Fish Skin Research Articles

Isolation and Characterization of Collagen and Collagen Peptides with Hyaluronidase Inhibition Activity Derived from the Skin of Marlin (Istiophoridae).

Type I and V collagens are the major components of fibrillogenic proteins in fish skin, and their hydrolysis products possess hyaluronidase inhibitory activity. In this study, for the first time, type I and V collagens were isolated from the skin of shortbill spearfish and striped marlin. Type I (2α1[I]α2[I]) and type V (α1[V]α3[V]α2[V]) collagens composed of distinct α-peptide chains with comparable structures were investigated using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and UV spectrophotometric chromatography. After enzymatic digestion, the collagen peptides were purified by using ultrafiltration (30 KDa) and high-performance liquid chromatography (RP-HPLC) to yield CPI-F3 and CPV-F4 fractions with strong hyaluronidase inhibition rates (42.17% and 30.09%, respectively). Based on the results of simulated gastrointestinal fluid, temperature, and pH stability assays, CPI-F3 and CPV-F4 exhibited stability in gastric fluid and showed no significant changes under the temperature range from 50 to 70 °C (p > 0.05). The results of this first research on the bioactivity of type V collagen peptides provide valuable information for the biomedical industry and show the potential for future bioactivity investigations of type V collagen and its peptides.

Unique structures and material properties of the skin in different body regions of three species of fish.

Benefitting from its unique helically arranged fiber structures, fish skin is a superior biological protective tissue. Reported here is a study of the microscopic morphological characteristics and mechanical properties of the skin of three species of fish, that is, Taihu white fish (Erythroculter ilishaeformis), grouper (Cichlasoma managuense), and yellowfin seabream (Ditrema temminckii Bleeker), revealing the special protective mechanisms of fish skin. Experiments involving scanning electron microscopy show that the stratum compactum is the main part of fish skin and comprises helically stacked fibers, with the helical ply angles of the fibrous layers differing significantly for the different fish species and in different regions of their bodies. Tension and penetration experiments show that fish skin provides a fish's body with considerable mechanical protection from lacerations and bites inflicted by its natural enemies. Moreover, the mechanical tests show that fish skin has two different defensive mechanisms against tension and penetration loads, thereby offering a novel idea for designing body armor that is both flexible and tough.

Construction of benzyl isothiocyanate-loaded fish skin gelatin-luteolin compound emulsion delivery system, and its digestion and absorption characteristics.

Fish skin gelatin (FSG) and luteolin (LUT) were used as composite emulsifiers, and benzyl isothiocyanate (BITC) was used as a model of nutrient delivery to construct a stable emulsion. The storage stability of the FSG-LUT emulsion and its effect on BITC release were investigated both in vitro and ex vivo. LUT can quench FSG fluorophores statically and form a stable complex through hydrogen bonding and hydrophobic interactions. The FSG-LUT emulsion storage stability and embedding rate were higher than those of the FSG emulsion. The FSG-LUT emulsion microstructure was resistant to oral and gastric digestion, and the BITC retention rate and bioaccessibility were much higher than those of the FSG emulsion. Lastly, the ex vivo everted gut sac of rat intestine study demonstrated that BITC showed the highest absorption in the ileum, and the FSG-LUT emulsion absorbed BITC and sustained a controlled release in a specific position. LUT could form stable complexes with FSG, which improved the stability and bioavailability of BITC in the FSG-LUT emulsion delivery system, and promoted further intestinal BITC absorption. © 2022 Society of Chemical Industry.

Synthesis, modification and application of fish skin gelatin-based hydrogel as sustainable and versatile bioresource of antidiabetic peptide

Gelatin hydrogel is widely employed in various fields, however, commercially available gelatin hydrogels are mostly derived from mammalian which has many disadvantages due to the supply and ethical issues. In this study, the properties of hydrogels from fish-derived collagen fabricated with varying Glutaraldehyde (GA) determined. The antidiabetic properties of salmon gelatin (SG) and tilapia gelatin (TG) was also evaluated against α-glucosidase. Glutaraldehyde-crosslinked salmon gelatin and tilapia gelatin were used, and compared with different concentrations of GA by 0.05 %, 0.1 %, and 0.15 %. Water absorbency, swelling, porosity, pore size and water retention of the hydrogels were dependent on the degree of crosslinking. The synthesis of hydrogels was confirmed by FTIR study. Scanning electron microscope (SEM) observation showed that all hydrogels have a porous structure with irregular shapes and heterogeneous morphology. Performance tests showed that gelatin-GA 0.05 % mixture had the best performance. Antidiabetic bioactivity in vitro and in silico tests showed that the active peptides of SG and TG showed a high binding affinity to α-glucosidase enzyme. In conclusion, SG and TG cross-linked GA 0.05 % have the potential as an antidiabetic agent and as a useful option over mammalian-derived gelatin.

Marine vampires: Persistent, internal associations between bacteria and blood-feeding marine annelids and crustaceans.

Persistent bacterial presence is believed to play an important role in host adaptation to specific niches that would otherwise be unavailable, including the exclusive consumption of blood by invertebrate parasites. Nearly all blood-feeding animals examined so far host internal bacterial symbionts that aid in some essential aspect of their nutrition. Obligate blood-feeding (OBF) invertebrates exist in the oceans, yet symbiotic associations between them and beneficial bacteria have not yet been explored. This study describes the microbiome of 6 phylogenetically-diverse species of marine obligate blood-feeders, including leeches (both fish and elasmobranch specialists; e.g., Pterobdella, Ostreobdella, and Branchellion), isopods (e.g., Elthusa and Nerocila), and a copepod (e.g., Lernanthropus). Amplicon sequencing analysis revealed the blood-feeding invertebrate microbiomes to be low in diversity, compared to host fish skin surfaces, seawater, and non-blood-feeding relatives, and dominated by only a few bacterial genera, including Vibrio (100% prevalence and comprising 39%-81% of the average total recovered 16S rRNA gene sequences per OBF taxa). Vibrio cells were localized to the digestive lumen in and among the blood meal for all taxa examined via fluorescence microscopy. For Elthusa and Branchellion, Vibrio cells also appeared intracellularly within possible hemocytes, suggesting an interaction with the immune system. Additionally, Vibrio cultivated from four of the obligate blood-feeding marine taxa matched the dominant amplicons recovered, and all but one was able to effectively lyse vertebrate blood cells. Bacteria from 2 additional phyla and 3 families were also regularly recovered, albeit in much lower abundances, including members of the Oceanospirillaceae, Flavobacteriacea, Porticoccaceae, and unidentified members of the gamma-and betaproteobacteria, depending on the invertebrate host. For the leech Pterobdella, the Oceanospirillaceae were also detected in the esophageal diverticula. For two crustacean taxa, Elthusa and Lernanthropus, the microbial communities associated with brooded eggs were very similar to the adults, indicating possible direct transmission. Virtually nothing is known about the influence of internal bacteria on the success of marine blood-feeders, but this evidence suggests their regular presence in marine parasites from several prominent groups.

Killing effect of fish serum and mucus on Gyrodactylus cichlidarum (Platyhelminthes, Monogenea) mediated by complement

Gyrodactylids mainly parasitizing on the skin and fins of fishes, represent an ongoing challenge of farmed fishes. Evidences from previous studies suggested that complement system play important role in fish against gyrodactylids. Through a series of parasite killing experiments with fish sera and mucus, the present study revealed the role of Oreochromis niloticus complement in killing Gyrodactylus cichlidarum. The killing effect on G. cichlidarum was observed in serum and mucus of O. niloticus, which was markedly weakened after the complement inhibition by heat treatment and C3 antibody neutralization. Scanning electron microscopy (SEM) revealed various injuries on the tegument of G. cichlidarum exposed to O. niloticus serum. After inhibiting the alternative complement pathway (ACP) by zymosan, the killing activity of O. niloticus serum to G. cichlidarum was significantly attenuated (P < 0.01). The inhibition (by adding EGTA or l-lysine) to the classical complement activation pathway (CCP) also resulted a weak suppression on the killing effect. The results demonstrated the indispensable role of O. niloticus complement in killing G. cichlidarum, mainly via the ACP and with the involvement of CCP as well. In addition, complement in serum of an unnatural host (Ctenopharyngodon idella) of G. cichlidarum showed highly significantly weaker killing effect to G. cichlidarum than that of O. niloticus (P < 0.01), which needs further study for its mechanism. These findings provided new evidences about the immune mechanism of fish against gyrodactylids, and are reference for the study on the control of gyrodactyliasis.

Quality of DNA extracted from freshwater fish scales and mucus and its application in genetic diversity studies of Perca fluviatilis and Rutilus rutilus.

Studies on genetic diversity require biological material containing a reliable source of DNA that can be extracted and analyzed. Recently, non-invasive sampling has become a preferred sampling method of biological material. The suitability of a less invasive approach that involves obtaining samples by swabbing the fish skin (including live, non-anesthetized fish) should be considered. In this study, we compared the efficiency of DNA extraction, amplification, and sequencing of mtDNA fragments of two fish species Perca fluviatilis and Rutilus rutilus based on DNA collected from the scales and mucus using the modified Aljanabi and Martinez method. The results revealed a higher quality of DNA extracted from the mucus; however, the mean DNA concentration obtained from the scales of both fish species was higher. We verified the method suitable for amplification and sequencing of mtDNA fragments of both fish species using newly designed markers (D-loop, ATP6) and examined the potential risk of intraspecific cross-contamination. The DNA sequence alignment analysis revealed identical sequences attributed to the same individual when DNA, extracted from two different sources (scales and mucus), was used. We demonstrated that the quantity and quality of DNA extracted from the scales and mucus using the proposed method were high enough to carry out genetic diversity studies based on sampling of live fish with the possibility to release it after collecting samples.

Development of Composite Edible Coating from Gelatin-Pectin Incorporated Garlic Essential Oil on Physicochemical Characteristics of Red Chili (Capsicum annnum L.)

Red chili is a climacteric fruit that still undergoes respiration after harvest. During storage, it is susceptible to mechanical, physical, and physiological damage and decay incidence, therefore a method is needed to protect it so that the quality losses can be minimized. One way this can be achieved is by applying edible coatings that can be made from hydrocolloids, lipids, or composites of both, in addition to antimicrobial agents that can also be added to inhibit microbial growth. In this study, we detail the application of an edible coating made of gelatin composite from tilapia fish skin, which has a transparent color and good barrier properties against O2, CO2, and lipids. To increase its physicochemical and functional qualities, it must be modified by adding composite elements such as pectin as well as hydrophobic ingredients such as garlic essential oil. This study was conducted to determine the effect of a gelatin-pectin composite edible coating (75:25, 50:50, 25:75), which was incorporated with garlic essential oil (2% and 3%) on the physicochemical properties of red chili at room temperature (±29 °C), RH ± 69%) for 14 days. The best treatment was the 50-50% pectin-gelatin composite, which was incorporated with garlic essential oil with a concentration of 2 and 3%. This treatment provided a protective effect against changes in several physicochemical properties: inhibiting weight loss of 36.36 and 37.03%, softening of texture by 0.547 and 0.539 kg/84 mm2, maintaining acidity of 0.0087 and 0.0081%, maintaining vitamin C content of 2.237 and 2.349 mg/gr, anti-oxidant activity (IC50) 546.587 and 524.907; it also provided a protective effect on chili colors changing to red, and retains better total dissolved solid values.

Formation of hierarchical assemblies by collagen peptides derived from fish skin and bladder and their subsequent application as antiperoxide agents in lipid-rich food.

This study attempts to identify the significant role played by the secondary and tertiary structure of collagen-derived peptides that are involved in lipid peroxide quenching in food products. Fish collagen hydrolysate (CH) was extracted with an efficiency of 70%. The constituent peptides of CH (8.2-9.7kDa) existed in a polyproline-II (PP-II) conformation and at a minimum concentration of 1mgml-1 and pH range 7 to 8, assembled into a stable, hierarchical, quasi-fibrillar (QF) network. The peroxide quenching activity of this QF-CH increased with increasing ionic stability of the assembly and decreased upon proteolytic dismantling. Upon being used as an additive, the QF-CH reduced peroxide formation by 84.5% to 98.9% in both plant and fish-based oil and increased the shelf life of soya oil by a factor of 5 after 6months of storage. The addition of QF-CH to cultured cells quenched peroxide ions generated in situ and decreased stressor activity by a factor of 12.16 abundant peptides were identified from the CH. The reason behind the high efficacy displayed by CH was attributed to its unique charge distribution, prevalence of proton-donating amino acid residues and proximal charge delocalization by the QF network, making fish derived CH a suitable substitute for antiperoxide agents in lipid-rich food.

SpPdp11 Administration in Diet Modified the Transcriptomic Response and Its Microbiota Associated in Mechanically Induced Wound Sparus aurata Skin.

Skin lesions are a frequent fact associated with intensive conditions affecting farmed fish. Knowing that the use of probiotics can improve fish skin health, SpPdp11 dietary administration has demonstrated beneficial effects for farmed fish, so its potential on the skin needs to be studied more deeply. The wounded specimens that received the diet with SpPdp11 showed a decrease in the abundance of Enterobacteriaceae, Photobacterium and Achromobacter related to bacterial biofilm formation, as well as the overexpression of genes involved in signaling mechanisms (itpr3), cell migration and differentiation (panxa, ttbk1a, smpd3, vamp5); and repression of genes related to cell proliferation (vstm4a, areg), consistent with a more efficient skin healing processes than that observed in the wounded control group. In addition, among the groups of damaged skin with different diets, Achromobacter, f_Ruminococcaceae, p_Bacteroidetes, Fluviicola and Flavobacterium genera with significant differences showed positive correlations with genes related to cell migration and negative correlations with inflammation and cell proliferation and may be the target of future studies.

Valorization of emperor fish (Lethrinus lentjan) skin for collagen isolation: effect of acetic acid ratio and extraction time

About 30% of all the proteins in an animal’s body are found in the extracellular matrix, the major consisting of collagen. Industries that process emperor fish (Lethrinus lentjan) produce fish skin that can be utilized to produce collagen sustainably. The objective of this research is to determine the effect of various ratios acetic acid to fish skin and extraction times on the characteristics of collagen. Collagen from the skin of emperor fish was extracted and treated first. For the pretreatment, the skin was immersed in 0.1 M NaOH tenfold (w/v) and replaced after 2 hours for 24 hours at 4 °C. The soaking solution’s proteins, amino acids, and lipid content were all examined. A pre-treated sample was extracted in 0.5 M acetic acid for 24, 36, and 48 hours at 4°C in ratios of 1:10, 1:20, and 1:30. (w:v). The optimum treatment involved extracting for 48 hours at 1:30 (w/v) in acetic acid. The extracted collagen has a yield of 7.70±35% and a whiteness value of 66.76±0.2. The primary amino acids were glycine, proline, and alanine, according to the peptide patterns of the collagen from the skin of emperor fish, which showed α1 and α2 chains with molecular weights of 150-177 kDa. Additionally, this collagen was type 1, and its FTIR spectra and protein pattern were comparable.

Assessment of collagen content in fish skin - development of a flow analysis method for hydroxyproline determination.

This work describes the development of a flow injection method to determine hydroxyproline (HYP), one of collagen's most abundant amino acids. Collagen is a protein with several applications and high nutritional value. Evaluating the feasibility of using collagen from fish skin over its mammalian source is essential. The determination of HYP requires the pre-treatment and hydrolysis of the fish skin to break down collagen into its amino acids, and the HYP value quantified relates to the collagen content. The determination was based on the HYP oxidation with permanganate in an alkaline medium and the consequent decrease of colour intensity registered. Under optimal conditions, the developed method enables the determination of the HYP within the dynamic range of 23.8 to 500 mg L-1, with a limit of detection (LOD) of 2.6 mg L-1 and a limit of quantification (LOQ) of 23.8 mg L-1. Different samples were processed, and the digests were analysed by the proposed method and with the conventional procedure with good correlation (relative error < 7%). Moreover, the analyte quantification is performed faster, simpler, and more accurately, with less toxic solutions. The reproducibility of the developed method was also evaluated by calculating the relative standard deviation of the calibration curve slope (RSD < 1%).

Characterization and functional analysis of pax3 in body color transition of polychromatic Midas cichlids (Amphilophus citrinellus).

As the representative genetic and economic trait of ornamental fish, skin color has a strong impact on speciation and adaptation. However, the genetic basis of skin color pigmentation, differentiation and change is still not understood. The Midas cichlid fish with three typical body color transition stages of "black-gray‑gold" is an ideal model system for investigating the formation and change of fish body color. In this study, to investigate the regulatory role of the pair box 3 (pax3) gene in the early body color fading process of Midas cichlids, the complete cDNA sequence (3513bp) of pax3 was successfully isolated from Midas cichlids (Amphilophus Citrinellus), and found to encode polypeptides of 491 amino acids. Expression patterns of the pax3 gene in tissues of Midas cichlids during different periods, including embryonic development and body color fading stages were detected by quantitative real-time PCR. The qRT-PCR analysis showed that pax3 was expressed in all tissues of adult fish, with a higher expression level in muscle and skin. The highest expression level in muscle tissue was significantly higher than that in other tissues (P<0.05). During embryonic development, the expression tendency of pax3 was first increased and then decreased. In the three typical stages of early skin color fading from black to gold, pax3 expression in skin, caudal fin and scales all showed a downward trend. The expression level in the black stage was significantly higher than that in other stages (P<0.05). Positive signal of pax3 protein was detected in the three typical skin color conversion stages, and the highest positive signal intensity was detected in the black stage, which was consistent with qRT-PCR results. After pax3 RNA interference, pax3 and the downstream genes mitf and tyr all decreased, while dct mRNA expression increased in the skin of fish. Western blotting also showed a decrease in pax3 protein concentration. Those results suggest that pax3 plays an important role in skin color formation, distribution and change in Midas cichlids through the melanogenesis pathway.

The usage of embroideries among the Hezhe in China and the Nanai in Russia. A comparative study of heritagisation processes and their local appropriation

Among the Nanai of Russia, the promotion of the usage of fish skins goes alongside the wider feminine activity of embroidery, known to protect the wearer from evil spirits. In North-East China, the safeguarding of Hezhe crafts, promoted both by UNESCO and the Chinese administration, resulted in the creation of a new type of artefacts made from fish skins. This study shows how cultural policies influence the production of material culture, thereby highlighting the place of each group within a dominating culture (numerically and culturally) and strategies of Indigenous appropriation and agency.

External parasites: how anchor worms affect Iberian endemic fish

Lernaea cyprinacea, commonly known as anchor worm, is a cosmopolitan invasive copepod that parasitizes a wide variety of freshwater fish, including several native and endemic species of the Iberian Peninsula (Sánchez-Hernández 2017), like the Squalius alburnoides from the Guadiana River basin depicted in the photograph, with 3 different individuals attached. Anchor worm was introduced to Iberia from Asia in the 1970s (Simon Vicente et al. 1973). While males are free-living, adult females attach their anchors – a modification of the head – to the fish host, usually in the fins, gills or mouth. Infestation by this external parasite is easily recognised by the wounds, ulcers and inflammatory processes that it induces in the fish skin and muscle (Hossain et al. 2018, see photograph). It may also induce anaemia, malformations, reduced growth and increased susceptibility to secondary infections (Sánchez-Hernández 2017). Small fish are specially affected in their swimming ability, respiration and health condition due to infections and mechanical compression of internal organs, both resulting from the ulcerous skin lesions developed at anchoring sites (Guagliardo &amp; Tanzola 2016). Since infestation prevalence are hypothesised to be positively correlated with higher water temperatures (Marcogliese 2001), outbreaks are expected to increase in intermittent southern Iberian rivers under a global climate change scenario (Macedo-Veiga et al. 2019), which will likely contribute to the aggravation of the conservation status of the already imperilled native fish species. Although broader studies are needed, reported prevalences are higher in native Iberian fish than in sympatric alien species (Macedo-Veiga et al. 2019)

Evaluation of the biocompatibility of fish skin collagen with the mesenchymal stem cells in in vitro cultures.

There are scarce published data suggesting, that collagen extracted from fish skin may be an attractive alternative to mammalian-derived collagen for the in vitro cell cultures. In this study, we investigated proliferation potential and differentiation capability into osteogenic and adipogenic lineages of rat adipose-derived mesenchymal stem cells (rASCs) and human adipose-derived mesenchymal stem cells (hASCs) cultured on collagen extracted from silver carp and African sharptooth catfish skins, compared with commercially available mammalian collagen and collagen-free culture dishes. Our results revealed no significant differences between fish collagen and mammalian collagen in supporting cell viability and proliferation capacity. Fish-derived collagen is a cheap material derived from production waste, does not contain transmissible pathogens of mammalian origin, supports human cell cultures at comparable level to conventional collagen sources, and may be considered as the product of choice for the in vitro cell cultures.

Consensus Recommendations for Optimizing the Use of Intact Fish Skin Graft in the Management of Acute and Chronic Lower Extremity Wounds

Background. Since 2017, the clinical use of IFSG has increased substantially in the United States, with some use in Europe and Asia as well. However, scant consensus data have been published on such use. Objective. The authors sought to develop consensus recommendations for the clinical use of IFSG in the management of acute and chronic LEWs. Methods. A panel of 8 expert clinicians in the United States used a 2-cycle NFG process to develop consensus statements based on their own clinical practice and the literature. At their initial meeting in October 2021, panel members discussed the management of DFUs, VLUs, atypical LEWs, and traumatic LEWs in their practices. Consensus statements were drafted, voted on, and rated by relative importance. At the second meeting in October 2022, the panel discussed the initial survey results; a second survey was conducted, and panel members revised the recommendations and indicated the relative importance of each in the final report. A systematic literature review of English-language articles published from January 2016 through November 2022 was conducted as well, using the search terms: “fish skin,” “piscine graft,” “fish tissue,” “intact fish skin graft,” “Cod skin,” “Omega 3 fatty acid graft.” Results. Forty-three statements were generated and grouped into 5 sections comprising general recommendations for LEWs and recommendations specific to DFUs, VLUs, atypical LEWs, and traumatic LEWs. The primary general recommendation is the need to determine wound etiology based on clinical evaluation and reviewing related test results. For DFUs and VLUs, the main recommendations are to adhere to first-line therapy (ie, standard of care, follow conventional guidelines [multilayer compression therapy], offloading, and assessment of wound perfusion) before introducing IFSG. Conclusions. Publications on and clinical experience in the use of IFSGs have increased substantially in the past several years. The 43 consensus recommendations are meant to guide physicians in the optimal use of IFSG in the management of acute and chronic LEWs.

Brief Synopsis of Insusceptible System and Insusceptible Retorts of Fish

Fish are free-living organic entities from the undeveloped phase of life in their oceanic climate. They have systems to shield themselves from a wide assortment of microorganisms. The point of this course paper is an attempt, to sum up near fish immunology. The immune arrangement of fish is basically the same as vertebrates, despite the fact that there are a few significant contrasts. Lymphoid organs in warm-blooded creatures are additionally found in fish, aside from lymphatic knobs and bone marrow. The season of appearance of lymph myeloid organs in a few types of fish is unique. In fish, the intrinsic reaction is considered a fundamental part of battling microbes. The mucosal surface of the skin, gill and digestive tract are the primary obstruction between the fish and encompassed Environment. Bodily fluid is significant obstruction of fish since it has antimicrobial movement. Fish skin is not the same as that of warm-blooded creatures, since it secretes bodily fluid which is engaged with safe capacities. Lysozyme is exceptionally powerful against gram-positive microorganisms than gram-negative. The fish supplement framework takes into account a more extensive acknowledgment of unfamiliar surfaces when contrasted with that of vertebrates. The advancement of immunological memory is regularly inspected by implication by checking the auxiliary reaction. Memory reaction in fish is feeble in contrast with well-evolved creatures. There are many variables that influence fish immune reaction, the essential one is temperature. Immunomodulatory items, including nucleotides, glucans, and probiotics, are progressively utilized in hydroponics creation. The utilization of these items decreases the requirement for restorative medicines, upgrades the impacts of antibodies, and, thusly, works on the signs of creation.

Fluorescence for non-contact detection of living salmon lice on salmon skin

This work presents a promising method for automatic, non-contact, detection and counting of salmon lice infested on salmon in an aquacultural farm setting. The method uses fluorescence from chitin in the visual part of spectrum to enhance the contrast between fish skin and salmon lice, and show that the fluorescence is even strong enough to give a real-time view of the digestive and reproduction system in live lice without use of staining dyes. The wavelengths used are compatible with an underwater measurement system.

Carotenoid pigment content and skin microscopic appearance of cultured Ajamaru Rainbowfish (Melanotaenia ajamaruensis)

The color of Ajamaru Rainbowfish (Melanotaenia ajamaruensis), which is adapted to the tank culture tends to decrease in brightness and become dull. It is necessary to improve the quality of color, especially through the diet. This study was conducted to determine the effect of the supplementation of carotenoid on the diet on the amount of carotenoid pigments and the microscopic appearance of the skin, fins, and scales of the Ajamaru rainbowfish. The research used a factorial design, consisting of two factors and three replications. The Factors were three different diets (carotenoid-free diet, astaxanthin, and lutein diet) as factor 1, and gender (male and female) as factor 2. The observed data were carotenoid content in fins, skin, and flesh; the microscopic appearance of fins and scales was measured at the end of the study. The results showed that the supplementation of astaxanthin and lutein to the feed increased the content of carotenoid pigments in the fins and scales of the Ajamaru rainbowfish; the highest values in the fins and skin of the male fish were 202.90 and 8.53 ppm, respectively. The effect of astaxanthin and lutein supplementation on color can be observed microscopically in the tissue of scales and fins.