Fish Stomach Research Articles

Improvement in spotted rose snapper growth and skin coloration after incorporation of shrimp head meal in diet

Four isonitrogenous (45% crude protein) and isoenergetic (20.29 – 20.47 kJ/g) experimental diets were formulated by replacing 0%, 10%, 20% and 30% of fish meal (FM) with shrimp head meal (SHM) as a source of protein and tested the rearing performance and skin coloration of spotted rose snapper Lutjanus guttatus. The SHM had a high content of protein and pigments (i.e., carotenes and xanthophylls), but also chitin which eventually could be an anti-nutritional constituent in the diet for some fish species. A total of 240 fish (initial average weight of 77 ± 0.5 g) were distributed in 12 fiberglass tanks (3000 L) (20 fish/tank) and were fed twice a day for 70 days. The fish feed diets containing SHM showed the highest growth rates (weight gained, WG; 82.8–88.2 g) and lowest feed conversion ratio values (FCR; 1.3 – 1.4) compared to the D-Control diet (WG; 62.1 g and FCR; 1.5). The chitinolytic enzymatic activity (CEA) significantly increased in the stomach of fish fed diets containing SHM. The fish fed diets containing 20% and 30% of SHM, showed higher redness and more reddish-orange tones than the fish fed with the D-Control diet. The FM replacement had improvements in final growth, chitinolytic enzymatic activity, and skin coloration of spotted rose snapper. Thus, the use of up to 30% SHM protein in practical diets for spotted rose snapper should be a good alternative to develop more efficient aquafeed production for these species, however, further research could be suggested to determine the effectiveness of SHM as a substitute for FM in diets for spotted rose snapper rearing at a commercial scale conditions.

Les romans paléologues et les contes arabes

ABSTRACTThe Palaiologan romances, inspired by courtly romances, align their Western models with the Byzantine literary tradition and draw from more popular patterns, such as a narrative punctuated by meta-enunciative locutions, also employing magical items and ancestral fabulous motifs, such as the flying horse (derived from the tales of One Thousand and One Nights) or the jewel swallowed by a hawk and discovered in a fish's stomach, a motif employed in the Qamar az-Zaman tale of One Thousand and One Nights.

Can you stomach it? Comparative transcriptomics and biochemistry of the stomachs of prickleback fishes (Stichaeidae) consuming different diets

Despite obvious whole animal, tissue level, and biochemical differences among species with different diets, dietary specialization has molecular underpinnings that are not well understood. In this project, we used comparative transcriptomics of stomach tissues to observe how prickleback fishes (Stichaeidae) achieve dietary-driven differences in stomach function. Xiphister mucosus (herbivore), X. atropurpureus (omnivore), Phytichthys chirus (omnivore) and the carnivorous Anoplarchus purpurescens were harvested from the wild, and fed omnivore and/or carnivore diets in the laboratory. Transcriptomes were sequenced for stomach tissues from two individuals per species and diet treatment. The number of shared orthologs varied with phylogenetic relatedness of the species (i.e., sister-taxa X. mucosus and X. atropurpureus shared the most expressed genes among the species), and differential expression and selection analyses are underway, although hydrogen-potassium ATPase appears to be under positive selection in some species. All four fish species strongly expressed pepsinogen and chitinase genes in their stomachs, yet biochemical activity levels (N ≥ 6 per species and diet treatment) of these two digestive enzymes matched natural diet, with the species consuming the most protein ( A. purpurescens) and chitin ( P. chirus) having the highest pepsin and chitinase activities, respectively. These activities were relatively unaltered by the laboratory diets, suggesting that activity level cannot be changed significantly through a dietary shift. Although intestinal carbohydrases typically show support for the Adaptive Modulation Hypothesis—a match among digestive enzyme activities with concentrations of ingested substrate—this may be one of the first investigations to observe such support for gastric enzymes. Thus, beyond being an important vertebrate innovation, the stomach may also provide digestive benefit depending on natural diet. NSF Grant IOS-1355224 and NSF DBI-1852096 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effectiveness of fish assemblage as seed dispersers in Amazon oligotrophic flooded forests

AbstractIn tropical and highly diverse systems, Seed Dispersal Effectiveness (SDE) is a very useful approach to investigating the role of seed dispersers in one of the most important and complex phases of plants by analysing the quantitative (QC) and qualitative (QL) components of the seed dispersal process. Although fishes are recognized as an important guild of frugivores in flooded environments, we still know very little about the dispersal effectiveness performed by this group. Our study evaluated two quantitative subcomponents of effectiveness, where we used: (a) the volume of intact and crushed seeds found in the stomach and intestine of fish (QC1), and (b) the total number of tested and viable seeds (QC2). From these subcomponents, a two‐dimensional landscape of effectiveness was generated and a fish species was ranked according to the quantitative component of the SDE. Eight species of fish consumed 1054 seeds belonging to 16 plant species. Sphinctanthus striiflorus, Corynostylis pubescens, Connarus sp. and Piper sp., were the most abundant plant species in fish's diets, totalling 95% (N = 983) of the seeds consumed. We used a tetrazolium viability test protocol and about 678 (85%) of the 797 seeds tested were viable and 119 (14.7%) were unviable; the viability test was inconclusive for less than 1% of the seeds. Our findings showed that, as seen in other effectiveness studies with terrestrial vertebrate dispersers, fish species also have different degrees of effectiveness. Additionally, we pointed out that the fish species more specialized in the consumption of fruits and seeds were quantitatively more effective dispersers, while species with lower SDE corresponded to generalists that just occasionally consume seeds. We suggest that high‐diversity fish assemblages allow for greater complementarity in the seed dispersal interaction, which can potentially favour the recruitment of plant species via ichthyochory.

Isolation and identification of a new strain Micropterus salmoides rhabdovirus (MSRV) from largemouth bass Micropterus salmoides in China

As an important farmed fish worldwide, largemouth bass (Micropterus salmoides) is suffering a severely disease caused by rhabdovirus, which has resulted to a massive economic loss. In the present study, a new Micropterus salmoides rhabdovirus (MSRV) strain named MSRV-NY01 was isolated from largemouth bass juvenile from a fish farm in Nanyang, Henan province, China. Cell culture, histopathological examination, reverse transcription-polymerase chain reaction (RT-PCR), plaque purification, phylogenetic analysis, transmission electron micrograph (TEM) observation, experimental infection, real-time quantitative polymerase chain reaction (RT-qPCR) were used for virus isolation and identification. The diseased fish exhibited abnormal symptoms with anorexia, exophthalmia, bloated abdomen, spiral swimming, hemorrhage on body surfaces, and fluid accumulation in the abdominal cavity. Histopathological examination showed obvious hemorrhage, inflammatory cell infiltration, and widespread cell degeneration and necrosis were presented in the liver, spleen, intestine and stomach of diseased fish. Obvious cytopathic effects (CPE) were induced in epithelioma papillosum cyprini (EPC), grouper spleen (GS) and grouper fin (GF-1) cell lines after inoculation of mixed liver and kidney homogenates from disease fish. RT-PCR, DNA sequencing and phylogenetic tree analysis showed that the virus belongs to rhabdovirus with the highest similar to the MSRV-FJ985 strain. Through five sequential rounds of plaque purification assay, a MSRV plaque isolate was derived and was confirmed by RT-PCR and DNA sequencing. TEM observation showed that numerous virions with typical bullet shape (100–150 nm in length and 70–90 nm in diameter) were present in infected GS cells. Thus, this newly isolated virus from diseased Micropterus salmoides was tentatively named as MSRV-NY01. Regression infection experiment indicated that MSRV-NY01 was highly pathogenic to Micropterus salmoides juvenile and the cumulative mortality of fish injected with 5 × 104, 104, 2 × 103, 4 × 102, 2 × 102, 102 and 50 PFU of virus were 100%, 100%, 100%, 96.7%, 96.7%, 93.3% and 90%, respectively. Moreover, RT-qPCR showed that MSRV was present in all 9 tested tissues of infected fish, and the virus loads of the spleen and heart were significantly higher than that in other tissues tested. In conclusion, we isolated and identified a new MSRV strain from diseased largemouth bass, and our results will provide new material and information for the prevention and control strategy for MSRV.

Microplastic Accumulation in Catfish and Its Effects on Fish Eggs from Songkhla Lagoon, Thailand

Microplastics have been found to accumulate in freshwater, marine ecosystems, and biological organisms. The frequency of studies on microplastic contamination in organs has increased recently, although there have been relatively fewer investigations on fish eggs in Thailand. To extract microplastics from catfish samples for laboratory analysis (Osteogeneiosus militaris), we used 10% potassium hydroxide in the digestion process. A needle penetrated the fish eggs to investigate microplastic contamination. We examined microplastics under a stereomicroscope and used Fourier transform infrared spectroscopy to determine the type of polymer. We found microplastic contamination in organs, most commonly in the stomach (0.91 ± 0.13 items/g), followed by tissue (0.53 ± 0.09 items/g), and gills (0.30 ± 0.03 items/g) at the level of significance p < 0.01. We found a total of 349 fish eggs with 27 items of microplastic. The dominant microplastic we found in the stomach, tissue, and gills of the fish, as well as in fish eggs, was of fiber shape. We noted that fragments were found only in the stomach and tissue of fish. The dominant color of microplastics was black in organs and blue in fish eggs. The common polymer types in organs and fish eggs were polyethylene terephthalate, polypropylene, and cellulosic fiber.

Feeding ecology of Benthosema glaciale across the North Atlantic

The glacier lanternfish Benthosema glaciale is a key myctophid with a wide distribution in the northern Atlantic. It is a species that has a strong vertical migration capacity and have the potential to move between the surface waters and mesopelagic depths in a diel cycle (DVM), mainly depending on ambient light conditions. We investigated the feeding ecology of B. glaciale across the Norwegian, Iceland, Irminger and Labrador Sea basins. An important component of Benthosema diet was various types of calanoid copepods, but with some additional variability across the deep basins. ‘House’s’ of Appendicularia were only found in stomachs from the Labrador basin and were positively selected for here. The large calanoid Calanus hyperboreus was strongly selected for in the Iceland Sea, while its smaller counterpart C. finmarchicus was negatively selected for here. Fish from the Irminger, Labrador and Norwegian Seas displayed a high number of empty stomachs while no fish stomachs were found empty in the Iceland Sea. Contrary to expectation due to being located at the highest latitude, Benthosema in the Iceland Sea had significantly higher condition factor (for both small and large fish) and liver indices compared to fish from other basins, but the abundance of small fish in the sampled population here was very low. This contrasts with the “light environment exclusion” (LEE) hypothesis, which propose that the extreme light environment at higher latitudes restricts feeding opportunities for mesopelagic fish at high latitudes. It is suggested that improved classification of prey through stomach analyses should aim to allow bioluminescent organisms to be separated from non-bioluminescent prey if feasible. This would allow improved resolution to analyse stomach contents and certainly progress our understanding of the success of myctophids across variable habitats.

Comparative study of algal community in African sharptooth catfish (Clarias gariepinus, Burchell 1822) and Nile tilapia (Oreochromis niloticus, Linnaeus 1758) farming ponds

AbstractIn subsistence and small‐scale fish farming, algae are an important food source for fish. Therefore, understanding their distribution and diversity in fish ponds is essential. This study aimed at characterising algae species in African sharptooth catfish (Clarias gariepinus) and Nile tilapia (Oreochromis niloticus) farming ponds and their contribution to these species’ diet. Water samples were collected from different points of the farming pond: in rearing pond, evacuation canal of each species and decantation pond. Samples were also collected from fish stomachs and intestines. Afterwards, they were analysed with a photonic microscope for species identification using standard identification keys. The highest species richness (S) and Shannon index (H) were observed in fish rearing ponds (S = 73, H = 2.98–3.84) and the lowest in fish stomachs and intestines (S = 41, H = 1.88‐3.07). Jaccard's similarity index, ranging from 0.17 to 0.55, shows a high specific diversity of alga in the different sampling points. During the experimental period, water physicochemical parameters were within the optimum growth for algae and fish species. Since some algae species recorded are consumed by both fish species, this study recommends to select and cultivate them for fish food production.

Fish-mediated nutrient flows from macroalgae habitats to coral reefs in the Red Sea

Macroalgae canopies are common in tropical coastlines, and can be feeding grounds for coral reef fishes. We investigated whether fish transfer algal material from Sargassum-dominated macroalgae habitats to coral reefs by collecting gut contents of two herbivorous fish species (Naso elegans and N. unicornis) from coral reefs in the central Red Sea. On inshore reefs close to macroalgae canopies, Sargassum accounted for up to 41% of these species’ gut contents while almost no Sargassum was found in the stomachs of fish on offshore reefs farther from macroalgae canopies. Using consumption and excretion rates from literature, we estimate that these fish consume up to 6.0 mmol C/m2 reef/day and excrete up to 10.8 μmol N/m2 reef/day and 1.0 μmol P/m2 reef/day across inshore reefs as a result of Sargassum consumption. Examining fish-mediated connections between habitats illuminates the role of fish as a vector of nutrition to nutrient-poor coral reefs.

Quantifying diets for small pelagic fish: effects of weight versus occurrence methods and sampling effort

AbstractIn the Norwegian Sea, assessment of diet composition relies on annual cruise activity combined with visual identification and weight determination of prey from fish stomachs. This weight-based method is labour intensive, and suggestions to reduce cost include moving from the weight-based to the occurrence-based method and/or reducing sampling effort. Studies have suggested that the occurrence-based method may be more robust while providing similar results as the weight-based method. Here we re-analyse data from >14.000 stomachs for herring, mackerel, and blue whiting. We compare diet composition estimates and quantify the uncertainty using both methods. We also quantify the impact of reducing sampling effort (number of trawl stations and fish per station) on the diet uncertainties. Our results confirm that occurrence-based estimates are more precise than those based on weight. In addition, they are better at capturing year-to-year fluctuations. The occurrence-based method provides similar results to the weight-based method. Differences between methods arise primarily from disparities in the mean weight of prey in stomachs. Decreasing the number of stations sampled leads to increased uncertainty, while reducing the sampling effort from 10 to 5 fish per station has little impact on uncertainty estimates. These results provide quantified insights to guide future diet monitoring programmes.

Plant-based polymer as a thermoresistant carrier of phytase in Nile tilapia (Oreochromis niloticus) diets

A biodegradable soybean oil-based polymer produced following the Green Chemistry principles, was assessed as a thermoresistant vehicle of phytase aiming to improve the enzyme stability during fish diet processing. Juvenile Nile tilapia (70 ± 4.3 g) were submitted to a digestibility assay designed in a factorial model (3 ×2) to assess the polymer efficiency. The treatments comprised the combination of three phytase inclusion methods with two feed processing methods. The inclusion methods of phytase were: CPP- coating post processing, in which the enzyme was spread on top of pellets after processing, PAE- polymer associated to enzyme, which was adsorbed by the polymer and included in the ingredients mash prior feed processing and NE- no enzyme inclusion, playing a control role as phytase was not included. The feed processing methods were extrusion (120 °C) or pelleting (40 °C), exposing the polymer to different temperatures. Phytase was supplemented at 1500 units kg−1 using the CPP or PAE methods. There was a significant interaction for the apparent digestibility coefficient (ADC) values of phosphorus (P), calcium (Ca) and Ash (P < 0.05). CPP resulted in higher ADC values for P and Ca, compared to PAE and NE in extruded diets (P < 0.05). The PAE method resulted in higher ADC values of P, Ca, and Ash than NE in extruded diets (P < 0.05). In pelleted diets, PAE resulted in higher ADC values for P and Ca, and a similar ADCAsh in comparison to CPP (P < 0.05). As verified in extruded diets data, the polymer partially protected phytase from heat denaturation, resulting in higher ADC values in comparison to NE (P < 0.05). The polymer improved phytase effects in pelleted diets probably by reducing degradation in fish stomach. These results suggest that the polymer may be a potential protective carrier of phytase and other thermolabile additives in extruded and pelleted diets.

Dietary selenium regulates the diversity and stability of microbial communities in stomach and intestine of rabbitfish (Siganus oramin)

The stability of gastrointestinal ecosystem and microbial interactions herein are critical to host health, but how to regulate gut microbiota and maintain its stability remains unclear. Macroalgae used as fish feed has economic and environmental advantages, and an extra addition of selenium (Se) may further replenish the necessary micronutrient for fish. Recent studies suggested that dietary Se could enhance fish health by regulating Se-associated enzymes. However, the effects of dietary Se on the microbial diversity and stability in fish stomach and intestine are poorly understood. Rabbitfish (Siganus oramin) fed with different contents of dietary Se enriched in macroalgae were used to investigate the effects of Se on the fish growth and gastrointestinal microbial communities. We found that the low dietary Se (∼2.51 μg/(g·dw)) could significantly enhance the growth of rabbitfish and maintain gastrointestinal ecological stability. The microbial ecological networks indicated that the low dietary Se altered the potential interactions within microbial community and increased the number of potential keystones to maintain the stability. Moreover, low dietary Se improved the microbial diversity, enhanced probiotics but reduced pathogenic bacteria in the gastrointestinal ecosystem. We also found that the microbiota in stomach was more diverse and stable than that of intestinal microbiota under the enriched Se diets. This study reveals the effects of dietary Se on fish growth and the underlying mechanism maintaining network stability in gastrointestinal ecosystem, which also broadens our understanding of dietary regulation of gastrointestinal microbiota.

FEEDING HABITS OF SOLDIER CROAKER Dendrophysa russelii (Cuvier, 1829) DISTRIBUTED IN COASTAL AREAS OF THE MEKONG DELTA, VIETNAM

This study researched the feeding habits of soldier croaker Dendrophysa russelii (Cuvier,1829) distributed in coastal areas of the Mekong Delta from May to December, 2021. Fish samples were randomly collected in different sizes by trawl-net. Fish stomachs were fixed in a 4% formalin solution to prevent contents in the stomach from being digested. The results showed that soldier croaker had a small mouth, the teeth on the jaw were short and pointed with no canine tooth, the gill rakers were sparse, the stomach was pouch-shaped, the caeca have 4-8 tubes, and the intestine was short. Relative between gut length and body length (RLG) &lt; 1 indicated that soldier croaker is a carnivorous fish. The food spectrum of immature fish was narrower thanthat of mature fish. However, the feed ingredient was shrimp which always accounts for the highestpercentage in the two fish size groups, followed by fish and other foods that accounted for a low proportion.

Preliminary results on feeding habits of the invasive fish Fistularia commersonii (Ruppell, 1862) in the coast of Benghazi, Libya

The feeding habits of the exotic fish Fistularia commersonii off the coast of Benghazi, Libya were investigated. A total of 189 specimens were collected throughout the year of 2012-2013. The mean total length (TL) and mean weight was 99.08±6.45cm and 545.33±116 g, respectively. The condition factor (K) ranged between 0.7 and 0.8. Fish were found in large quantities (87%) in the stomach of the blue-spotted cornet fish. While crustaceans (2%) and mollusks (1%). The results showed also that F. commersonii feeds on prey from diverse habitats as well as depths.

The Sidney Sperry/Heber Snell Debates: Critical Biblical Scholarship and Mormon Tradition

The Sidney Sperry/Heber Snell Debates: Critical Biblical Scholarship and Mormon Tradition

Identification and Quantification of Microplastics in the Marine Environment Using the Laser Direct Infrared (LDIR) Technique.

Here, we evaluate for the first time the performances of the newly developed laser direct infrared (LDIR) technique and propose an optimization of the initial protocol for marine microplastics (MPs) analysis. Our results show that an 8 μm porosity polycarbonate filter placed on a Kevley slide enables preconcentration and efficient quantification of MPs, as well as polymer and size determination of reference plastic pellets of polypropylene (PP), polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET), with recoveries ranging from 80-100% and negligible blank values for particle sizes ranging from 200 to 500 μm. A spiked experiment using seawater, sediment, mussels, and fish stomach samples showed that the method responded linearly with significant slopes (R2 ranging from 0.93-1.0; p < 0.001, p < 0.01). Overall, 11 polymer types were identified with limited handling and an analysis time of ca. 3 h for most samples and 6 h for complex samples. Application of this technique to Mediterranean marine samples (seawater, sediment, fish stomachs and mussels) indicated MP concentrations and size distribution consistent with the literature. A high predominance of PVC (sediment, fish stomachs) and PE and PP (seawater, mussels) was observed in the analyzed samples.

Dynamics of plankton populations as natural food for fish in a tributary of the Ogan River

The research was conducted to determine the abundance, diversity, uniformity, and dominance of plankton in fish stomachs and waters that are expected to provide information about water productivity. The research was carried out in a tributary of the Ogan River, Indralaya District, Ogan Ilir Regency, South Sumatra at three stations, namely Indralaya Mulya Village, Tanjung Seteko Village and Muara Penimbung Village. The method used field surveys and location determination using purposive sampling with fish stomach contents, water samples for plankton observations, and water quality parameters. Fish sampling was carried out six times in 3 months, and water samples for plankton observations were one time per month, from April to June 2018. Plankton is found in fish stomachs and waters with a total abundance of 35.6 - 448.12 ind/l plankton consisting of 8 divisions with 11 classes. The plankton diversity index has moderate diversity and moderate community stability with a value between 1.11 - 1.45. The uniformity index of plankton in the fish stomach showed small uniformity of plankton (0.41-0.67), while in the waters, at station three and station 1 in April, the uniformity was high (E values 0.72 and E 0.93). The value of the plankton dominance index is in the range of 0.27-0.37. No species dominate other species or D = 0 (0.5), with moderately polluted water quality

Identification of Microplastics in Common Carp (Cyprinus carpio) at Koto Panjang Reservoir Kampar Regency Riau Province

In the Koto Panjang Reservoir the microplastic may originated from the degraded plastic waste as well as degraded plastic net from the fish culturing cages. The microplastic may be accidentally ingulfed as fish swallowing their food. To understand the present of microplastic present in the stomach of wild common carps living around the fish net cage, a study was conducted on in December 2020- February 2021. The fish were captured using fish net (3-5 inc mesh size), 3 times, once/ 2 weeks. The fish stomach was removed and the presence of the microplastic was identified. The stomach content of the fish was mixed with 10% KOH (minimum 3 x of stomach content volume) and was incubated for2 weeks to dilute the organic materials. Then the presence of microplastic was observed using a binocular microscope. Types and abundance of the microplastic was noted. Results shown that the types of microplastic present were films, fibers and fragments. The highest type of microplastic found in the stomach of the fish was films (2.3 particles/ fish), followed by fibers (0.6 particles/fish) and fragments (1.1 particles/ fish).

Microplastic Identification of Tinfoil Barb (Puntius schawanafeldii) in Koto Panjang Dam Kampar Regency Riau Province

Plastic waste can be found everywhere, including in the Koto Panjang Dam. As the plastic waste degraded, the microplastic materials may be distributed in the water and it may be accidentally swallowed by omnivorous fishes such as Puntius schawanafeldii. To understand the presence of the microplastic materials in the fish stomach, a research has been conducted in December 2020 - February 2021. The number of P. schawanafeldii captured was 30 using fish net in 3-5 inch mesh size. The fish was dissected and the stomach was removed. Then the stomach content was added with 10% KOH andwas incubated for 2 weeks to delute the organic materials. Then was investigated under a binocular microscope to find out the microplastic materials. Results shown the type of microplastic present in the stomach of P. schawanafeldiiwas namely film, fibre, and fragment. The most common type of microplastic found was film, followed by fragments and fibre. The abundance of microplastic in the stomach of P. schwanafeldii was around 2 – 15,8 particles/fish

Captive Rearing of Longfin Smelt Spirinchus thaleichthys: First Attempt of Weaning Cultured Juveniles to Dry Feed.

Simple SummaryLongfin smelt Spirinchus thaleichthys is an imperiled estuarine species in California, USA. A captive culture program is currently being developed; however, prior to this study, longfin smelt have only fed on live prey in the hatchery. Here, we report on our first successful attempt to wean cultured juveniles onto a dry commercial pellet feed. A subset of F1 fish was switched to a mixed diet of reduced Artemia and dry feed for 62 days, with growth, survival, and body condition compared between feeding treatments. Our results highlight that juvenile longfin smelt can utilize dry feeds while maintaining a healthy body condition.The rapid decline of longfin smelt Spirinchus thaleichthys, a threatened euryhaline forage fish in California, is a serious concern for scientists and resource managers. To recover and conserve this species, a captive culture program was initiated, focusing on the collection, captive rearing and breeding of wild broodstock, and the rearing of their offspring. Although progress has been made in the collection of broodstock and the production and culturing of larvae, no studies have evaluated the rearing of juvenile life stages in captivity. The present study examines methodological considerations for culturing F1 juvenile longfin smelt, specifically, the first efforts toward weaning juveniles to a dry commercial pellet feed. Cultured juvenile longfin smelt were fed live Artemia only or co-fed Artemia and dry feed for 62 days, and the effects of feed type on juvenile survival, growth, body condition, and fatty acid profiles were examined. No significant differences were observed between feeding treatments, despite an 80% reduction in Artemia in the co-feeding treatment. Furthermore, examination of fish stomach contents at the end of the trial confirmed the transition to dry feed. This is the first study to indicate successful feeding by longfin smelt on dry commercial pellets, and suggests that juvenile longfin smelt can be fully weaned onto dry feeds. Results of this study are critical for closing the lifecycle of longfin smelt in captivity and developing a successful conservation culture program for this imperiled species.