infectivity decreased by a factor of 10,000 over 55 days in untreated pond water, while the sterilization and removal of particles caused a 100-fold increase in phage survival relative to the control. In addition, F. psychrophilum-specific phages maintained their infectivity for ∼2 months in glycerol at -80°C, whereas infectivity decreased by a factor 10 when kept in a buffer at 20°C. Only a very small degradation in infectivity was seen when bacteriophages were added and dried on fish feed pellets. Together, these results indicate that application of bacteriophages represents a promising approach for the control of F. psychrophilum infections in trout and suggest fish feed as a potential delivery method.

Hyperspectral imaging based on diffused laser light for prediction of astaxanthin coating concentration

We present a study on predicting the concentration level of synthetic astaxanthin in fish feed pellet coating using multi- and hyperspectral image analysis. This was done in parallel using two different vision systems. A new instrument for hyperspectral imaging, the SuperK setup, using a super-continuum laser as the light source was introduced. Furthermore, a parallel study with the commercially available multispectral VideometerLab imaging system was performed. The SuperK setup used 113 spectral bands (455---1,015 nm), and the VideometerLab used 20 spectral bands (385---1,050 nm). To predict the astaxanthin concentration from the spectral image data, the synthetic astaxanthin content in the pellets was measured with the established standard technique; high-pressure liquid chromatography (HPLC). Regression analysis was done using partial least squares regression (PLSR) and the sparse regression method elastic net (EN). The ratio of standard error of prediction (RPD) is the ratio between the standard deviation of the reference values and the prediction error, and for both PLSR and EN both devices gave RPD values between 4 and 24, and with mean prediction error of 1.4---8.0 parts per million of astaxanthin concentration. The results show that it is possible to predict the synthetic astaxanthin concentration in the coating well enough for quality control using both multi- and hyperspectral image analysis, while the SuperK setup performs with higher accuracy than the VideometerLab device for this particular problem. The spectral resolution made it possible to identify the most significant spectral regions for detection of astaxanthin. The results also imply that the presented methods can be used in general for quality inspection of various coating substances using similar coating methods.

An Anaerobic Slurry Module for Solids Digestion and Denitrification in Recirculating Minimal Discharge Marine Fish Culture Systems

An anaerobic denitrification module with improved stability for closed aquaculture systems is described. The module was fitted to a recirculating fish mariculture system. The 18 m3 system consisted of a fish basin, a nitrification trickling filter and the module reported here, which was composed of a stirred slurry basin and two subsequent sedimentation tanks. Commercial fish feed (pellets) introduction into the slurry basin simulated nutrient input equivalent to 450 kg of fish biomass. About 50 kg of the sea bream, Sparus aurata, were introduced to bioassay water quality. Conditions remained stable as long as the mixing remained regular (16 wk). Feeding and sampling continued for an additional 6 wk of irregular mixing, during which time water quality gradually deteriorated causing 19% mortality of the stocked fish population. The system removed a majority of the total dissolved nitrogen (N) by denitrification and total phosphorus (P) by immobilization in the sludge. The rate of denitrification approached 9 mmol N/L/d. Hydrogen sulfide concentration in the fish basin remained low. The results constitute a proof‐of‐concept for the utility and resilience of slurry basins in the control of anaerobic processes and the maintenance of good water quality in recirculating fish culture.

Pengaruh Pemberian Kombinasi Pakan Ikan Rucah dan Pakan Buatan (Pelet) terhadap Pertumbuhan dan Laju Sintasan Rajungan (Portunus pelagicus)

The aim of this experiment was to find out the data and information of effect on feeding of combination of trash fish and pellet to the growth and survival rate of swimming crabs ( Portunus pelagicus ). The research was conducted in the research station of Research Institute for Coastal Aquaculture, Maros, South Sulawesi for 40 days. Nine aquaria were used in this research and the dimention were 60 x 40 x 40 cm. Experimental disign used the Complete Randomized Design, The treatments were applied of trash fish and artificial feed (pellet) i.e. A; 100% trash fish ( Clupea sp), B; 100% artificial feed (pellet), and C; 50% trash fish + 50% pellet, with three replicates, respectively, Crablet were applied average size of 5,2 + 0,2 mm in charapace width and 0,04 + 0,02 g in body weigth. Feeding were conducted of three times a day, with dosage 15 % of total body weight a day. During the experiment, the determined parameters were body weight, charapace width, and survival rate. The result showed that artificial feed/pellet of 42% protein contain could be used as feed in swimming crabs rearing and not significant different on the growth of charapace width, body weight and survival rate (P>0.05) with the other treatment.

Image Analysis of Pellet Size for a Control System in Industrial Feed Production

When producing aquaculture fish feed pellets, the size of the output product is of immense importance. As the production method cannot produce pellets of constant and uniform size using constant machine settings, there is a demand for size control. Fish fed with feed pellets of improper size are prone to not grow as expected, which is undesirable to the aquaculture industry. In this paper an image analysis method is proposed for automatic size-monitoring of pellets. This is called granulometry and the method used here is based on the mathematical morphological opening operation. In the proposed method, no image object segmentation is needed. The results show that it is possible to extract a general size distribution from an image of piled disordered pellets representing both length and diameter of the pellets in combination as an area.

Effect of Formula Variation in the Properties of Fish Feed Pellet

Most of fish feed pellet in market is low in terms of water stability and easily swell when it is immersed in water. Thus, the soluble vitamins and minerals will be easily leached out from the pellet. These will lead to the nutrient deficiency and environmental problems in fish tanks or ponds. Therefore, a study was conducted to minimise the degree of swelling and mineral leaching while the floating time is maximised. For these purpose several formulations of fish feed were made and tested. The formulation was based on common resources such as corn flour, soy flour and tapioca flour. To get water stability which is better floating time and lower leach ability, palm oil stearin was added as a main subject compound for this study. Statistical method, D-optimal crossed design of response surface methodology was used for the analysis and optimisation of the properties of fish feed pellet produced. In the statistical analysis, the physical properties such as degree of swelling, leaching and floating ability were chosen as the responses whereas pellets composition and processing temperature as the independent factors. The result shows there is a relationship between fish feed formulation and properties of fish feed pellet produced. The optimum of the floating time, leach ability and stability of fish feed pellet also can be obtained. © 2010 Asian Network for Scientific Information.

Drying and Storage Stability of a Probiotic Strain Incorporated into a Fish Feed Formulation

A Lactobacillus brevis strain was isolated from the gastrointestinal tract of rainbow trout (Oncorhynchus mykiss) fished from the BioBio Region (Chile) and dried in order to obtain a stable dehydrated product during storage. Fish feed pellets featuring Lactobacillus strain concentrations within the range 108–109 CFU/g and 5% moisture were obtained. Fluidized bed (air at 40°C) and rotary vacuum (49.21 kPa, 60°C) dryers were used to prepare those feedstock formulations that were able to maintain viability at 4 and 20°C. Fluidized bed convective heat transfer coefficients were estimated as 17.1 and 21.9 W/m2 K for feed pellets of 2 and 4 mm diameter, respectively. Decreasing drying rate period diffusion coefficients were calculated as 9.4 × 10−10 and 20.8 × 10−10 m2/s for feed pellets of 2 and 4 mm diameter, respectively.

Partial recovery of infaunal communities during a fallow period at an open-ocean aquaculture

Open-ocean or offshore aquaculture has attracted recent controversy for its potential environmental impacts and proposed expansion in the USA. Organic enrichment of benthic marine communities has been documented extensively under nearshore fish farms — primarily from fish feces and feed pellets — but relatively few studies have examined the effects of deeper, offshore operations. In this study, we investigate the effects of a 6 mo non-operational fallow period on ben- thic invertebrate communities surrounding a commercial offshore fish farm. Polychaete species diversity and community structure were analyzed at distant reference sites and farm-adjacent affected sites before, during and after the fallow period. The relative abundances of 3 polychaete indicator species for organic enrichment were also analyzed. During the fallow period, community structure at affected sites became more similar to communities at distant reference sites. Additionally, the sudden disappearance of enrichment indicator species at previously affected sites during the fallow period further suggests the beginnings of a recovery. However, species diversity did not increase significantly during the fallow period, indicating that the affected communities had not been fully restored to pre-culture or distant reference conditions. This study demonstrates the potential environmental benefits of scheduled fallow periods or crop rotations in offshore aquaculture.

DEVELOPMENT OF AN SMALL EXPRESSION MACHINE TO PURPOSE PRODUCTION OF FISH FEED PELLETS

Field experiment were carried during 2007 at the Sakha Aquaculture Research Station, Kafr El-Sheikh, Governorate, to evaluate the feasibility of using a small expression machine for oil extraction to suit production of fish feed pellets. The effect of some parameters such as, screw speeds (1.50, 1.90, and 2.25 m/s), moisture content of ration (12.8, 16.5, and 22.0 % ), screw pitch (50.0 and 80.0 mm) and two different die shape (Perforated Cylinder - Internal Cone) on energy requirements, machine productivity, pellets bulk density, pellets durability, floating time and pelleting efficiency. The obtained results showed that increasing screw speed from (1.50, 1.90,and 2.25 m/s) tends to increase machine productivity from ( 0.31, 0.37, and 0.47 ton/h), pellets durability from (92.5, 93.4, and 95.66 %), floating time from (270, 295, and 330 min.) and pelleting efficiency from (96.4, 97.2, and 98.4 %), respectively. And decreasing energy requirements from ( 9.27, 8.59 and 7.45 kW.h/ton), and pelleting bulk density from (0.96, 0.81 and 0.74 gm/cm3), respectively. Increasing ration moisture content from ( 12.8, 16.5, and 22.0 %) led to increase energy requirements from ( 7.31, 7.95 and 9.27 kW.h/tom), floating time from (240, 250, and 270 min.) and pelleting durability from (92.50, 93.40, and 95.66 %), respectively. And decreasing machine productivity from (0.31, 0.26, and 0.23 ton/h), pellets bulk density from ( 0.96, 0.90, and 0.86 gm/cm3 ) and pellets efficiency from (98.4, 97.9, and 97.2 %), respectively.

The influence of fish feed pellets on the stability of seabed sediment: A laboratory flume investigation

Superfluous fish food settling below fish farms can have a negative impact on the seabed. To aid in the assessment of this impact a series of flume experiments, designed to mimic seabed conditions below a fish farm, was conducted with the aim of examining the effects of fish pellets on the stability of fine sediments. Artificial beds, with varying quantities of fish pellets incorporated both within the sediment matrix and lying on the sediment surface, were allowed to consolidate for different periods of time ranging from 1 to 10 days, and then subjected to erosion experiments. In flume experiments containing fish pellets, a bacterial biofilm developed at the sediment-water interface after a few days. In the control experiments (no fish pellets), a diatom biofilm caused extensive stabilisation of the surface sediment. The erosion experiments showed that the addition of fish pellets reduced the surface erosion threshold by more than 50%. The stability decrease was more pronounced in the experiments with greater amounts of pellets. Evidence of drag reduction due to high suspended sediment concentration was also observed. This phenomenon is discussed and a correction formula is proposed for the effective shear stress experienced by the bed.

The settling behavior and benthic transport of fish feed pellets under steady flows

Settling and erosion experiments were carried out on a size range of fish feed pellets using an annular flume. A strong positive correlation was observed between settling rate and pellet dimension (pellet length, pellet dimeter, and equivalent sedimentation diameter). Erosion thresholds also showed a strong positive correlation with pellet dimensions. Experiments were also carried out to examine the effect of the number of pellets on erosion threshold of two sizes. The results show an asymptotic increase in erosion threshold with increasing number of pellets present, possibly due to sheltering effects. The chemical composition of the pellets was analyzed in terms of water and organic, carbon, and nitrogen contents as well as stable carbon and nitrogen isotopes. The results arising from this study will provide, information regarding potential tracers of waste feed material and help validate model predictions associated with dispersal of waste material.

GROWTH PERFORMANCE OF FISH REARED UNDER DIFFERENT DENSITIES IN SEMI-INTENSIVE AND EXTENSIVE EARTHEN PONDS

ffect of stocking density on fish performance has been investigated in earthen ponds over five months of growing period in polyculture system including Nile tilapia, common carp, silver carp, mullet and African catfish. Experimental ponds have been allocated to various stocking rates of 1, 1.25, 1.5, 1.75, 10 and 14 fish/m 3 . The treatments of 10 and 14 fish/m 3 represented the semi-intensive system, while lower densities represented the extensive calture system. Fish in all treatments received 25% crude protein pelleted fish feed at rate of 3% of body weight that was adjusted throughout the growing period. Feed was offered twice/day for five days/week. Water quality has been monitored monthly. The physico - chemical analysis showed two distinct sets of values for the extensive and the semi-intensive stocking densities concurred with for the main water quality parameters, whereas the values of pH, E.C., salinity, alkalinity, hardness, total phosphorus and orthophosphate were significantly higher in extensive system than the semi-intensive one, while values of D.O, SD, NH3, NO2, NO3 were higher in the semiintensive system compared to the extensive system. Plankton communities expressed as Chlorophyll a was significantly higher in the extensive ponds. Average production was significantly higher in semiintensive ponds compared to the extensive ponds. However, for the main fish species (Nile tilapia), the average weight as well as the daily gain did not vary among treatments, while there were some differences with regard to average weight for other species. There was no difference concerning the condition factor in all treatments for any of the tested species. The

Reliable pneumatic conveying of fish feed

Fish feed pellets are susceptible to damage and valuable feed can be lost during pneumatic conveying of feed pellets from the feed barge to the sea cages. Experiments were designed to determine the lowest airflow rate necessary for reliable conveying without risk of pipe blockage and damage to the product at different product flow rates. The technical quality of the feed was assessed by use of three different methods: (1) the Holmen durability tester; (2) pellet strengths in diametrical compression and Weibull analysis; and (3) in an impact tester with use of high-velocity photography.Reliable conveying conditions were determined for product flow rates in the range 0.17–0.83kgs−1 and air mass flow rates in the range 0.18–0.23kgs−1. A plot of the feed pellet flow rate that ensured safe conveying as a function of the rpm of the air mover (roots type blower) showed a linear relation. Only 0.7% of the feed were lost when transported at the highest inlet air velocity tested. The Holmen durability was high, 98.9%, and the feed pellet strengths could adequately be represented with the Weibull distribution with a value for the modulus, m of 10.1 and the 37% Weibull strength at failure was 355kPa. Impact fracture was not seen at a particle velocity of 15ms−1, but fracture (chipping and cleavage) was triggered off at a particle velocity of 20ms−1, and destructive fracture was observed at 30ms−1.The value for the Weibull modulus, m is the highest reported in feed pellets, good technical quality of the feed is one reason for the low product loss during transportation. In addition, the result of the impact experiment suggests that the particle velocities during transportation were less than that required for causing fracture in the feed particles. Different meal sizes transported to the fish requires specific levels of air mass flow rates, and it is suggested that optimum air supply can be provided by controlling the rpm of the blower.

Laboratory trials on the effects of different diets on growth and survival of the common whelk, Buccinum undatum L. 1758, as a candidate species for aquaculture

Newly hatched juvenile Buccinum undatum can be reared under laboratory conditions. Good was growth is achieved when juveniles were fed on combined diets (blue mussel, cod, and fish pellets). Juveniles reached shell heights of 33.0 ± 4.2 mm, 26.9 ± 3.8 ± mm, 23.2 ± 2.2 mm, and 20.1 ± 1.6 mm, after 14 months of fedding on a combined diet, blue mussel, cod, and fish pellets, respectively under ambient sea temperature and salinity. After 14 months juveniles fed blue mussel had the highest survival rates (67%) followed by those fed a combination of all other experimental diets (61%), cod waste (53%) and fish-feed pellets (46%). High mortalities were recorded in most treatments during the summer months between June and September. This species appears to have an aquaculture potential, as juveniles readily feed on artificial diets at an early age, show high survival rates and could potentially reach market size in 2 years or less. The major constraint in realising this potential at present, is the relatively low value of the species; if market values increased as a result of serious depletion of natural populations, hatchery production of juveniles for intensive aquaculture or restocking could become economically viable.

Appropriate Timing of Supplemental Feeding for Production of Nile Tilapia, Silver Carp, and Common Carp in Fertilized Polyculture Ponds

AbstractIn an attempt to identify appropriate times for initial application of supplemental feed in polyculture fertilized fish production earthen ponds, a study was conducted for 19 wk to establish the growth performance, yield, survival, and body composition of Nile tilapia, common carp, and silver carp as influenced by four different feeding regimens (treatments). The four treatments were: 1) supplemental feeding beginning at onset of the experiment (T‐I) (control treatment); 2) 6‐wk delay of feeding after fish stocking (T‐II); 3) 13‐wk delay of feeding after fish stocking (T‐III), and 4) no supplemental feed application (T‐IV). Two ponds were assigned to each treatment and each pond was stocked with a similar number and weight of each fish species. A commercial pelleted fish feed (25% protein) was used to feed fish in T‐I, T‐II, and T‐III at 3% of their body weight, twice a day. At the end of the experiment, fish species (except for silver carp) in T‐II showed weight gain, growth rates, and yields significantly higher than fish in T‐III or T‐IV. Also, the total fish production and net profit in T‐II were significantly higher than in T‐III or T‐IV. Fish species in T‐II showed weight gain, growth rates, survival rates, and yields similar to those of T‐I (control treatment) with no significant differences. The amount of feed consumed by fish in T‐II was reduced by approximately 7.3% compared to that consumed by fish at T‐I. Moreover, there was increase in th net profit in T‐II by 4.8% over that achieved in T‐I. Therefore, T‐II appears to be the most appropriate among the tested feeding treatments and recommended for use in order to achieve the best growth, production, and net profit.

Effects of feeding rates on growth and production of Nile tilapia, common carp and silver carp polycultured in fertilized ponds

In an attempt to identify appropriate feeding rates for multispecies of fish raised in fertilized earthen ponds, the present work was conducted over a 19-week experimental period to establish the growth performance, production and body composition of Nile tilapia, common carp and silver carp fed 0.0%, 0.5%, 1.0%, 3.0%, 5.0% biomass and to apparent satiation (treatments). Twelve ponds were stocked with a similar number and weight of each fish species. Two ponds were assigned to each of the treatments, and a 25% protein pelleted fish feed was used to feed fish at the specified rate of feeding. At the end of the experiment, growth, weight gain, survival, yield and body composition of fish groups were affected by the treatments. The economic effectiveness also varied among treatments. The most conspicuous attribute of the feeding rates was its lack of influence on growth (g day−1), weight gain (g per fish), yield (kg ha−1) or body composition of silver carp. The results of whole-body proximate analysis indicated that various feeding rates had either an irregular pattern or no effects on the protein and ash gain per 100 g of fish body weight (bw) gain. The most notable exceptions were significant (P < 0.05) increases in body fat and gross energy gains in Nile tilapia, common carp and silver carp accompanied by decreases in percentages of moisture (but not in silver carp) as feeding rate increased. Among the six different feeding levels, feeding to apparent satiation (feed amount was equivalent to 2.67% of fish bw day−1) appeared to be optimal, as it significantly (P < 0.05) supported the highest fish production, income and net profit compared with all other treatments except for the 3% feeding level, for which the differences in those measurements were comparable.

Development of a Lag Time Coating for Drug-Layered Fish Feed Pellets

The purpose of this work was to develop a release-delaying coat for drug-layered fish pellets, in order to prevent a premature release of the drug in the tank water but allowing a rapid release after uptake by the fish. Blank pellets were prepared in a rotary processor and drug layered in a Wurster coater with bovine serum albumin or riboflavin using hydroxypropyl methyl cellulose (HPMC) as a binder. On the drug- loaded pellets, different mixtures of ethyl cellulose (EC) and HPMC were applied as the release-delaying coat. The aim was to obtain less than 10% drug release during the first 10 min followed by a fast release after the “lag” period, resulting in a sigmoidal release profile. In order to prevent coat bursts it was necessary to increase the amount of plasticizer from 20 to 40% triethylcitrate. To have a complete coat around the pellets, the thickness of the coat (amount EC) was important up to a certain level. The EC/HPMC ratio had a decisive influence on optimizing the permeability of the coating and realizing a sigmoidal release profile. The release rate was studied as a function of several formulation variables and physico-chemical parameters (salinity, pH, and temperature) of the dissolution medium as the coating system is intended for different fish species. Salinity of the water proved to be important as well as the temperature. The developed system seems to be promising for a lot of ichthyologic applications, although it has to be evaluated for each intended drug, keeping in mind the properties of the particles to be coated, the fish species, and the environment.

Pellets as a dosage form for drugs in aquaculture: technological aspects

Fish feed pellets are usually manufactured by extrusion of a steam-conditioned meal. However, since high temperatures are involved in this process, it is often not suitable for incorporation of drugs. The pharmaceutical industry uses a variety of pelletization techniques to cope with this problem. To the pharmaceutical industry, pellets are spherical particles with a diameter between 0.25 and 1.5 mm. The most popular pharmaceutical pelletization processes nowadays are the layering of drugs onto inert cores and the extrusion-spheronization process. Other processes such as the wet granulation technique in the rotary processor seem to be promising. This wet granulation technique in the rotary processor was used to produce pellets containing a gonadotropin-releasing hormone analogue and penetration enhancers. This pellet formulation was able to induce ovulation in fish.

Influence of fish meal quality and feed pellet on growth, feed efficiency and muscle composition in gilthead seabream ( sparus aurata)

The effect of fish meal quality on growth, feed efficiency, protein digestibility and fillet composition was studied in a growth experiment with gilthead seabream. The experiment included a comparison of pelleted feed with extruded feed. The fish were fed three extruded diets which varied in the quality of the fish meal used in the respective feeds: low quality fish meal, good quality fish meal, and a mixture (50%) of the two fish meal qualities. Fish meal quality was judged by protein digestibility as measured with mink as the test animal and by the content of biogenic amines. A fourth experimental group was fed a pelleted feed with the same mixed fish meal blend. The experiment started with 70 g seabream and lasted for 3 months until the fish reached about 160 g. All groups showed good growth and feed efficiency during the experimental period, with daily specific growth rates (SGR) of 0.90–1.00% and feed efficiencies (FE; fish weight gain per feed offered) from 0.58 to 0.66. The fish fed the feed with low quality fish meal showed significantly poorer feed efficiency than the other groups, and there was a significant correlation between feed efficiency obtained in seabream and the protein digestibility as measured with mink. No difference was observed among groups fed the extruded diets, for growth, fillet composition or amount of liver or viscera, although a significant correlation was obtained between SGR and protein digestibility in mink. Fillet lipid content was higher in fish fed the extruded feed, compared with those fed the corresponding pelleted diet. Protein digestibilty in seabream showed no difference among the extruded feeds, while the pelleted feed was significantly lower.