Essential oils from Cymbopogon citratus and Lippia sidoides in the anesthetic induction and transport of ornamental fish Pterophyllum scalare.

This study verified the effects of essential oils from Lippia sidoides (EOLS) and Cymbopogon citratus (EOCC) on the anesthesia of freshwater angelfish (Pterophyllum scalare) of two different sizes (juveniles I (0.82 g) and II (2.40 g)) and the transport (8 h) of juveniles II. Fish were exposed to different concentrations of EOLS and EOCC: 0, 10, 25, 50, 75, 100, 150, 200, and 250 mg L-1. Ventilatory rate (VR) and transport for 8 h with 0, 10, and 15 mg L-1 of each essential oil were evaluated in juveniles II. The major components found in EOLS and EOCC were carvacrol (44.50%) and α-citral (73.56%), respectively. The best sedation and anesthesia times for both essential oils were obtained with 10 and 25 mg L-1 and 200 and 250 mg L-1 for juveniles I and II, respectively. Fish sedated with EOLS had lower VR values than the other treatments. Blood glucose levels were higher in ornamental fish transported with 10 and 15 mg EOLS L-1 and 15 mg EOCC L-1. Hepatic glycogen values were higher in the control group. In general, fish transported with 10 mg EOLS L-1 showed fewer gill histological alterations than other transported fish. When the type of lesion was evaluated, the highest gill alterations occurred in fish transported with EOCC. In conclusion, 10 mg EOLS L-1 could be used to transport of juveniles II because although this concentration increased blood glucose levels, it decreased the VR and muscle glycogen levels and caused only mild alterations to the gills.

Video playback versus live stimuli to assess quantity discrimination in angelfish (Pterophyllum scalare).

Video playback is a widely used technique for presentation of visual stimuli in animal behavior research. In the analysis of behavioral responses to social cues, presentation of video recordings of live conspecifics represents a consistently reproducible stimulus. However, video-recordings do not interact with the experimental subject, and thus this stimulus may be inferior in the social context. Here, we evaluated how angelfish (Pterophyllum scalare) respond to a video playback of conspecifics versus a live shoal of conspecifics. Using binary choice tests, subjects were presented different stimuli. Time spent close to one versus the other stimulus was considered an index of preference. We found angelfish to prefer a live shoal of conspecifics to an empty tank, and also the video playback of a shoal of conspecifics to a blank screen, although the level of preference in the latter was lower than in the former. These results indicate that video-playback of live conspecifics may be appropriate in angelfish, thus allowing manipulation of specific cues that angelfish may use in quantity discrimination. However, when we directly contrasted a live and a video recorded shoal, both having the same number of members, experimental fish preferred the live shoal. When the choice consisted of a live shoal of four conspecifics versus a video playback of a shoal of nine conspecifics no clear preference emerged. These results imply that video-playback has disadvantages in quantity discrimination studies with angelfish. Exploring procedural and/or technological parameters will verify the suitability of video-recording-based stimulus presentation for future use in angelfish.

Reproductive Cycle of Blue-Striped Angelfish, Chaetodontoplus septentrionalis in Jeju Coastal Waters.

Reproductive cycle of the blue-striped angelfish, Chaetodontoplus septentrionalis were histologically investigated. Fish were monthly collected in the coastal waters of Munseom, Seogwipo, Jeju-Island from February to December 2018. The gonadosomatic index (GSI) increased from May and maintained high values in August. The reproductive cycle of female fish can be classified by the characteristics observed during gonadal development as followed: growing stage (November to June), early mature stage (May to June), mature and spawning stage (June to September), and degenerative and recovery stage (September to December). In the male, testicular development period was similar to that of ovarian development period, but mature and spawning period was one month longer from June to October. Fecundity of mature female ranged from 4,601 to 22,840 and was correlated positively with total length and body weight. The histological analysis of gonadal development indicated that the C. septentrionalis was summer-spawning type and is considered a multiple spawner during spawning season.

Understanding behaviour to improve the welfare of an ornamental fish.

Some common practices in aquaculture, ornamental trade and fish facilities may disturb the behavioural repertoire of fish and its natural adaptive value, reducing welfare and impairing fish production. Hence, it is necessary to understand fish behaviour, as well as the factors affecting it, to improve the quality of fish's life under artificial environment. Here, we reviewed the behaviour of the angelfish Pterophyllum scalare, an Amazonian cichlid used worldwide both as an ornamental fish and as a fish model in scientific research. We characterized social, reproductive and feeding behaviour, as well as the amazing cognitive ability of the angelfish. In addition, we reviewed the effects of environmental enrichment and suggested some important variables that need to be considered for rearing P. scalare. In this review, we show for the first time a synthesis on behaviour and a best practice overview to improve the welfare of angelfish as a target species. Nonetheless, most topics reviewed fit a broader set of fish species, particularly ornamental ones. This synthesis can therefore open a path for further behavioural research applied to the welfare of angelfish and bring insights to other fish species.

Food Quantity Discrimination in Angelfish (Pterophyllum scalare): The Role of Number, Density, Size and Area Occupied by the Food Items.

Quantity discrimination, the ability to identify, process, and respond to differences in number, has been shown in a variety of animal species and may have fitness value. In fish, the ability to distinguish between numerically different shoals has been well studied. However, little work has been devoted to the investigation of such ability in a foraging context. Nevertheless, angelfish (Pterophyllum scalare) have been previously shown to be able to discriminate numerically different sets of food items, with variables such as size and density of the food items playing important roles in making the choice. Here, we examine the possible role of other numerical and non-numerical variables. Using a spontaneous binary choice task, we contrasted sets of food items differing in specifically controlled ways: (1) different numerical size but equal inter-item distance; (2) different numerical size and different inter-item distance; and (3) identical total contour length and area occupied but different individual food size and inter-food distance between the contrasted food sets. In Experiment 1, angelfish were found to prefer the sets with a large number of food items. In Experiment 2, they preferred the numerically smaller sets with clustered items to the numerically larger sets with scattered items, but only when the sets were in the large number range (10 vs. 5 food items). Finally, in Experiment 3 fish preferred numerically smaller sets with large-sized and scattered food items in the large number range sets. We conclude that food item number, density, and size may not be considered individually by angelfish, but instead, the fish respond to all these factors attempting to maximize energy gained from eating the food while minimizing energy expenditure collecting and/or protecting the food.

Quantity discrimination in angelfish (Pterophyllum scalare) is maintained after a 30-s retention interval in the large but not in the small number range.

The ability to discriminate between sets that differ in the number of elements can be useful in different contexts and may have survival and fitness consequences. As such, numerical/quantity discrimination has been demonstrated in a diversity of animal species. In the laboratory, this ability has been analyzed, for example, using binary choice tests. Furthermore, when the different number of items first presented to the subjects are subsequently obscured, i.e., are not visible at the moment of making a choice, the task requires memory for the size of the sets. In previous work, angelfish (Pterophyllum scalare) have been found to be able to discriminate shoals differing in the number of shoal members both in the small (less than 4) and the large (4 or more) number range, and they were able to perform well even when a short memory retention interval (2-15 s) was imposed. In the current study, we increased the retention interval to 30 s during which the shoals to choose between were obscured, and investigated whether angelfish could show preference for the larger shoal they saw before this interval. Subjects were faced with a discrimination between numerically small shoals (≤4 fish) and also between numerically large (≥4 fish) shoals of conspecifics. We found angelfish not to be able to remember the location of larger versus smaller shoals in the small number range, but to exhibit significant memory for the larger shoal in the large number range as long as the ratio between these shoals was at least 2:1. These results, together with prior findings, suggest the existence of two separate quantity estimation systems, the object file system for small number of items that does not work with the longer retention interval and the analogue magnitude system for larger number of items that does.

Angelfishes, Paper Tigers, and the Devilish Taxonomy of the Centropyge flavissima Complex.

The pygmy angelfishes (genus Centropyge) provide numerous examples of discordance between color morphology, taxonomy, and evolutionary genetic lineages. This discordance is especially evident in the Centropyge flavissima complex, which includes three primary color morphs, three previously recognized species (C. flavissima, Centropyge eibli, and Centropyge vrolikii) and three distinct mitochondrial (mtDNA) lineages that do not align with species designations. Our previous research showed that the putative C. flavissima arose independently in the Indian and Pacific Oceans, and the three mtDNA lineages align with geography rather than species assignments. Here, we add 157 specimens to the previous dataset of 291 specimens, spread across a greater geographic range, to pinpoint the distribution of mtDNA lineages and color morphs. We found that the mtDNA lineages show remarkably strong geographic boundaries corresponding to the Indian Ocean, Central-West Pacific, and Central-South Pacific. We also test the validity of the "Black Tiger Centropyge" in the C. flavissima species complex, a taxonomic oddity that is restricted to shoals and atolls off the coast of northwestern Australia, and the newly named Centropyge cocosensis assigned to the C. flavissima lineage in the Indian Ocean. We conclude that the Black Tiger Centropyge is not a valid species but rather an intermediate between sympatric color morphs that correspond to the putative species C. eibli and C. vrolikii Our greater sampling efforts also do not support the genetic distinctiveness of C. cocosensis given shared mtDNA haplotypes with the sympatric C. eibli and C. vrolikii, but instead we find conflicting lines of evidence concerning the taxonomy of this group. We urge caution and taxonomic restraint until the true nature of this species complex can be revealed.

The effects of feeding with synbiotic (Pediococcus acidilactici and fructooligosaccharide) enriched adult Artemia on skin mucus immune responses, stress resistance, intestinal microbiota and performance of angelfish (Pterophyllum scalare).

The aim of this study was to evaluate the effects of feeding on synbiotic (Pediococcus acidilactici and fructooligosaccharide) enriched adult Artemia franciscana on skin mucus immune responses, stress resistance, intestinal microbiota and growth performance of angelfish (Pterophyllum scalare). Three hundred and sixty fish with initial weight 3.2 ± 0.13 g were randomly divided into twelve aquaria (50 L) assigned to four groups in triplicates. Fish were fed for 7 weeks with dietary treatments, including treatment 1: feeding adult Artemia without enrichment (control group), treatment 2: feeding adult Artemia enriched with lyophilised probiotic P. acidilactici (700 mg L(-1)), 3: feeding adult Artemia enriched with prebiotic fructooligosaccharide (FOS) (100 mg L(-1)), group 4: feeding adult Artemia enriched with synbiotic (P. acidilactici (700 mg L(-1)) + FOS (100 mg L(-1))). Skin mucus immune responses (lysozyme activity, total Immunoglobulin and protease), stress resistance against environmental stress (acute decrease of temperature and increase salinity), intestinal microbiota as well as growth indices were measured at the end of feeding trial. Artemia enriched with synbiotic significantly improved growth performance compared to other treatments (P < 0.05). The highest weight gain and specific growth rate (SGR) was observed in synbiotic fed fish (P < 0.05). Compared to the other treatments, the population of lactic acid bacteria was significantly higher in the intestinal microbiota of fish fed synbiotic supplemented diet (P < 0.05). In the environmental stress challenge test, the maximum resistance to abrupt decrease of temperature (17 °C) or elevation of salinity (12 g per liter) was observed in the synbiotic treatment. Also, the total immunoglobulin and lysozyme activity level of skin mucus was significantly elevated in fish fed Artemia enriched with synbiotic (P < 0.05). These results revealed that feeding angelfish with synbiotic enriched Artemia was more effective than singular enrichment with probiotics or prebiotics.

The redox-active drug metronidazole and thiol-depleting garlic compounds act synergistically in the protist parasite Spironucleus vortens.

Spironucleus vortens is a protozoan parasite associated with significant mortalities in the freshwater angelfish, Pterophyllum scalare. Control of this parasite is especially problematic due to restrictions on the use of the drug of choice, metronidazole (MTZ), on fish farms. Use of garlic (Allium sativum) is undergoing a renaissance following experimental validations of its antimicrobial efficiency. Ajoene ((E,Z)-4,5,9-trithiadodeca-1,6,11-triene 9-oxide), is a stable transformation product of allicin, the primary biologically active component of garlic. In the current study, an ajoene oil crude extract had a minimum inhibitory concentration (MIC) of 40µg/ml against S. vortens. GC-MS and NMR spectroscopy revealed this ajoene extract contained a mixture of the (E) and (Z)-ajoene isomers along with diallyl disulphide (DADS) and diallyl trisulphide (DATS). The only component of the ajoene crude oil found to substantially inhibit S. vortens growth by optical density monitoring (Bioscreen C Reader) was (Z)-ajoene (MIC 16µg/ml). Ajoene oil acted in synergy with MTZ in vitro, reducing the individual MIC of this drug (4µg/ml) by 16-fold, and that of ajoene oil by 200-fold with a fractional inhibitory concentration (FIC) index of 0.263. This synergistic interaction was confirmed in vivo. S. vortens-infected Pterophyllum scalare angelfish dosed orally with 0.5% (v/w) MTZ combined with 0.05% (v/w) ajoene displayed a significant reduction in faecal trophozoite count, whilst those fed on 0.5% MTZ flakes (half the recommended oral dose) alone did not. This study demonstrates for the first time the synergistic interaction between the synthetic drug MTZ and natural ajoene oil both in vitro and in vivo. Future work should evaluate the potential synergy of ajoene and MTZ against MTZ-resistant bacteria and protists.

The complete mitochondrial genome of the Blue-face angelfish, Pomacanthus xanthometapon (Perciformes: Pomacanthidae).

In this study, the complete mitogenome sequence of the Blue-face angelfish, Pomacanthus xanthometapon (Perciformes: Pomacanthidae) has been sequenced by the next-generation sequencing method. The assembled mitogenome consisting of 16,533 bp includes 13 protein coding genes, 22 transfer RNAs, and two ribosomal RNAs genes. The overall base composition of Blue-face angelfish is 28.7% for A, 28.9% for C, 15.9% for G, 26.6% for T and show 84% identities to flame angelfish Centropyge loriculus. The complete mitogenome of the Blue-face angelfish provides essential and important DNA molecular data for further phylogeography and evolutionary analysis for marine angelfish phylogeny.

The complete mitochondrial genome of the Emperor angelfish, Pomacanthus imperator (Perciformes: Pomacanthidae).

In this study, the complete mitogenome sequence of the Emperor angelfish, Pomacanthus imperator (Perciformes: Pomacanthidae) has been sequenced by the next-generation sequencing method. The assembled mitogenome consisting of 16,538 bp, including 13 protein coding genes, 22 transfer RNAs, and two ribosomal RNAs genes. The overall base composition of Emperor angelfish is 28.4% for A, 28.2% for C, 16.2% for G, 27.2% for T and show 82% identities to Bluestripe angelfish Chaetodontoplus septentrionalis. The complete mitogenome of the Emperor angelfish provides essential and important DNA molecular data for further phylogeography and evolutionary analysis for marine angelfish phylogeny.

Next generation sequencing yields the complete mitochondrial genome of the Clarion angelfish, Holacanthus clarionensis (Perciformes: Pomacanthidae).

In this study, the complete mitogenome sequence of the Clarion angelfish, Holacanthus clarionensis (Perciformes: Pomacanthidae) has been sequenced by next-generation sequencing method. The length of the assembled mitogenome is 16,615 bp, including 13 protein coding genes, 22 transfer RNAs, and two ribosomal RNAs genes. The overall base composition of Clarion angelfish is 28.3% for A, 29.3% for C, 16.5% for G, 25.9% for T and show 85% identities to flame angelfish Centropyge loriculus. The complete mitogenome of the Clarion angelfish provides essential and important DNA molecular data for further phylogeography and evolutionary analysis for marine angelfish phylogeny.

Next generation sequencing yields the complete mitochondrial genome of the Japanese angelfish, Centropyge interrupta (Perciformes: Pomacanthidae).

In this study, the complete mitogenome sequence of the Japanese angelfish, Centropyge interrupta (Perciformes: Pomacanthidae), has been sequenced by the next-generation sequencing method. The assembled mitogenome consisting of 16,595 bp includes 13 protein coding genes, 22 transfer RNAs, and two ribosomal RNAs genes. The overall base composition of Japanese angelfish is 27.5% for A, 29.3% for C, 17.3% for G, 25.9% for T, and shows 85% identities to flame angelfish Centropyge loriculus. The complete mitogenome of the Japanese angelfish provides essential and important DNA molecular data for further phylogeography and evolutionary analysis for marine angelfish phylogeny.

The complete mitochondrial genome of the Tiger angelfish, Apolemichthys kingi (Perciformes: Pomacanthidae).

In this study, the complete mitogenome sequence of the Tiger angelfish, Apolemichthys kingi (Perciformes: Pomacanthidae), has been sequenced by the next-generation sequencing method. The assembled mitogenome consisting of 16,816 bp includes 13 protein coding genes, 22 transfer RNAs, and two ribosomal RNAs genes. The overall base composition of Tiger angelfish is 28.1% for A, 29.4% for C, 16.7% for G, 25.7% for T and show 86% identities to flame angelfish Centropyge loriculus. The complete mitogenome of the Tiger angelfish provides essential and important DNA molecular data for further phylogeography and evolutionary analysis for marine angelfish phylogeny.

The complete mitochondrial genome of the Vermiculated angelfish (Chaetodontoplus mesoleucus) (Perciformes: Pomacanthidae).

In this study, the complete mitogenome sequence of the Vermiculated angelfish (Chaetodontoplus mesoleucus) (Perciformes: Pomacanthidae) has been sequenced by the next-generation sequencing method. The assembled mitogenome consisting of 16,998 bp, including 13 protein coding genes, 22 transfer RNAs, and two ribosomal RNAs genes. The overall base composition of vermiculated angelfish is 27.6% for A, 30.7% for C, 16.1% for G, and 25.6% for T and show 85% identities to Bluestripe angelfish C. septentrionalis in the same genus. The complete mitogenome of the Vermiculated angelfish provides essential and important DNA molecular data for further phylogeography and evolutionary analysis for marine angelfishes.

Next generation sequencing yields the complete mitochondrial genome of the Regal angelfish, Pygoplites diacanthus (Perciformes: Pomacanthidae).

In this study, the complete mitogenome sequence of the Regal angelfish, Pygoplites diacanthus (Perciformes: Pomacanthidae) has been sequenced by the next-generation sequencing method. The assembled mitogenome consisting of 16,784 bp includes 13 protein coding genes, 22 transfer RNAs, and two ribosomal RNAs genes. The overall base composition of Regal angelfish is 28.5% for A, 28.9% for C, 16.3% for G, 26.4% for T and show 85% identities to flame angelfish Centropyge loricula. The complete mitogenome of the Regal angelfish provides essential and important DNA molecular data for further phylogeography and evolutionary analysis for marine angelfish phylogeny.

The complete mitochondrial genome of the Spectacled angelfish, Chaetodontoplus conspicillatus (Perciformes: Pomacanthidae).

In this study, the complete mitogenome sequence of the Spectacled angelfish, Chaetodontoplus conspicillatus (Perciformes: Pomacanthidae) has been sequenced by next-generation sequencing method. The assembled mitogenome consisting of 16,988 bp, includes 13 protein-coding genes, 22 transfer RNAs and 2 ribosomal RNAs genes. The overall base composition of C. conspicillatus is 27.8% for A, 29.9% for C, 16.3% for G and 26.0% for T and show 92% identities to Bluestripe angelfish C. septentrionalis. The complete mitogenome of the C. conspicillatus, provides essential and important DNA molecular data for further phylogeography and evolutionary analysis for marine angelfish phylogeny.

Complete mitogenomes of Guinean angelfish (Holacanthus africanus) and Rock beauty (Holacanthus tricolor) (Teleostei: Pomacanthidae).

In this study, we used the next-generation sequencing method to deduce two complete mitogenomes of Guinean angelfish (Holacanthus africanus) and Rock beauty (Holacanthus tricolor) for the first time. The assembled mitogenome, consisting of 16,819 bp and 16,625 bp in length, shows 87% similarity with each other. Both mitogenomes follow the typical vertebrate arrangement, including 13 protein-coding genes, 22 transfer RNAs, 2 ribosomal RNAs genes, and a non-coding control region of D-loop. The D-loop contains 1107 bp in H. africanus and 905 bp in H. tricolor and is located between tRNA-Pro and tRNA-Phe. The overall GC content is 46.2% for H. africanus and 45.6% for H. tricolor. The complete mitogenome of Guinean angelfish and Rock beauty deduced in this study provides essential and important DNA molecular data for further phylogenetic and evolutionary analysis for marine angelfish.

Complete mitogenomes of Woodhead's angelfish (Centropyge woodheadi) and Herald's angelfish (Centropyge heraldi) (Teleostei: Pomacanthidae).

In this study, we used the next-generation sequencing method to deduce two complete mitogenomes of Woodhead's angelfish (Centropyge woodheadi) and Herald's angelfish (Centropyge heraldi) for the first time. The assembled mitogenome, consisting of 16 863 and 16 836 bp, shows 95.3% identity to each other. Both mitogenome follow a typical vertebrate arrangement, including 13 protein-coding genes, 22 transfer RNAs, 2 ribosomal RNAs genes and a non-coding control region of D-loop. D-loop contains 1158 bp in C. woodheadi and 1129 bp in C. heraldi and locates between tRNA-Pro and tRNA-Phe. The overall GC content is 47.9% for C. woodheadi and 47.5% for C. heraldi. The complete mitogenomes of C. woodheadi and C. heraldi provide an essential and important DNA molecular data for phylogenetic and evolutionary analysis for marine angelfish.

Complete mitogenomes of Armitage angelfish (Apolemichthys armitagei) and Griffisi angelfish (Apolemichthys griffisi) (Teleostei: Pomacanthidae).

In this study, we used the next-generation sequencing method to deduce complete mitogenomes of Armitage angelfish (Apolemichthys armitagei) and Griffisi angelfish (A. griffisi) for the first time. The assembled mitogenomes, consists 16,551 bp (A. armitagei) and 16,528 bp (A. griffisi) in length, shows 92% identity each other. Both mitogenomes follow the typical vertebrate arrangement, including 13 protein coding genes, 22 transfer RNAs, two ribosomal RNAs genes, and a non-coding control region of D-loop. D-loop contains a length of 828 bp in A. armitagei and 849 bp in A. griffisi and locates between tRNA-Pro and tRNA-Phe. Complete mitogenomes of Armitage angelfish and Griffisi angelfish deduced in this study provide essential and important DNA molecular data for further phylogenetic and evolutionary analysis for marine angelfish.