Search

Habitat heterogeneity shapes biological communities, a well-known process in terrestrial ecosystems but substantially unresolved within coral reef ecosystems. We investigated the extent to which coral richness predicts intra-family fish richness, while simultaneously integrating a striking aspect of reef ecosystems—coral hue. To do so, we quantified the coral richness, coral hue diversity, and species richness within 25 fish families in 74 global ecoregions. We then expanded this to an analysis of all reef fishes (4465 species). Considering coral bleaching as a natural experiment, we subsequently examined hue's contribution to fish communities. Coral species and hue diversity significantly predict each family's fish richness, with the highest correlations (> 80%) occurring in damselfish, butterflyfish, emperors and rabbitfish, lower (60–80%) in substrate-bound and mid-water taxa such as blennies, seahorses, and parrotfish, and lowest (40–60%) in sharks, morays, grunts and triggerfish. The observed trends persisted globally. Coral bleaching's homogenization of reef colouration revealed hue’s contribution to maintaining fish richness, abundance, and recruit survivorship. We propose that each additional coral species and associated hue provide added ecological opportunities (e.g. camouflage, background contrast for intraspecific display), facilitating the evolution and co-existence of diverse fish assemblages.

Coral reef ecosystems are at the forefront of biodiversity loss and climate change-mediated transformations. This is expected to have profound consequences for the functioning of these ecosystems. However, assessments of ecosystem function on reefs are often spatially limited, within biogeographic realms, or rely on presumed proxies such as traits. To address these shortcomings and assess the effects of biogeography and fish presence on the critical ecosystem function of macroalgal removal, we used assays of six algal genera across three reef habitats in two biogeographically distinct locations: Little Cayman in the Caribbean and Lizard Island on the Great Barrier Reef (GBR). Patterns of fish feeding and realised ecosystem function were strikingly similar between the two geographic locations, despite a threefold difference in the local diversity of nominally herbivorous fishes, a 2.4-fold difference in the diversity of fishes feeding and differences in the biogeographic history of the two locations. In both regions, a single species dominated the function: a surgeonfish, Naso unicornis, at the GBR location and, surprisingly, a triggerfish, Melichthys niger, at the Caribbean location. Both species, especially M. niger, were relatively rare, compared to other nominally herbivorous fishes, in censuses covering more than 14,000 m2 at each location. Our study provides novel insights into the critical function of macroalgal removal in hyperdiverse coral reef ecosystems, highlighting: (a) that function can transcend biogeographic, taxonomic and historical constraints; and (b) shortcomings in our assumptions regarding fish presence and realised ecosystem function on coral reefs.

Temperate reef fishes provide many benefits to humans including food, sport, and ecotourism, yet remain severely understudied compared to coral reef fishes in tropical environments. We used 3 years of underwater video data (n = 4130 samples) from hardbottom reefs along the continental shelf of the southeastern US Atlantic coast (i.e., North Carolina to Florida; ~ 100,000 km2) to quantify the spatial and temporal patterns of temperate reef fish biodiversity in the region. Overall, 210 taxa were identified on video from 53 families, 138 of which could be identified to the species level. Species with the highest percent occurrence were gray triggerfish (Balistes capriscus; observed on 45.6% of all videos), tomtate (Haemulon aurolineatum; 42.7%), and red porgy (Pagrus pagrus; 39.4%), and 23 species were observed on more than 10% of videos. Latitudinal variability swamped temporal changes (2015–2017) for most taxa. After accounting for the influence of water clarity and current direction on video detectability, generalized additive models suggested that species and family richness were highest at sites characterized by moderate depths, a high proportion of hardbottom, high substrate relief, and warm water. Our results can be used to predict areas of highest reef fish biodiversity at large (regional) and small (microhabitat) scales to improve marine protected area design, delineate essential fish habitats, and parameterize ecosystem models.

Two new species of Cardicola Short, 1953 (Aporocotylidae) are described from fishes from the Great Barrier Reef (GBR), Australia. Cardicola abu sp. n. infects the Whitley’s sergeant Abudefduf whitleyi Allen & Robertson (Pomacentridae), and is described from Wistari Reef of the Capricorn-Bunker Group, on the southern GBR. Cardicola yuelao sp. n. infects the halfmoon triggerfish Sufflamen chrysopterum Bloch & Schneider (Balistidae), and is described from off Lizard Island, on the far northern GBR. Morphological analysis and molecular phylogenetic analysis show both species agree with the concept of the genus Cardicola. Balistidae and Pomacentridae are new host families for Cardicola and for aporocotylids in general.

Despite high rates of photosynthetic oxygen production during the day, the warm waters of coral reefs are susceptible to hypoxia at night due to elevated respiration rates at higher temperatures that also reduce the solubility of oxygen. Hypoxia may be a challenge for coral-reef fish that hide in the reef to avoid predators at night. Triggerfishes (Balistidae) are found in a variety of reef habitats, but they also are known to find refuge in reef crevices and holes at night, which may expose them to hypoxic conditions. The critical oxygen tension (P crit) was determined as the point below which oxygen uptake could not be maintained to support standard metabolic rate (SMR) for five species of triggerfish. The triggerfishes exhibited similar levels of hypoxia tolerance as other coral-reef and coastal marine fishes that encounter low oxygen levels in their environment. Two species, Rhinecanthus rectangulus and R. aculeatus, had the lowest P crit (~ 3.0 kPa O2), comparable to the most hypoxia-tolerant obligate coral-dwelling gobies, while Odonus niger and Sufflamen bursa were moderately tolerant to hypoxia (P crit ~ 4.5 kPa), and Xanthichthys auromarginatus was intermediate (P crit ~ 3.7 kPa). These differences in P crit were not due to differences in oxygen demand, as all the species had a similar SMR once mass differences were taken into account. The results suggest that triggerfish species are adapted for different levels of hypoxia exposure during nocturnal sheltering within the reef.

Fisheries acoustics is now a standard tool for monitoring marine organisms. Another use of active-acoustics techniques is the potential to qualitatively describe fish school and seafloor characteristics or the distribution of fish density hotspots. Here, we use a geostatistical approach to describe the distribution of acoustic density hotspots within three fishing regions of the Northern Demersal Scalefish Fishery in Western Australia. This revealed a patchy distribution of hotspots within the three regions, covering almost half of the total areas. Energetic, geometric and bathymetric descriptors of acoustically identified fish schools were clustered using robust sparse k-means clustering with a Clest algorithm to determine the ideal number of clusters. Identified clusters were mainly defined by the energetic component of the school. Seabed descriptors considered were depth, roughness, first bottom length, maximum Sv, kurtosis, skewness and bottom rise time. The ideal number of bottom clusters (maximisation rule with D-Index, Hubert Score and Weighted Sum of Squares), following the majority rule, was three. Cluster 1 (mainly driven by depth) was the sole type present in Region 1, Cluster 2 (mainly driven by roughness and maximum Sv) dominated Region 3, while Region 2 was split up almost equally between Cluster 2 and 3. Detection of indicator species for the three seabed clusters revealed that the selected clusters could be related to biological information. Goldband snapper and miscellaneous fish were indicators for Cluster 1; Cods, Lethrinids, Red Emperor and other Lutjanids were linked with Cluster 2, while Rankin Cod and Triggerfish were indicators for Cluster 3.

This study provides the first documented incidence of aquarium-based introduction of exotic fishes into the Red Sea, in the Coral Beach Nature Reserve in Eilat, Israel. A clown triggerfish Balistoides conspicillum and a queen angelfish Holacanthus ciliaris were sighted inside the marine protected area, then captured and examined, and Photobacterium damselae ssp. piscicida was isolated from the kidney of H. ciliaris. This is the causative agent of “fish pasteurellosis”, which has been responsible for massive kills in natural fish populations. The finding of this pathogen in the angelfish is worrisome, and exemplifies the concerns associated with the introduction of non-indigenous fish together with unwanted pathogens. Our findings underscore the vital importance of raising public awareness against such practices in order to curb future ecological impairment of this biologically fragile natural habitat.

Coral recruitment and juvenile growth are essential processes for coral population maintenance and recovery. A growing body of research has evaluated the influence of reef microstructure on coral settlement and post-settlement survival, showing that physical refugia enhance recruitment. These studies have evaluated coral recruit morality from competition with macroalgae and indirect predation by grazing organisms, but the impact of direct predation by corallivorous piscine species on juvenile corals and how this interacts with reef microstructure is relatively unknown. This study examined whether refugia provided by micro-crevices enhance juvenile coral survival from corallivory. Juvenile corals from two different functional groups, the slow-growing massive Porites lobata and fast-growing branching Pocillopora damicornis, with average nubbin sizes of 1.4 cm × 0.3 cm and 0.5 cm × 1.0 cm (diameter × height), respectively, were attached to experimental tiles using small (1.44 cm3) and large (8.0 cm3) crevice sizes and were monitored for 29 d on a forereef in Palau. Full crevices (four sided) enhanced coral survival compared to exposed microhabitats in both coral taxa, but crevice size did not alter survival rates. Corallivores targeted recruits within crevices regardless of crevice size; dominant predators included small triggerfish (Balistidae), butterflyfish (Chaetodon), and wrasse (Cheilinus). Overall, Pocillopora suffered much higher rates of mortality than Porites. All Pocillopora were consumed by day 8 of the experiment, but mortality was significantly delayed in full crevices compared to exposed and partial crevice (three sided) microhabitats. In contrast, Por. lobata located in all microhabitats survived the entire experiment up to 29 d, with high survival in full (>90%) and partial crevices (70%), but only 28% survival in exposed microhabitats. These findings show the importance of crevices as spatial refugia from predators for juvenile corals and highlight the importance of structural complexity for juvenile coral growth and survival that enhances reef recovery.

Proteinases from liver extract from albacore tuna (Thunnus alalunga) were used to produce protein hydrolysate from starry triggerfish (Abalistes stellaris) muscle. Hydrolysis conditions for preparing protein hydrolysate from starry triggerfish muscle were optimized. Enzyme level, reaction time and fish muscle/buffer ratio significantly affected the hydrolysis (p

The arrows or lines are missing from the published Fig. 1b and Fig. 1d of this article. The correct Fig. 1 is included here. This mistake does not affect the concept or any other information provided in other parts. In addition, the results and conclusions of the paper also remain valid.

Variations in the shape of the profile of a 24-h continuous, indirect measurement of intraocular pressure with a contact lens sensor may possibly be influenced by artifacts. We examined the sensitivity of a contact lens sensor to changes in temperature that patients may experience during the measurement period. Three Triggerfish contact lens sensors (Sensimed, Lausanne, Switzerland) were placed in a container with 0.9 % physiological saline solution. The temperature of the solution was either raised with a thermostat over a period of hours, rapidly cooled with crushed ice, or allowed to cool slowly to room temperature. The temperatures were recorded with two probes; the Triggerfish profiles were shown in millivolt equivalents (mV eq). All three profiles mainly showed that the mV eq fell when the temperature increased, and rose when the temperature decreased, with a few deviations from this behavior. Rapid temperature change with ice produced pronounced spikes in the profile. The extent of change in mV eq was not uniform with slow changes in temperature but was always slight (between 0.5 and 3 mV eq per degree centigrade), though it was high with rapid cooling. Our studies with the Triggerfish contact lens sensor showed that the sensor is sensitive to temperature changes. This is not surprising because the gauge that measures strain is made of platinum and titanium, and metals possess electrical and thermal conductivity. Apparently, the temperature sensitivity is not adequately compensated by the Wheatstone bridge used. The possible temperature sensitivity should be taken into consideration in evaluating the pressure profiles.

The prevalence of a haremic mating system type with parental care is one of the main characteristics of the modern triggerfish family (Balistidae). In addition, intraspecific modifications of the mating system in relation to environmental conditions have been recognized. Thirteen months of observation of mating units in a natural population of Rhinecanthus aculeatus from Okinawa Island, Japan, revealed that the mating system in this species involved a mixture of polygyny, monogamy, and potential promiscuity in solitary females. Females defended individual, multi-purpose territories, while males engaged in female defence (“female defence polygyny”) using displays and overt aggressions that advertised that territories were occupied. Male size was strongly linked to access to multiple females (i.e. polygyny). Plasticity in the mating system was related to male–male competition and the ability of females to reject males. An increase in the proportion of monogamous pair territories over the course of the reproductive season was positively correlated with the adult sex ratio (increased male density relative to females), and facultative monogamy was enhanced under a less female-biased sex ratio. A comparison between female and male mating success (number of matings) and the adjustment of the mating status over time revealed that polygyny was advantageous and the optimal mating system for males. Females achieved higher number of matings when pairing with larger males, but mating success was not negatively affected by the actual mating status, and females did not attempt to escape polygyny. Polygyny is therefore considered as the primary mating system in R. aculeatus.

To understand age and growth of the Picasso triggerfish, Rhinecanthus aculeatus, monthly sampling was conducted from February 2010 to October 2011 on the subtropical Okinawa Island, Japan, using trammel net and speargun. Fish were measured by weight (W) and standard length (SL) and age was determined by examining thin-sections of the first dorsal spine and the second abdominal vertebra. A total of 352 fish were caught ranging from 20.9 mm to 209.5 mm (SL). Marginal increment analysis indicated that translucent rings were deposited annually during the colder season from October to January. The relationship of observed SL and age was described by the original form of the von Bertalanffy growth equation. Male and female growth models were significantly different. Overall growth was rapid during the first 2.5 years for both sexes, thereafter growth curves diverged. Males consequently reached larger sizes and greater ages. Maximum age for males and females was 13.5 and 9.5 years, respectively. Regression models of somatic growth (SL) as a function of vertebral and spine radii were significantly correlated (r = 0.98 and r = 0.96, respectively). According to the weight–length relationship, growth in R. aculeatus was negative allometric. Small recruits (SL

The spiny lobster, Panulirus argus, is predominantly nocturnal, remaining inside shelters during the day and foraging outside at night, presumably to minimize predation risk. Predation risk generally decreases with increasing lobster size. Therefore, this study examined the hypothesis that size would influence this basic circadian pattern. Video cameras continuously recorded the shelter occupancy of juvenile lobsters (n = 72) having a carapace length (CL) of 30–62 mm that were tethered to shelters in a shallow reef lagoon. The lobsters’ shelter occupancy was 100% during the day, but declined linearly from shortly before sunset to a minimum of 50% shortly after midnight and then increased linearly, reaching 100% by 1 h after sunrise. The percent time the lobsters spent in the shelters followed a similar trend, but there was wide variability at night (0–100%) for individual lobsters. Lobsters left their shelters 2–30 times night−1, with a majority of excursions lasting 80 mm CL), which have a dusk/early evening peak in activity and leave the shelter for extended periods of time during the night. Furthermore, a minimum shelter occupancy in the middle of the night appears especially well adapted to avoid exposure to daytime predators. Videotaped observations also included interactions between lobsters and two dominant lobster predators, the triggerfish, Balistes capriscus, and the octopus Octopus cf. vulgaris. Lobsters responded differently to these predators: remaining in the shelter when attacked by a triggerfish and fleeing the shelter when attacked by an octopus. Triggerfish were nearly twice as likely to attack a lobster that was outside of the shelter than inside. Once under attack, however, a lobster had nearly the same chance of surviving if it was inside or outside. Results suggest that the patterns of shelter use and emergence change as lobsters grow, probably reflecting the interplay between perception of predation risk and the need to forage.

The remarkable swarming of black triggerfish Melichthys niger (Balistidae) on oceanic islands led us to undertake a comparative ecological study of high-density and low-density populations of this unusual circumtropical species. Abundance, distribution, and aggressive encounters were recorded in the field from the high-density Johnston Atoll (JA) population, the low-density Belize (BE) population, and a local high-density aggregation from Puerto Rico (PR). JA and PR populations of M. niger occurred at significantly higher densities and were more aggregated than in BE. Intraspecific aggression (chases/min/fish) was an order of magnitude higher in BE than in JA, while interspecific aggression was similar among sites. Size frequency, growth rate, diet composition, body condition (liver-somatic index LSI) were assessed from collected specimens. JA grew more slowly than BE as determined by back-calculations from dorsal spine rings, suggesting density-dependent growth limitation. Size frequency analysis reflected this difference with significantly more large fish in the BE sample. Maximum age of triggerfish in both populations was estimated at 11 years, and 35–40% of growth occurred in the first year. Diet composition was similar in all three locations and indicated broad omnivory. Percent organic composition of gut contents (food quality measure) and LSI (body condition assay) were both significantly higher in the PR population, but no difference was detected between JA and BE. An increase in consumption of algae on the degraded PR reef may explain this pattern.

The congeneric spiny lobsters Panulirus argus and P. guttatus co-occur throughout the Caribbean Sea, where they may share the coral reef habitat. Despite their phylogenetic closeness, both species have many different life-history traits that may partially explain their coexistence. However, even though both species may face the same predators, their defense mechanisms and antipredator strategies had not been compared. We compared the performance between species in 18 morphological and behavioral defense mechanisms commonly expressed by most spiny lobsters, including predator-avoidance mechanisms (activity schedule, sheltering behavior, delay to disturbance, and effect of conspecific damage-released scents on shelter choice) as well as antipredator mechanisms (body size, several parameters of the escape response and limb autospasy, clinging strength, antennal strength, and cooperative defense). As hypothesized, both species expressed all these defense mechanisms (except cooperative defense, shown only by P. argus), reflecting their phylogenetic closeness, but performed significantly differently in most, in accordance with their particular ontogenetic traits. Their comparative performance in individual defense mechanisms as well as the antipredator strategies displayed by groups of lobsters of each species in the presence of a common predator (the triggerfish Balistes vetula) showed that, in general, the defensive behavioral type of P. argus is more bold and that of P. guttatus more shy. Therefore, their distinct defensive behaviors contribute to their niche differentiation.

Eight polymorphic microsatellites in the gray triggerfish, Balistes capriscus, are presented. For 24 genotyped individuals, the number of observed alleles per locus ranged from 10 to 21 (mean = 15), and observed heterozygosity varied between 0.708 and 1.000. Genotypic frequencies did not deviate significantly from Hardy–Weinberg equilibrium proportions, and there was no evidence of null alleles or linkage disequilibrium among loci. These microsatellite loci are additional markers for fisheries managers to utilize in population-level B. capriscus assessments.

Reproductive ecology of the crosshatch triggerfish, Xanthichthys mento (Balistidae) was studied at Hachijojima, Izu Islands, Japan. Males established territories and repeatedly chased females passing nearby. There were 1–3 females in each male's territory before spawning and during egg care. This species spawned in pairs on the sandy bottom. Eggs were scattered and attached to sand particles. Females care for the eggs by blowing water on them and guarding them against intruders, while males helped in guarding. Thus, biparental egg care was observed for 2 days until hatching. Both the males and females disappeared from the territories after the egg care. The reproductive ecology of this species is compared with that of other balistids and the unique features of X. mento are described.

Twenty one microsatellite markers were isolated from two enriched genomic libraries of the gray triggerfish, Balistes capriscus. The number of alleles detected varied between 4 and 27, and expected heterozygosity estimates ranged from 0.502 to 0.967 (n = 35). Genotypic proportions conformed to Hardy–Weinberg expectations for all but two of the loci. The microsatellite markers developed in this work will be precious to conservation genetics studies of the gray triggerfish.

Reproductive behavior and mating systems of the triggerfish,Sufflamen chrysopterus (Balistidae), were studied on the fringing reef of Sesoko Island, Okinawa. Both males and females maintained territories against consexual adults, feeding on benthic animals within their own territories. Each male territory overlapped one or two female territories, with mating occurring between the cohabitants. The monogamous males were smaller and foraged more frequently than the bigamous ones, suggesting that the former allocated more energy to growth rather than to improving reproductive success. Pair spawning occurred around sunrise, females only taking care of the demersal eggs until hatching, which occurred around sunset of the same day. On spawning days females foraged less frequently than usual, but as frequently as males. Females spawned at intervals of 5–7 days, usually shifting sites within their territories. Thus both feeding and spawning sites were available for females within their territories, providing males with the opportunity to monopolize females by defending their territories.

Predation on 120 adult sea urchins of the speciesEchinometra mathaei was observed during daylight in shallow-water coral reefs (0.5 to 3 m deep) in a variety of sites in 3 Kenyan marine parks. The predators were few (8 species) and dominated by the triggerfishBalistapus undulatus (65 % of all observations) followed by terminal-male wrassesCoris formosa, C. aygula andCheilinus trilobatus, and lastly the scavengerLethrinus mahsena. Those species that attempted, but failed, to prey onE. mathaei were slightly more numerous (11 species), while scavengers of opened carcasses were the most speciose (20 species). Based on these observations, it is suggested thatB. undulatus is a ‘keystone predator’ and that fishery regulations that protect this species may be necessary in order to reduce the detrimental consequences of high sea urchin abundance — such as high reef substrate erosion and competitive exclusion of fishes.

The size-advantage model predicts that protogyny is likely to evolve in polygynous species. Polygynous mating systems have been reported from several species of triggerfishes (Balistidae), but sex change has never been confirmed among them. We performed male-removal experiments in the haremic triggerfish Sufflamen chrysopterus on the coral reefs of Sesoko Island, Okinawa. After removal and movement of territorial males, some females became single and later changed body color and sex. This is the first report of sequential hermaphroditism from Tetraodontiformes.

The triggerfishPseudobalistes flavimarginatus has a lek-like spawning system at Yonge Reef, Great Barrier Reef. Males migrate to a traditional mating ground where they establish territories enclosing nest sites and egg chambers. Females arrive several days later and choose a male for mating. There is biparental care of the fertilized eggs and a strict division of labour. Females appeared to be confined to the nest site by the male. Mating was semi-lunar: eggs were observed in nests several days before the new and full moons on days when high tide occurred near sunset. Differences were observed in the spawning system of another triggerfish (P. fuscus) between the Great Barrier Reef and the Red Sea. Observations of another triggerfish (Balistoides viridescens) are also reported.

A survey of Kenya's shallow water (

Large differences in community structure of sea urchins and finfish have been observed in Kenyan reef lagoons. Differences have been attributed to removal of finfish predators through human fishing activities. This study attempted to determine (i) the major sea urchin finfish predators, (ii) the effect of predation on sea-urchin community structure, and (iii) the possible effect of sea urchin increases and finfish decreases on the lagoonal substrate. Six reefs, two protected and four unprotected, were compared for differences in finfish abundance, sea urchin abundance and diversity and substrate cover, diversity and complexity. Comparisons between protected and unprotected reefs indicated that finfish populations were ca. 4 x denser in protected than unprotected reefs. Sea urchin populations were >100 x denser and predation rates on a sea urchin, Echinometra mathaei, were 4 x lower in unprotected than in protected reefs. The balistidae (triggerfish) was the single sea-urchin finfish predator family which had a higher population density in protected than in unprotected reefs. Balistid density was positively correlated with predation rates on tethered E. mathaei (r=0.88; p

In January 1980, a severe 3 day storm struck the normally protected leeward coral reefs of Kona, Hawaii. Waves generated by the storm, which was estimated to be a once in 20–40 year occurrence, were in excess of 6 m and caused extensive reef destruction and shoreline alteration. Shallow nearshore areas were denuded of most bottom cover and marine life. Damage to corals was extensive with broken colonies of the coral Porites compressa occurring down to depths of 27 m. Pronounced algal blooms occurred in a clearly defined sequence subsequent to the storm. The patterns of both coral destruction and algal succession were similar to those described on other storm damaged reefs. Fish mortality directly attributable to the storm was slight and the few dead fishes noted were either surge zone or tide pool species. After the storm the shallow reef flat was devoid of resident fishes while deeper areas contained many fishes which had moved from shallower water. This habitat shift substantially reduced the immediate impact of the storm on the fish community. Despite considerable habitat destruction that resulted from the storm, there were no decreases in species or population abundances on five 25 m2 quadrats monitored for 23 months before and 16 months after the storm. Similarly, the numbers of triggerfish sheltering within an area increased even though the storm reduced the number of available shelter holes. The shelter and space-related carrying capacity of these areas prior to the storm may therefore not have been reached. Recolonization of evacuated areas by fishes began shortly after the storm and within 16 months many areas had regained their prestorm appearances. Large numbers of individuals remained however, in their shifted locations.

A new triggerfish,Rhinecanthus abyssus, is described from three specimens collected in the Ryukyu Islands at depths of 120–150 m. It is distinguished from the other species ofRhine-canthus by the combination of the following characters: soft dorsal rays 22–23, soft anal rays 20, a large black blotch around anus, and no semicircular white band on posterior side of body.

Ten blue triggerfish,Balistes fuscus, were tested individually for 3 days each in Ichthyotron electronic shuttleboxes to measure their thermoregulatory behavior. The modal thermal preferendum, a species-specific measure of temperature preference which is independent of prior thermal acclimation, was 25 °C. The triggerfish voluntarily occupied a 16–27 °C range of temperature, out of a potentially available range of 0–50 °C. There was no significant difference in preferred temperature between night and day, indicating lack of a thermoregulatory rhythm in this species. The preferred temperature range of this tropical marine reef species is similar to that of cool temperate freshwater and marine fishes; many warm temperate species prefer higher temperatures.