Seasonal and sex differences in energy reserves of red snapper <Emphasis Type="Italic">Lutjanus campechanus</Emphasis> on natural and artificial reefs in the northwestern Gulf of Mexico

To evaluate the energetic condition of red snapper inhabiting natural and artificial reefs in the Gulf of Mexico, the liver-somatic index (LSI) and muscle tissue caloric density (CD) were measured for fish collected between September 2011 and October 2013. Liver energy reserves were highest in spring and decreased during summer, with greater LSI values at natural reefs in spring. While female red snapper LSI was greater than males at the natural reefs, indicating a larger energetic investment for spawning, it did not differ between males and females at the artificial reefs. Females at natural reefs have the ability to invest more energy in reproduction than females at artificial reefs, which is reflected in larger female LSI values at the natural reefs. Caloric density was highest in winter and decreased through fall at the natural reefs, with the opposite trend observed at artificial reefs. Muscle energy reserves are likely utilized for gonad development, while stored liver energy is utilized during and after spawning. Female red snapper at natural reefs can exhibit greater energy reserves, and thus a higher energetic condition than females at artificial reefs. Recognizing that energetic condition differs between habitats could enhance future red snapper stock assessments.     

Annual changes in distribution depths of bighand thornyhead <Emphasis Type="Italic">Sebastolobus macrochir</Emphasis> off the Pacific coast of northern Honshu,Japan

ABSTRACT:   Body size dependent distribution patterns of bighand thornyhead Sebastolobus macrochir were examined using bottom trawl surveys in the Tohoku area, off the Pacific coast of northern Honshu, Japan. In northern and southern Tohoku, distribution depths of ≤10-cm standard length (SL) fish increased from 500–600 m in 2003 to 600–700 m in 2005 with an increase in density of 11–20-cm SL fish at depths of 500–600 m. In 2004–2005, small fish (≤10 cm SL) were distributed in deeper waters than large fish (11–20 cm SL). In ≤20-cm SL fish, the main distribution depths changed from 300–600 m in 1997–2002 to 500–600 m in 2003 in southern Tohoku, but not in northern Tohoku. Stepwise multiple regression analysis showed that negative correlations were found in biomass densities between a few demersal fish species and bighand thornyhead at depths of 300–400 and 400–500 m in southern Tohoku. These results suggest that distribution of bighand thornyhead was affected by intra- and interspecific competitions in the Tohoku area.     

The Value of a Net‐Cage as a Fish Aggregating Device in Southern California

There is an urgent need for primary data that can be used to quantify the value of marine aquaculture facilities that also describe influences on the surrounding natural ecosystem and its wild fish communities. Divers completed 360 transect replicates below a net‐cage and at nearby and distant rocky reefs off Catalina Island, California, estimating the species abundance and size class of all conspicuous fishes in the water column. We observed 10,234 fishes aggregating below the net‐cage with a mean annual density of 142 (SE ± 30) per 100 m² and diversity H′ 2.29. At the adjacent reference reef, we counted 8452 fishes with a mean annual density of 117 (SE ± 20) and H′ 1.45 and at Reference Reef 2, located 500 m away, there were 8958 fishes with a density of 124 (SE ± 20) and H′ 1.13. The total density of fishes was the same between the study sites (ANOVA; P = 0.24); however, the spatial density of fishes in the water column was different between the net‐cage and reference reefs. Additionally, the density of juvenile fish was significantly lower at the net‐cage (ANOVA; P = 0.02), while the density of subadult and adult fishes was higher (ANOVA; P = 0.03). Feeding guild analysis ranked the net‐cage highest (3507), while Reference Reef 1 (2149), and Reference Reef 2 (2241), had lower values, a relationship often found between artificial and natural reefs. This suggests the importance of available trophic resources to the adult population of wild fishes, and has implications in the artificial reef attraction–production debate. The results of this study not only reproduce a pattern of fish attraction to net‐cages in the marine environment reported in previous studies but also demonstrate a relative habitat value compared in both time and space, of the fish community at a net‐cage compared with vibrant kelp bed communities.     

Initial response of a floodplain lake fish community to water-level stabilisation

Abstract –  Many floodplain lake fish communities have been influenced by large-scale shifts in processes of water-level stability that degrade habitat quantity and quality. Efforts to restore rivers and their floodplains have recently taken a priority yet many restoration approaches are in their developmental stages and potentially controversial. We measured fish community changes in response to a water stabilisation technique in an Illinois River floodplain lake, achieved by levee renovations in 1997, using data collected prior to (1991–1993) and after (2000–2002) stabilisation. Our results indicate fish community composition (presence/absence) showed little variability and did not differ ( R  = 0.037; P  = 0.60) between the two time periods; whereas, fish community structure (abundance) differed ( R  > 0.50; P  ≤ 0.10). Increased abundances of desirable species like gizzard shad Dorosoma cepedianum (Lesueur), white crappie Pomoxis annularis (Rafinesque), black crappie Pomoxis nigromaculatus (Lesueur) and largemouth bass Micropterus salmoides (Lacepede), coupled with declines of less desirable species like common carp Cyprinus carpio (Linnaeus) contributed to community changes. These changes suggest positive responses to water stabilisation practices that may act as an intermediate step in restoring river–floodplain function in certain situations.     

Survival and movement of hatchery-reared red snapper on artificial habitats in the northern Gulf of Mexico

Abstract  Hatchery-reared age-0 red snapper, Lutjanus campechanus (Poey), were released onto artificial habitats in the Gulf of Mexico. Fish showed 12.7% survival after 7 months on small habitats (0.86 m³) and 3.1% survival after 8 months on large habitats (3.9 m³). Emigration was estimated by the movement of fish to unstocked habitats and accounted for 76.8% of the total decline in abundance at release sites after 26 days. Fish showed higher survival and growth rates on small habitats (27.6% at 26 days; 0.33 mm day⁻¹) compared with large habitats (13.2% at 34 days; 0.26 mm day⁻¹), which may have been due to increased predation and competition on large habitats. Fish became evenly distributed among adjacent habitats 26 days after release, indicating that stocking densities at release habitats were above carrying capacities. These observations suggested that providing additional habitat around red snapper release sites would increase survival.     

Comparison of pelvic fin rays, scales and otoliths for estimating age and growth of bull trout, Salvelinus confluentus

Abstract  The suitability of three anatomical structures to determine age and growth of bull trout, Salvelinus confluentus (Suckley), was assessed. Scales and pelvic fin rays collected from recaptured bull trout 96–265 mm TL were used to validate annulus formation and assess the accuracy and precision of back calculation. Ageing precision and agreement of assigned ages were compared among scales, fin rays and otoliths from bull trout 52–711 mm TL. Annulus formation was validated for 88% (14 of 16 fish) of recaptured bull trout using pelvic fin rays and 68% using scales (15 of 22 fish). Annulus formation in fin rays occurred between late April to early June, and the hyaline (non-growth) band began forming in late August. Back-calculated length was not significantly different from measured length at initial capture either for fin rays or scales ( P  ≥   0.19), and absolute percent error was 7.2 ± 1.2 (mean ± SE; n  =   14) for fin rays and 8.7 ± 1.9 ( n  =   15) for scales. Consistency of back-calculated lengths at age between tag and recapture samples for individual fish was similar for fin rays (mean absolute difference = 8.2% ± 0.9; n  =   33) and scales (9.4% ± 1.4; n  =   40). However, fin rays (87% precision) and otoliths (90%) provided notably higher ageing precision than scales (68%) and closer agreement of assigned ages, particularly for fish older than age 4. Pelvic fin rays appear to offer more accurate and precise age and growth determinations than scales and a non-lethal alternative to otoliths, but further work is needed to validate the accuracy and precision of ageing large, migratory bull trout.     

Beyond the reef: The widespread use of non‐reef habitats by coral reef fishes

Marine ecology seeks to understand the factors that shape biological communities. Progress towards this goal has been hampered by habitat‐centric approaches that ignore the influence of the wider seascape. Coral reef fishes may use non‐reef habitats (e.g. mangrove and seagrass) extensively, yet most studies have focused on within‐reef attributes or connectivity between reefs to explain trends in their distribution and abundance. We systematically review the evidence for multihabitat use by coral reef fishes across life stages, feeding guilds and conservation status. At least 670 species of “coral reef fish” have been observed in non‐reef habitats, with almost half (293 species) being recorded in two or more non‐reef habitats. Of the 170 fish species for which both adult and juvenile data were available, almost 76% were recorded in non‐reef habitats in both life stages. Importantly, over half of the coral reef fish species recorded in non‐reef habitats (397 spp.) were potential fisheries targets. The use of non‐reef habitats by “coral reef” fishes appears to be widespread, suggesting in turn that attempts to manage anthropogenic impacts on fisheries and coral reefs may need to consider broader scales and different forms of connectivity than traditional approaches recommend. Faced with the deteriorating condition of many coastal habitats, there is a pressing need to better understand how the wider seascape can influence reef fish populations, community dynamics, food‐webs and other key ecological processes on reefs.     

The suitability of anadromous Arctic charr as host and vector of the monogenean Gyrodactylus salaris

Abstract –  In 2000, the Atlantic salmon ( Salmo salar L.) stock in the river Signaldalselva, North Norway was found to be infected with the monogenean Gyrodactylus salaris (Malmberg). This river system has a multispecies fish community of nine species in total. Low densities of Atlantic salmon parr were found during electrofishing in October (2003) with a prevalence of 94% and a mean abundance of 848 G. salaris. This watercourse also holds a riverine stock of anadromous Arctic charr ( Salvelinus alpinus ), which is not common in Norway. Among the parr of Arctic charr, 64% were infested with an abundance of 23 parasites per fish. The most heavily infected 0+ and 1+ juvenile Arctic charr had 469 and 534 parasites, respectively, indicating that the parasites are able to reproduce on Arctic charr in the wild. There was little variation in the rates of infestation of Arctic charr along the studied stretch of the river, even in areas with very low densities of Atlantic salmon parr. The parr of anadromous Arctic charr seem to be suitable as long-term hosts for G. salaris . Moreover, a few (22%) infested adult sea-running Arctic charr were captured after ascending the river in the autumn, which shows that large fish may also act as carriers of G. salaris . However, no parasites were recorded on potential anadromous Arctic charr before descending during early spring (April 2003 and April 2004). Thus, it is still not clear whether anadromous Arctic charr are able to disperse the parasite between watercourses. So far, it is uncertain whether G. salaris may increase the mortality rates of Arctic charr and thereby be a threat to these unusual occurring riverine anadromous Arctic charr stocks.     

Evaluation of tuna by‐product meal as a protein source in feeds for juvenile spotted rose snapper Lutjanus guttatus

This study evaluated the use of tuna by‐product meal (TBM), a locally produced feed ingredient, as a replacement for fish meal (FM) in diets for spotted rose snapper, Lutjanus guttatus. Six isonitrogenous compounds [480 kg^?1 crude protein (CP) and isoenergetic diets (21 kJ g^?1)] were formulated to replace 0 (D‐0%), 10 (D‐10%), 20 (D‐20%), 30 (D‐30%), 40 (D‐40% or 50% (D‐50%) of FM protein with TBM protein. Each diet was fed to four replicate groups of spotted rose snapper (initial weight 5.4 g ± 0.04 g) to apparent satiation three times a day. After 8 weeks of feeding, the fish gained 4–5 times their initial weight. Spotted rose snapper fed D‐30% had a significantly higher specific growth rate (2.7% day^?1) than fish fed the other diets containing lower or higher amounts of TBM. Haematological parameters and whole‐body proximate composition were unaffected by diet (P > 0.05). The ADC for protein and energy in D‐0%, D‐20% and D‐30% were significantly higher than those for the D‐40% and D‐50% groups. A broken line model indicated that 262 g kg^?1 TBM in the diet would yield maximum growth of the spotted rose snapper. The results of this study demonstrate that TBM is an acceptable ingredient for replacing 25–30% of dietary protein from FM in spotted rose snapper diets but that higher replacement levels reduce fish performance.     

Fish assemblages associated with artificial reefs of concrete aggregates or quarry stone offshore Miami Beach,Florida, USA

Few studies have compared the suitability of different artificial reef construction materials in terms of their efficacy in acquiring diverse faunal assemblages. We compared the fishes associated with 12 co-located reefs constructed of limestone quarry boulders, concrete-gravel aggregate, or concrete-tire aggregate (four of each substrate) in 7 m of water, 200 m offshore Miami Beach, Florida, USA. All 12 reefs were deployed 100 m apart the same day in two lines of six. The four quarry stone reefs consist of a pile of 50 boulders each. The remaining eight reefs, of concrete-gravel aggregate and concrete-tire aggregate, were each constructed with 25 1.5 m edge and 25 1.2 m edge tetrahedron modules. Every two months from October 1998 to February 2001, SCUBA divers recorded fish species, abundance, and length, as well as spiny lobster, Panulirus argus, abundance. One hundred and forty-six species of fishes were recorded during the study period. The abundance and species richness of fish on each treatment exhibited a significant (p<0.05) seasonal variation with summer months having the greatest numbers and winter the lowest. There was no significant difference in total fish or spiny lobster abundance or fish biomass amongst the three reef types (p>0.05). Likewise, multi-dimensional scaling of Bray-Curtis dissimilarity indices did not indicate clustering of fish assemblages by reef type. Comparison of pre-deployment fish counts from the reef sites and neighboring hard bottom and jetty with counts from the same sites two years post-deployment indicate the artificial reefs increased both fish abundance and richness in the local area.     

Vitrification of sperm from marine fish: effect on motility and membrane integrity

Our goal was to develop a standardized approach for sperm vitrification of marine fish that can be applied generally in aquatic species. The objectives were to: (i) estimate acute toxicity of cryoprotectants over a range of concentrations; (ii) evaluate the properties of vitrification solutions (VS); (iii) evaluate different thawing solutions and (iv) evaluate sperm quality after thawing by examination of motility and membrane integrity. Sperm were collected from red snapper (Lutjanus campechanus), spotted seatrout (Cynoscion nebulosus) and red drum (Sciaenops ocellatus). A total of 29 combinations of cryoprotectants were evaluated for toxicity and glass formation. Samples were loaded onto 10‐μL polystyrene loops and plunged into liquid nitrogen. There was a significant difference (P < 0.05) in post‐thaw motility among VS and among species when using the same VS. The sperm in VS of 15% DMSO + 15% ethylene glycol + 10% glycerol + 1% X‐1000^? + 1% Z‐1000^? had an average post‐thaw motility of 58% and membrane integrity of 19% for spotted seatrout, 38% and 9% for red snapper, and 30% and 19% for red drum. Adaptations by marine fish to higher osmotic pressures could explain the survival in the high cryoprotectant concentrations. Vitrification offers an alternative to conventional cryopreservation.     

舟山群岛外海域春秋季鱼类群落结构及生物多样性

为了解舟山群岛外海域鱼类资源状况,于2018年4月(春季)和10月(秋季)在舟山群岛外海域进行的渔业资源调查,用得到的数据分析了鱼类种类组成、优势种、群落结构及生物多样性。结果显示:(1)舟山群岛外海域鱼类有106种,隶属于12目47科80属;(2)本次调查鱼类种类数春季为63种,秋季为85种,总体与历史调查结果相比春季明显减少,而秋季却略有增加;(3)2个季节的鱼类优势种更替明显,春季优势种为黄鮟、日本红娘鱼和细条天竺鲷,秋季优势种为细条天竺鲷和日本发光鲷;(4)鱼类生物多样性指数值为秋季大于春季,春、秋季均匀度指数(J')对比多样性指数(H')和丰富度指数(D)都较小,且春、秋季生物多样性指数值基本都是随着水深的增加而增加,均以80 m以上水深区间较高;(5)通过聚类分析与非度量多维标度排序分析可得,春季在35%的相似水平上分为3个群落,秋季在45%相似水平上分为2个群落,秋季物种相似度比春季高,春季在生物量和丰度水平上均比秋季低。研究表明,舟山群岛外海域的春季鱼类群落结构可能处于未受干扰状态,秋季鱼类群落结构可能处于严重干扰状态。     

Fixed‐station monitoring of a harbour wall community: the utility of low‐cost photomosaics and scuba on hard‐substrata

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Study of growth and body composition of red snapper <Emphasis Type="Italic">Lutjanus erythropterus</Emphasis> fed diets containing <Emphasis Type="Italic">Escherichia coli</Emphasis> expressing recombinant tilapia insulin-like growth factor-I

ABSTRACT:   To examine the effects of insulin-like growth factor (IGF)-I on the growth performance of fish, juvenile red snapper Lutjanus erythropterus with an initial body weight of approximately 12 g were fed diets containing different amounts of IGF-I containing Escherichia coli BL21 powder (BL21-tIGF-I). The growth of fish was enhanced by lower doses (0.25, 0.5 and 1%), but deteriorated at higher amounts (2.5 and 5%). The best results were obtained with 0.5% BL21-tIGF-I supplementation, which resulted in 154 and 85% weight gain and feed efficiency, respectively. In addition, muscle proteins appeared to be elevated, but muscle lipids were reduced except for in the 1% BL21-tIGF-I group. In contrast, liver lipids were reduced at 0.25, 0.5 and 1%, but increased at 2.5 and 5% BL21-tIGF-I. Furthermore, to examine the effects of BL21-tIGF-I on later-stage red snapper, we selected fish of approximately 23–24 g weight and fed them a diet either with or without 0.5% BL21-tIGF-I for 12 weeks. Results showed that the growth performance of later-stage fish was better with BL21-tIGF-I than those without supplementation after 6 weeks of feeding. The average body weight of fish that did not receive BL21-tIGF-I during the first 6 weeks, but were fed BL21-tIGF-I in weeks 7–12, was significantly higher than those fed without BL21-tIGF-I for the entire experiment. These results suggest that a continuous supply of BL21-tIGF-I may be beneficial for the growth performance of red snapper.     

Discard composition and release fate in the snapper and grouper commercial hook-and-line fishery in North Carolina, USA

Abstract  Minimum size limits may be ineffective for reef fishes because they often sustain barotrauma when caught from deep (>20 m) waters. A study was undertaken in conjunction with hook-and-line commercial fishermen to calculate discard percentages and evaluate potential release mortality of eight economically important species: black sea bass, Centropristis striata (Linnaeus), red grouper, Epinephelus morio (Valenciennes), snowy grouper, Epinephelus niveatus (Valenciennes), gag, Mycteroperca microlepis (Goode and Bean), scamp, Mycteroperca phenax (Jordan and Swain), vermilion snapper, Rhomboplites aurorubens (Cuvier), white grunt, Haemulon plumieri (Lacepède) and red porgy, Pagrus pagrus (Linnaeus). Fishing with baited hook and line occurred in 2004 and 2005 in Onslow Bay, NC, in waters 19–150 m deep. Sub-legal discard rates were 15% for vermilion snapper, 25% for red porgy, 7% for red grouper, 33% for gag, 35% for scamp and 12% for black sea bass. Although mortality based on post-release behaviour was relatively low, higher mortalities estimated from models incorporating hooking location and depth of capture suggest that minimum size limits may not provide the population benefits intended by management in the North Carolina reef fishery.     

Testing in situ avoidance reaction of vendace, Coregonus albula, in relation to continuous artificial light from stationary vertical split-beam echosounding

Abstract  The in situ avoidance reaction of vendace, Coregonus albula L., in relation to continuous artificial light in terms of a scaring device was tested by split-beam echosounding. The tests were carried out in the mesotrophic Bigge Reservoir (Germany) in November 2007 and 2008 using a Simrad EK 60 echosounder (120 kHz). An underwater lamp with light turned on and off was lowered to 30 m water depth at four sampling sites. No reaction of vendace was observed for the sampled references (light off), but strong avoidance behaviour by swimming mainly downwards was observed when the light was turned on. The light avoidance reaction was confirmed by the volume backscattering strength ( S _v) and calculated fish densities (fish ha⁻¹). The mean fish densities for the samples carried out with light turned on were lower (268 fish ha⁻¹, ±409 SD, n  =   32) than for the references with light turned off (5028 fish ha⁻¹, ±2317 SD, n  =   56). The related median values (33 and 3726 fish ha⁻¹, respectively, n  =   88) differed significantly (Mann–Whitney test, P  = <0.001). In conclusion, artificial light has great potential to scare pelagic vendace from areas near the bottom outlets of reservoirs to prevent entrainment losses.     

Effect of different dietary levels of commercial wood charcoal on growth,body composition and environmental loading of red tilapia hybrid

A 60‐day feeding study was performed to evaluate the role of dietary commercial wood charcoal (CWC) in fish growth performance, body composition and water quality of fingerlings red tilapias (Oreochromis mossambicus × Oreochromis niloticus). Four levels of charcoal (10, 20, 30 and 40 g kg^?1) were added to the control diet (0 g kg^?1 CWC) and fed to red tilapias (initial weight of 1.20 ± 0.04 g). At the end of the feeding trial, the fish weight gain, specific growth rate, feed conversion ratio, protein efficiency ratio and energy retention of the fish groups fed 30 and 40 g kg^?1 (CWC) in diet were significantly (P < 0.05) higher comparing with all other tested fish groups. Moreover, some proximate composition such as crude protein and nitrogen retention efficiency g kg^?1 of the fish groups fed on 30 and 40 g kg^?1 CWC diets showed higher values (P < 0.05) than those of other tested fish groups (0, 10 and 20 g kg^?1 CWC). Apparent digestibility coefficients of protein and dry matter were improved (P < 0.05) in CWC‐tested fish groups compared to the control fish group. These data were powered by the data of the water quality that showed significant (P < 0.05) enhancement in both dissolved oxygen and ammonia concentrations by the increment in dietary charcoal levels. The above‐mentioned parameters' data suggested that 30 g kg^?1 dietary CWC can be considered as a suitable level to maintain normal growth of red tilapia juveniles as well as to enhance water quality of the rearing area.     

The awakening of invertebrates: The daily dynamics of fishes and mobile invertebrates at Rapa Nui's multiple use marine protected area

• 1. On shallow reefs, day-night activity patterns between fishes and invertebrates are presumed to reflect trade-offs between feeding and predation; however, quantitative data on daily community dynamics are scarce. Moreover, night surveys may contribute important information for biodiversity inventories or baselines that normally are not considered.
• 2. This study used standardized day–night visual surveys of fishes and mobile invertebrates on the same transect lines in Rapa Nui (Easter Island) and investigated how diel patterns vary between taxonomic and trophic groups.
• 3. Distinct differences between taxonomic groups were observed, with fishes being more abundant during the day (>twice), whilst invertebrate abundance and richness showed an opposite trend with higher numbers at night (>three times).
• 4. Analysis of trophic groups showed that herbivorous and planktivorous fishes were more abundant during the day. Carnivorous fishes did not show any trends. Top predators (Apex) were observed only at very low abundances. However, a replacement amongst carnivorous fish species between day and night was found, where labridae fishes were practically absent during nights.
• 5. Most of the mobile invertebrates remained concealed during the day, probably due to the influence of predation risk (labrid fishes). The results emphasize the need for consideration of nocturnally active invertebrates in biodiversity inventories or baselines of reefs, which focus heavily only on diurnal surveys.
• 6. Day–night reef surveys should be included in marine protected area planning and monitoring as this provides a better understanding of shallow benthic communities and helps inform proper management decisions.

     

The potential of pet‐grade poultry by‐product meal to replace fish meal in the diet of the juvenile spotted rose snapper Lutjanus guttatus (Steindachner, 1869)

A 12‐week feeding trial was conducted to examine the replacement of fish meal with pet‐grade poultry by‐product meal (PBM‐PG) in the spotted rose snapper Lutjanus guttatus diet. Five experimental diets were formulated to contain graded levels of PBM‐PG at proportion of 250, 500, 75 or 900 g kg^?1. The control diet contained sardine fish meal as the main protein source. Four groups of 15 randomly assigned L. guttatus juveniles were fed to satiation 3 times day^?1. Except for the fish fed the PBM‐PG90 diet, the growth performance, survival and feed utilization efficiency of the experimental fish were not significantly lower than those of the control fish. The dietary level of PBM‐PG did significantly affect the haematological characteristics (P < 0.05). The dietary dry matter and protein apparent digestibility coefficients (ADCs) decreased with increasing dietary PBM‐PG. High values for lipid ADCs were observed in all diets, with significant differences among the dietary treatments. The fish whole‐body protein, moisture, lipid and ash contents were not affected by the inclusion of dietary PBM. These results indicate that high‐quality terrestrial PBM can successfully replace more than half of the marine fish meal protein in the L. guttatus diet.     

Effects of dietary inactivated Pediococcus pentosaceus on growth performance,feed utilization and blood characteristics of red sea bream,Pagrus major juvenile

A feeding trial was carried out to determine effects of dietary supplements of inactivated Pediococcus pentosaceus (PP) on growth, feed utilization and blood characteristics of red sea bream. Five diets containing different concentrations [0 (PP0), 1.6 × 10¹⁰ (PPI), 1.6 × 10¹¹ (PPII), 1.6 × 10¹² (PPIII) and 3.2 × 10¹² (PPIV) cells g^?1] of PP were fed to fish for 56 days. At the end of the feeding trial, the obtained results revealed a significant increase (P < 0.05) in weight gain, specific growth rate and skin mucus secretion in all PP‐supplemented groups when compared with control group. Moreover, fish fed PPIII and PPIV diets resulted in significantly higher final body weight, feed efficiency ratio and bactericidal activity than those of fish fed PP0 diet (P < 0.05). Further, fish fed the PPIII diet also had a higher feed intake, protein efficiency retention, haematocrit, mucus lysozyme activity (LA), plasma and serum proteins than those of PP0 fed group (P < 0.05). Similarly, fish fed PPIV diet resulted in a significant increase in serum LA, peroxidase activity and tolerance against low‐salinity stress test (P < 0.05). Considering these promising results, we suggest that the supplementation of PP Prep improves growth and health conditions of Pagrus major.