Amphiprion Ocellaris Research Articles

Trophic contamination by octocrylene does not affect aerobic metabolic scope in juveniles clownfish

The effect of trophic exposure to Octocrylene (OC) on aerobic metabolism of clownfish Amphiprion ocellaris was investigated. There were no significant differences in Standard Metabolic Rate (SMR), Active Metabolic Rate (AMR) or aerobic metabolic scope (AS) at the concentration of 10 µg/g of octocrylene in diet of juvenile’s clownfish whatever the time of exposure. This suggests that under these experimental conditions, exposure to OC in food at a concentration of 10 µg/g did not influence aerobic metabolism of this species.

Evaluation of dietary oleoresins on the enhancement of skin coloration and growth in the marine ornamental clown fish, Amphiprion ocellaris (Cuvier, 1830)

A 60-day feeding trial was carried out to investigate the effects of dietary oleoresin inclusion on skin colour intensity, carotenoid content, growth performance and digestive enzyme activities of a high value marine ornamental clown fish, A. ocellaris. Experimental diets were formulated with natural oleoresin pigments namely, paprika, turmeric and chlorophyll, with dietary inclusion at the rate of 20 gkg−1 in the diets. Experimental units were set in triplicates with six numbers of fish in each tank and maintained in filtered sea water of 20‰ salinity in a recirculatory system. Clown fish with average initial weight of 150.6 ± 0.10 mg and initial length of 8 mm were fed five different diets viz., control/ basal diet (C), diets with inclusion at the rate of 20 gkg−1 each of paprika (PAP), turmeric (TUR) and chlorophyll (CHL) oleoresins and combination of oleoresins (COM) at the rate of 20 gkg−1. Skin colour intensity in terms of red and yellow hues and total carotenoid levels differed significantly (P < .05) and highest intensity was recorded in fishes fed the PAP, followed by the COM group. Fish fed with the diet containing COM showed significantly higher final body weight, specific growth rate, weight gain % and feed efficiency as compared to other treatments and was followed by the PAP group. The whole body carotenoid content was highest in COM and PAP groups. There were no significant differences (P > .05) with respect to feed efficiency, digestive enzyme activities, viscero somatic index, visceral length index, condition factor and whole body proximate composition among different treatments. These results suggested that the dietary pigments have a direct influence on the skin pigmentation in A. ocellaris without adverse effects on digestive functions and body condition. Colour imparted in fish skin due to paprika oleoresin was found to be superior.

The complete mitochondrial genome of the Picasso clownfish: genomic comparisons and phylogenetic inference among Amphiprioninae

Picasso clownfish belong to the subfamily Amphiprioninae and are considered a variant of the genus Amphiprion. In this study, we first sequenced the complete mitochondrial genome of the Picasso clownfish by Illumina next-generation sequencing technology. The length of the whole mitogenome is 16,727 bp long, with a gene arrangement and composition similar to those of two other Amphiprion species (Amphiprion ocellaris and Amphiprion percula). The topological structure of the phylogenetic tree shows that the Picasso clownfish is more closelyrelated to A. percula than it is to A. ocellaris, suggesting that the Picasso clownfish may be a variant of A. percula.

Behavioural differences between breeding and nonbreeding pairs of protandry monogamous false clown anemonefish Amphiprion ocellaris

Anemonefishes are some of the most popular marine ornamental fishes. Due to the adverse impacts of commercial fishing on the wild populations of anemonefishes, a more suitable and efficient captive breeding programme must be promoted. In the wild, anemonefishes are protandrous sex-changing fish, but when two immature individuals with ambisexual gonads are raised together in captivity, the two differentiate directly into a male and a female, to form a breeding pair. However, not all the formed pairs spawn, explaining the great care required in captive breeding. This behaviour appears to be counter-adaptative, as anemonefish social groups form randomly in the wild, and such phenomenon would disturb their breeding success. This study evaluated the behavioural and physiological differences between breeding and nonbreeding pairs of false clown anemonefish Amphiprion ocellaris under captive conditions. Behavioural observations revealed that nonbreeding females monopolized the shelter provided, whereas breeding females allowed breeding males to use the shelter and the pair frequently stayed together in the shelter. Both nonbreeding and breeding females possessed mature ovarian tissue and similar level of plasma estradiol concentrations, but nonbreeding males had a smaller amount of testicular tissue and lower plasma 11-ketotestosterone levels compared to breeding males.

MODELING AND STRUCTURAL ANALYSIS OF ACETYLCHOLINESTERASE ENZYME OF FISHES

Objective: Computational studies on fish brain acetylcholinesterase were conducted, expanding our views and for a deeper understanding of the activity of the fish acetylcholinesterase enzyme.&#x0D; Methods: Physico-chemical properties of the fish acetylcholinesterase enzyme were studied. Homology model of the acetylcholinesterase enzyme was predicted, validated its quality and active sites were predicted. The amino acid frequency in the active sites was also compared. Similarly, the secondary structure of the sequences was predicted and compared. Phylogenetic analysis was performed by the neighbour joining tree method.&#x0D; Results: Among the selected fish species stability of acetylcholinesterase was found in fish species namely Esox lucius. The negative GRAVY score value of enzyme in all the fish species ensured better interaction and activity in the aqueous phase. It was found that the molecular weight of the acetylcholinesterase enzyme ranged between 9113 and 15991 Da. Iso-electric (pI) of acetylcholinesterase was found to be acidic in nature. GOR IV was used to predict the secondary structure of acetylcholinesterase, which showed that random coil was dominated. Neighbor joining tree of the enzyme showed that fish species named Amphiprion ocellaris as the most divergent species, while the species Oreochromis niloticus is the most primitive one.&#x0D; Conclusion: Acetlycholinesterase enzyme of Esox lucius was found to be the best compared to the other species, which possess a high number of active sites with Ile, Set and Glu rich active sites.

Characterization of a novel picornavirus isolated from moribund aquacultured clownfish.

Over the last decade, a number of USA aquaculture facilities have experienced periodic mortality events of unknown aetiology in their clownfish (Amphiprion ocellaris). Clinical signs of affected individuals included lethargy, altered body coloration, reduced body condition, tachypnea, and abnormal positioning in the water column. Samples from outbreaks were processed for routine parasitological, bacteriological, and virological diagnostic testing, but no consistent parasitic or bacterial infections were observed. Histopathological evaluation revealed individual cell necrosis and mononuclear cell inflammation in the branchial cavity, pharynx, oesophagus and/or stomach of four examined clownfish, and large basophilic inclusions within the pharyngeal mucosal epithelium of one fish. Homogenates from pooled external and internal tissues from these outbreaks were inoculated onto striped snakehead (SSN-1) cells for virus isolation and cytopathic effects were observed, resulting in monolayer lysis in the initial inoculation and upon repassage. Transmission electron microscopy of infected SSN-1 cells revealed small round particles (mean diameter=20.0-21.7 nm) within the cytoplasm, consistent with the ultrastructure of a picornavirus. Full-genome sequencing of the purified virus revealed a novel picornavirus most closely related to the bluegill picornavirus and other members of the genus Limnipivirus. Additionally, pairwise protein alignments between the clownfish picornavirus (CFPV) and other known members of the genus Limnipivirus yielded results in accordance with the current International Committee on Taxonomy of Viruses criteria for members of the same genus. Thus, CFPV represents a proposed new limnipivirus species. Future experimental challenge studies are needed to determine the role of CFPV in disease.

Synergistic Effects of Ocean Warming and Cyanide Poisoning in an Ornamental Tropical Reef Fish

An array of anthropogenic pressures is affecting tropical ecosystems, posing major conservation challenges for scientists, stakeholders and populations. Illegal cyanide fishing is one of the major threats to Indo-Pacific coral reefs, targeting a multitude of colorful species for the marine aquarium trade as well as large-sized groupers and wrasses for the food fish trade. Ultimately, the continued use of this destructive practice as oceans warm may overload tropical ecosystems and result in irreversible ecological damage. Here we show that the impact of cyanide poisoning in ornamental tropical marine fish is magnified under increased temperatures. A sole pulse exposure of 60 seconds to 50 mg L-1 of cyanide under current temperature (26 oC) caused substantial mortality (50-100 %) in eight species of Pomacentridae. The clownfish Amphiprion ocellaris was the most resilient, especially medium-sized fish (average total length and weight of 38 mm and 1.12 g; LC50 (95% CI) = 50.00 (46.76 – 53.24) mg L-1) that showed shorter recovery times and higher survival rates (%) when compared to small-sized ones (average total length and weight of 25 mm and 0.30 g; LC50 (95% CI) = 28.45 (20.17 – 36.72) mg L-1). However, when the most resistant size-class was concomitantly exposed to a sub-lethal dosage of cyanide (25 mg L-1 instead of 50 mg L-1) and ocean warming scenarios for 2100 (+3 oC and heat wave +6 oC), survival rates (%) decreased to 60 % and 20 %, respectively and recovery times increased in the worst case scenario. Mortality outbreaks, as well as vulnerability to predation, will likely expand in fish inhabiting coral reefs exposed to cyanide fishing unless stronger conservation measures are taken in tropical reefs to limit this destructive practice now and in the oceans of tomorrow.

Autochthonous bacterium Lactobacillus plantarum as probiotic supplementation for productive performance and sanitary improvements on clownfish Amphiprion ocellaris

This current study evaluated the probiotic dietary supplementation with autochthonous bacterium Lactobacillus plantarum for Amphiprion ocellaris. Therefore, it was performed an experiment in complete randomized design with four treatments (T1: Control without probiotic; T2: 104; T3: 106 and T4: 108 CFU/g of ration) and three replicates. Juvenile fish (n = 120; 0.46 ± 0.01 g and 0.26 ± 0.06 cm) were distributed in twelve aquarium (80 L) and it received trial meal three times a day at fed rate of 4% live weight during 90 days. The fish were monthly measured and determined the total length, standard length, height, weight gain, biomass gain, specific growth rate, apparently feed conversion, relative condition factor, uniformity and survival. At the end of experiment (90 days) fish were submitted to hematological (n = 9/ treatment; Erythrogram, Leukogram and Thrombogram) and histological analysis (n = 6/ treatment; Intestinal tract). Also, after the supplementation period, the fish were challenged with pathogenic bacteria and the survival and blood analyzed. Results showed the fish fed T3 and T4 had improvement on weight gain, feed conversion, specific growth rate, height and total height from the intestinal villi. Increases of red blood cell (Erythrocyte, hematocrit and hemoglobin) and white blood cell (Lymphocyte and monocyte) also observed to both treatments (T3 and T4), However the T4 promoted the greater fish resistance to pathogenic bacteria. As conclusion, probiotic supplementation with the autochthonous bacterium Lactobacillus plantarum 106 CFU/g provides zootechnical improvement for clownfish rearing, but to improve the pathogenic infection resistance, the 108 CFU/g presented more adequate.

Steroidal regulation of the aromatase gene and dominant behavior in the false clown anemonefish Amphiprion ocellaris

The interaction between cortisol and aromatase may be a critical factor in sex determination or sex changes in teleost species. High cortisol concentrations inhibit transcription of the aromatase gene, resulting in masculinization. Anemonefish (Amphiprion spp.) are socially controlled, protandrous sex-changing fish, with a monogamous mating system. Females are the largest and most dominant members of social groups, second-ranking individuals become males, and other individuals remain nonreproductive. Individuals that change from male to female display high plasma cortisol concentrations, contrary to a previously established mechanism of masculinization. We investigated the effects of exogenous steroids on gene expression in the brain and gonads and on the occurrence of dominant behavior in the sexually immature ambisexual false clown anemonefish Amphiprion ocellaris. Transcription of the cyp19a1a aromatase gene increased in the gonads of estradiol pellet-fed fish but decreased in cortisol pellet-fed fish. Dominant behavior intensity significantly increased in estradiol pellet-fed fish, but decreased in cortisol pellet-fed fish. Methyltestosterone had no apparent effect on gene transcription or behavior. These results suggest that the masculinization mechanism induced by cortisol is common among teleost species, including protandrous sex-changing fish, and that behavioral changes induced by steroid supplements reflect social status in A. ocellaris.

Spontaneous alloparental care of unrelated offspring by non-breeding Amphiprion ocellaris in absence of the biological parents

Many species display alloparental care, where individuals care for offspring that are not their own, but usually the behavior is contingent on the individual receiving some direct or indirect benefit. In anemonefish, after removing the breeding male, non-breeders have been observed providing care for eggs they did not sire and which are not kin. Previously this behavior was interpreted as coerced by the female. The purpose of this study was to test the alternative hypothesis that the alloparental care occurs spontaneously without prodding by the female. Groups of Amphiprion ocellaris (male, female and non-breeder) were maintained in the laboratory and behavior monitored after removing the male and both the male and female. Non-breeders began to care for eggs after male removal and further increased parental care after male and female removal. Level of care was not as high as experienced males, but additional experiments showed performance increases with experience. In a separate experiment, non-breeders were placed alone in a novel aquarium and eggs from an established spawning pair were introduced. Approximately 30% of the fish displayed extensive fathering behavior within 90 min. Taken together, our results demonstrate that fathering behavior in A. ocellaris occurs spontaneously, independent of paternity or kinship.

Nonapeptides mediate trade-offs in parental care strategy

Parental care represents a suite of distinct behaviors performed by parents to maximize fitness. Dynamic shifts in parental care behaviors, such as between nest defense and direct provisioning of the offspring, are required in response to environmental variation. However, the neural mechanisms which mediate such behavioral shifts remain a mystery. The anemonefish, Amphiprion ocellaris, represents an experimentally valuable model in social neuroscience which is conducive to manipulating the environment while simultaneously measuring parental care. The goal of this study was to determine the extent to which arginine vasotocin (AVT) and isotocin (IT) signaling are necessary for males to shift between direct egg care and aggressive nest defense in the presence of intruders, Domino damselfish (Dascyllus trimaculatus). The IT receptor antagonist desGly-NH2-d(CH2)5[D-Tyr2,Thr4]OVT, significantly reduced direct egg care, while at the same time increased levels of aggressive nest defense relative to vehicle. Conversely, blockade of AVT using the antagonist d(CH2)5[Tyr(Me)2]AVP, reduced aggression and tended to increase egg care. Results demonstrate that male anemonefish alter their parental strategy in response to allospecific intruders, and that IT and AVT signaling oppositely regulate parental care displays of aggression versus egg care.

The effect of spatial position and age within an egg-clutch on embryonic development and key metabolic enzymes in two clownfish species, Amphiprion ocellaris and Amphiprion frenatus.

Since the size of newly hatched larval fish is directly related to egg size, small differences in initial egg size can be critical to survival and further development of offspring. Underlying processes causing size variation in fish offspring are still not entirely understood. In this study we investigated whether the spatial position of an individual egg within a clutch affects size variation in two benthic spawning coral reef fishes, the clownfishes Amphiprion ocellaris and A. frenatus. To evaluate the effects of within-clutch position on embryonic development, egg growth metrics and protein content were analysed on day 2, 5 and 8 after deposition (adp). Additionally the activities of the key metabolic enzymes citrate synthase (CS) and lactate dehydrogenase (LDH) were investigated to evaluate the physiological status of the embryos. Central eggs of A. frenatus were significantly longer and heavier than peripheral eggs only on day 2 and 5 adp (2.07 mg, 2.59 mm vs. 1.84 mg, 2.49 mm). No significant differences were observed in A. ocellaris between eggs originating from a central or peripheral (5 mm from edge) position (1.33 mg, 2.26 mm vs. 1.15 mg, 2,18 mm). Diameter of the eyes did not differ between the two fish species nor between different positions, for any age group. The protein content of eggs (7.5% of wet weight) was independent of age, position and species. Enzymatic activity increased from 2 adp until peak activity was observed for both enzymes on day 8 adp, independent from position. The range of CS- and LDH-activity was 0.3–13.0 and 0.2–71.7 U g-1 wet weight, respectively. Significant differences in enzymatic activity were observed between age groups in both species, which in connection with significantly larger eggs of A. frenatus at day 2 and 5 adp could hint at a better O2 supply of central eggs. Potential implications for captive breeding are given.

Microplastic ingestion rates are phenotype-dependent in juvenile anemonefish

The potential influence of microplastic debris on marine organisms is an issue of great ecological and socioeconomic concern. Experiments exposing fishes and invertebrates to constant concentrations of microplastics often yield high variation in particle ingestion rates among individuals. Yet, despite an increasing interest in microplastic ingestion in the wild, the potential intrinsic drivers of inter-individual variation have received little attention so far. Here we assessed individual-level ingestion of Polyethylene microspheres by laboratory-reared juvenile anemonefish, Amphiprion ocellaris, in relation to (a) ambient particle concentrations and (b) repeatable behavioural traits. We show that microplastic ingestion is highly variable at all tested particle concentrations and that this variation can partially be explained by individual activity levels. Moreover, the relationship between ingestion and behavioural variation increased notably when only the most behaviourally consistent individuals (n = 40 out of 60) were considered in the analysis. Our findings indicate that microplastic ingestion rates in juvenile reef fishes may be less dependent on ambient concentrations than expected; instead they are to some degree phenotype-dependent. Care should thus be taken when reporting mean responses to microplastic exposure treatments, because some individuals may not be affected in the same way as others due to differential ingestion behaviour. We also discuss potential ramifications of non-random ingestion variability on population- and community-level responses.

Reproductive characteristics of coral-reef fishes, Pomacentridae, Monodactylidae and Chaetodontidae, in the east coast of Peninsula Malaysia

In order to understand the reproductive ecology of coral-reef fishes, fecundity which is the physiological maximum potential reproductive output, was examined in eleven families of coral-reef fishes in the east coast of Peninsula Malaysia. Three families, Pomacentridae, Monodactylidae and Chaetodontidae, with five species, Amphiprion ocellaris, Amphiprion perideraion, Abudefduf bengalensis, Monodactylus argenteus and Chaetodon octofasciatus, could collect female specimens, while all specimens were male in eight out of eleven families with sixteen species. Mean fecundities ranged from 693 to 122,247 with the lowest fecundity was found in Pomacentridae, and Chaetodontidae had the highest fecundity. Amphiprion ocellaris and A. perideraion practice parental care with demersal spawners, and such unique reproductive ecology might produce lower number of eggs to be able to increase their reproductive success compared to other coral reef fishes spawned pelagic eggs. This study provides an insight of baseline knowledge of the reproductive biology of coral-reef fishes for future studies of important fish species in coral ecosystem.

Sea anemone and clownfish microbiota diversity and variation during the initial steps of symbiosis

Clownfishes and sea anemones form an intriguing long-term association, but the mechanism underlying this symbiosis is not well understood. Since clownfishes seem to cover themselves with sea anemone mucus, we investigated the microbiomes of the two partners to search for possible shifts in their compositions. We used a 16S rRNA gene sequencing strategy to study the dynamics of the microbiota during the association between the clownfish Amphiprion ocellaris and its host Heteractis magnifica under laboratory conditions. The experiment conducted in aquaria revealed that both clownfish and sea anemone mucus had specific signatures compared to artificial sea water. The microbiomes of both species were highly dynamic during the initiation of the symbiosis and for up to seven days after contact. Three families of bacteria (Haliangiaceae, Pseudoalteromonadacae, Saprospiracae) were shared between the two organisms after symbiosis. Once the symbiosis had been formed, the clownfishes and sea anemone then shared some communities of their mucus microbiota. This study paves the way for further investigations to determine if similar microbial signatures exist in natural environments, whether such microbial sharing can be beneficial for both organisms, and whether the microbiota is implicated in the mechanisms that protect the clownfish from sea anemone stinging.

Glycolytic capacities depend on developmental stage in the clownfish Amphiprion ocellaris

Glycolytic capacities depend on developmental stage in the clownfish Amphiprion ocellaris

In vitro selection of autochthonous lactic acid bacterium from clownfish Amphiprion ocellaris

In vitro selection of autochthonous lactic acid bacterium from clownfish <i>Amphiprion ocellaris</i>

Some methods to stain cartilage and bone of vertebrates and application on small fish in museum of oceanography

In a natural scientific museum as Museum of Oceanography, a specimen should be not only awesome but also scientific in order to attract visitors and introduce knowledge to them. One of the methods satisfying those requirements is “Method of staining cartilages and bones for small vertebrates”. This method was applied to handle small fish: Anchovies (Encrasicholina devisi (Whitley, 1940)), amphiprions (Amphiprion ocellaris (Cuvier 1830)) and ponyfish (Leiognathus sp.), which is highly efficient, not only used in studying fish bones and cartilages but also attractive to visitors. This paper also gives details on experiences during handling process of this method.

Effect of enriching live feeds with HUFA on growth and survival of clownfish &lt;i&gt;Amphiprion ocellaris&lt;/i&gt; (Cuvier, 1830) larvae

The aims of this study was to evaluate the effect of HUFA-enriched live feed in rearing Nemo fish larvae (Amphiprion ocellaris), 5 treatments were set up (each treatment was repeated in triplicate) with 5 concentrations of HUFA (Super Selco) (0, 50, 100, 150 and 200 ppm). After 45 days of culture with HUFA-enriched live feeds of different concentrations, the total length-TL as well as the specific growth rate (SGRL) in body length and survival rate of Nemo fish larvae in the treatments had significant differences (p &lt; 0.05). In the enriched live prey diet of 100 ppm Selco, TL, SGRL and the survival rate of Nemo fish larvae were the highest (10.01 ± 0.150 mm, 7.20 ± 0.099%/day and 82.67 ± 0.881%, respectively). Lowest TL, SGRL and survival rate were obtained in larvae fed with the control diet (8.65 ± 0.051 mm, 6.23 ± 0.041%/day and 68.70 ± 0.881%, respectively). The results of this experiment suggest that the optimal Selco concentration used to enrich live feeds for Nemo fish larvae is 100 ppm, which can improve the production efficiency of Nemo stock.

Thermal preference, tolerance, and thermal aerobic scope in clownfish Amphiprion ocellaris (Cuvier, 1830) predict its aquaculture potential across tropical regions

The clownfish Amphiprion ocellaris is widely distributed in the coral reef ecosystems of tropical and subtropical regions of the West Indo Pacific, an area that hosts economically valuable species, and, thus, a suitable candidate for warm water aquaculture. This study determined the preferred temperature, critical threshold limits, represented by critical thermal maximum and critical thermal minimum, thermal window width, and aerobic metabolic scope of A. ocellaris clownfish acclimated to 20, 23, 26, 29, 32, and 35 °C. A positive response (P < 0.05) occurred when the preferred temperature significantly increased with increasing acclimation temperature. The preferred temperature obtained graphically was 30.0 °C. Acclimation temperature significantly affected the thermal tolerance which increased with acclimation temperature. The thermal window calculated for A. ocellaris was 301.5 °C2. The thermal metabolic scope obtained in animals acclimated at the interval from 23 to 32 °C (P > 0.05) had a mean value of 4240.8 mg O2 h−1 kg−1 w.w., revealing that A. ocellaris is a eurythermal species with a range of optimal physiological performance that closely matches the environmental conditions where it can be farmed. Therefore, the highest value of the thermal aerobic scopes corresponded to the intervals of the preferred temperature obtained for A. ocellaris. These results may partially explain their worldwide distribution pattern, as well as their aquaculture potential in tropical regions.