Plectropomus Leopardus Research Articles

Swim for it: Effects of simulated fisheries capture on the post-release behaviour of four Great Barrier Reef fishes

After being caught and released by a fishery, some animals may be sufficiently impaired so as to be vulnerable to predators. The duration and severity of post-release impairments have rarely been studied under natural conditions; the vitality of animals is usually assessed aboard a vessel, prior to release, while examinations of post-release behaviour are usually restricted to what is within view of a vessel. In this study, we quantified the post-release behavior of the common coral trout (Plectropomus leopardus), two species of emperor (Lethrinus spp.), and the Spanish flag snapper (Lutjanus carponotatus), each of which is actively fished throughout the Great Barrier Reef. SCUBA divers followed fish in the field and recorded their behavior with underwater video cameras after a simulated catch-and-release event. Relative to a low stress treatment (held in an aerated tank prior to release), fish exposed to forced exercise and 5 min of air exposure spent more time in vulnerable positions after release, including 5.8× more time immobile under the boat upon release, 1.6× more time to reach the reef floor, and 2.4× longer to reach the protection of the reef. The effects of the catch-and-release simulation on tailbeat frequency, ventilation rate, and the proportion of overall time spent immobile were not significant except in L. carponotatus, which spent significantly more time immobile when exposed to the high stress treatment. Indeed, there were some notable differences among species, with the magnitude of the behavioural impairments being lower and less variable in coral trout than in Lethrinus spp. or L. carponotatus. These findings provide support for the notion that minimizing air exposure time in hook-and-line fisheries should reduce post-release behavioural impairments and thus vulnerability to predators.

Effects of dietary Spirulina platensis on growth performance, hematological and serum biochemical parameters, hepatic antioxidant status, immune responses and disease resistance of Coral trout Plectropomus leopardus (Lacepede, 1802)

The present study investigated the effects of dietary Spirulina platensis supplementation on growth performance, hematological and serum biochemical parameters, hepatic antioxidant status, immune responses and resistance to the pathogen infection in Coral trout Plectropomus leopardus. The fish were fed for 8-week with diets containing different levels of S. platensis: 0% (C), 2% (SP2), 4% (SP4), 6% (SP6), 8% (SP8) and 10% (SP10) as treatment groups, followed by a Vibrio harveyi infection test for 14 d. The study indicated that dietary supplementation with Spirulina platensis could significantly improve growth performance, and the highest weight gain rate (WGR) and specific growth rate (SGR) were observed in group SP10 (P < .05). Red cell count (RBC), white cell count (WBC), hemoglobin (Hb) and total antioxidant capacity (T-AOC) in the S. platensis supplemented groups were significantly higher than those of group C (P < .05). However, the levels of cholesterol, triglyceride and malondialdehyde (MDA) contents, and superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) activities decreased with the increasing of dietary S. platensis levels. Compared with group C, the lysozyme (LYZ) and respiratory burst activities (RBA), and immunoglobulin (Ig) and complement contents in group SP4, SP6, SP8 and SP10 increased significantly than those of group C respectively (P < .05). After challenge with V. harveyi, the survival rate in group SP4, SP6, SP8 and SP10 was significantly higher than that of group C, and the highest survival rate was in group SP10 (P < .05). These results indicated that P. leopardus fed a diet supplemented with S. platensis (especially at 10%) could significantly promote its growth performance, improve its hepatic antioxidant status, and enhance its immune ability and resistance to V. harveyi infection.

GROWTH AND BLOOD PROFILE OF CORAL TROUT GROUPER Plectropomus leopardus SEEDS IN DIFFERENT SALINITIES

The information about the optimum and tolerable salinity to support in the success of coral trout grouper’s seed culture is still limited until now. The aim of this study was to understand the effect of different salinity on growth, survival, feed conversion (FCR) and the profile of blood (hematocrit and hemoglobin) of coral trout grouper seed. The seed with total length 6.0 ± 0.5 cm and body weight 3.2±0.3 g were used as tested animals. Five different salinity treatments, namely: 10±1 ppt (A), 16±1 ppt (B), 22±1 ppt (C), 28±1 ppt (D), and the sea water (34 ppt) as a control (E) were undertaken in this study, with three replications for each treatment. Salinity values were reach by adding freshwater into the tested seawater. Water changing system in this study was performed in recirculation process, with 25% of water replacement every 7 days. The result of this study showed that the survival rate values were 100% for all treatments, indicating that coral trout grouper seed can be cultured in the range of salinity between 10 to 34 ppt. The highest total length and body weight were recorded from treatment C (22 ppt), as well as noted to gain the lowest FCR. Correspondingly, the seed in treatment C also founded to have in the greatest amount of hematocrit and hemoglobin. Optimum salinity for rearing of coral trout grouper seeds with total length 6 cm was 22 ppt. Keywords: salinity, growth, survival rate, feed conversion, blood profile

The Benefit of Decision Support System as Sustainable Environment Technology to Utilize Coastal Abundant Resources in Indonesia

Being the largest archipelagic state in the world (± 81 000 km of coastline), Indonesia has a great potential for developing the aquaculture industry. But, the accomplishment of sustainable practices and management systems are still in its infancy. Therefore, it is vital to improve aquaculture technology and develop management tools that address the need for an eco-friendly production process. In this manuscript, the Decision Support System software is applied for the management of sustainable floating net cage finfish cultures. This software integrates physical, chemical, biological properties and information on coastal uses to determine site selection, production carrying capacity, ecological carrying capacity and socio-economic assessment of 18 cases, focusing on the economic viability of Tiger grouper [Epinephelus fuscoguttatus (Forsskål, 1775)], Humpback grouper [Cromoliptes altivelis (Valenciennes, 1828)] and Leopard Coral grouper [Plectropomeus leopardus (Lacepède, 1802)] at three remote areas in Indonesia, including: Ekas Bay, Talise and Galang Island. The outcomes demonstrate that only Galang Island provides a suitable area of 12 940 ha with the estimated production carrying capacity of (0.5 to 366) t/annual per fish farm along with ecological carrying capacity are limited of (18 393 to 21 727) t/annual and economic evaluation highlighted that all cultures development are economically viable.

Emergence of serranid pigment abnormality syndrome (SPAS) in wire netting cod (Epinephelus quoyanus) from Heron Island on the southern Great Barrier Reef

Coral reefs worldwide are under increasing stress from anthropogenic impacts, but there are relatively few reports of increased rates of disease in coral reef fish. Herein we report the emergence of abnormal skin lesions in wild-caught wire netting cod (Epinephelus quoyanus) near Heron Island in the southern Great Barrier Reef. The lesion involves conspicuous darkening and disorganisation of the brown ‘wire netting’ colouration pattern typical of this species, most commonly on the lower jaw, premaxilla and head, with occasional involvement of the flanks and dorsal fin in some fish. The lesion was not present during research conducted in the mid-1990s; however, since it was first recorded in 2012, the prevalence of grossly visible lesions has increased to 16.9% in 2017, with fish &gt;340mm long most affected (prevalence 64.7%). These data suggest emergence of the lesion is a recent phenomenon and that causative factors may be age related. Abnormal pigmentation lesions have only been observed to affect E. quoyanus and coral trout (Plectropomus leopardus; since 2010). Given the species affected and the currently unknown aetiology of these lesions, we name the condition serranid pigment abnormality syndrome (SPAS). Further research is required to determine its geographic distribution, establish causation and describe the course of disease in E. quoyanus.

Participatory Boat Tracking Reveals Spatial Fishing Patterns in an Indonesian Artisanal Fishery

The Spermonde Archipelago holds one of the largest artisanal fisheries in Indonesia, providing livelihoods for local communities and many other people involved in international trade networks of seafood. High demand and a lack of enforcement of existing fisheries regulations turn into high pressure for the coral reef ecosystem, contributing to its overall degradation. Estimations on the ecological impacts of different levels of fishing pressure, as well as fisheries stock assessments and marine resource management require precise information of the spatial distribution of fishing effort, which involves great uncertainty when only anecdotal information is considered. We explored the feasibility of applying participatory boat tracking to complement fisheries data during the NW monsoon season 2014-2015. We conducted interviews, measured catch landings and distributed GPS data loggers among hook and line fishermen to identify fishing grounds by gear-dependent patterns of boat movement. Most of the fishing activities involved two gears (octopus bait and trolling line for live groupers) and three fishing grounds. The mass of catch landings was dominated by Octopoda (CPUE=10.1 kg boatday-1) while the most diverse group was the fish family Serranidae, with Plectropomus leopardus being the main target species. In conclusion, boat tracking combined with interviews and catch surveys has proven a useful tool to reduce uncertainty in information on spatial resource use, while allowing a high level of participation by fishermen.

Development of a validation protocol of enzyme immunoassay kits used for the analysis of steroid hormones in fish plasma

The analysis of steroid hormones 17β-estradiol, testosterone and 11-ketotestosterone in fish plasma provide insight into fish reproductive behavior and development. Typically, steroid hormones are analyzed using gold standard approaches, such as radioimmunoassay and liquid chromatography coupled with tandem mass spectrometry. However, these methods are not always available to small-to-medium research facilities due to their large capital outlay, expensive running costs and ongoing maintenance needs, in addition to requiring a costly radioisotope license and skilled staff to handle and perform the assays. One approach being increasingly used by researchers is commercial enzyme immunoassay (EIA) kits (also known as ELISA kits), analyzed with the use of a UV–vis spectrometer. However, with their increased use, many studies fail to validate their EIA kits or fail to report on the kits sensitivity, accuracy and precision. As such, the aim of this paper is to propose a standardized protocol for reporting EIA kit validation. The proposed protocol was then applied to three fish species in order to demonstrate parallelism, accuracy and precision. Specifically, we tested plasma concentrations of 17β-estradiol for the red and black anemonefish Amphiprion melanopus, and 17β-estradiol, testosterone and 11-keto-testosterone for the barramundi Lates calcarifer and the common coral trout Plectropomus leopardus. Steroid hormones were extracted from fish plasma using a liquid-liquid solvent extraction method with ethyl acetate and n-hexane (50:50 v:v). Following extraction, the plasma dilution curves showed good linearity and parallelism, steroid recoveries were found to be within 90–120% accuracy, and precision variance was <10% in the majority of assays, for the species and steroids measured. Utilization of the proposed standardized validation protocol of EIA kits will assist scientific, fisheries and aquaculture researchers in obtaining reliable steroid hormone measurements, particularly in the field and in smaller research laboratories.

Exploring the effect of sampling, protogyny, and larval advection on stock estimates subject to no-take closures in a spatially complex coral reef line fishery on the Great Barrier Reef, Australia

Simulation is used to evaluate the ability of a two-region, age-structured assessment model to provide accurate and precise estimates of stock status (i.e., the ratio of female spawning biomass to unfished female spawning biomass) for coral trout (Plectropomus leopardus) on the Great Barrier Reef (GBR), Australia. The model used to generate the simulated data used by the assessment model is a spatially complex age- and sex-structured population dynamics model that captures the protogynous nature of coral trout. Stock status is underestimated (negatively biased), with the extent of negative bias related to mis-specification of the breeding strategy of the target fish stock, the impact of the amount of larval connectivity among reefs, the number of reefs closed to fishing, as well as exploitation rates. The estimates of stock status were less negatively biased when fishery-independent index and age- and length-composition data were available from closed areas. The results will inform the development of management strategies for coral trout in the GBR and highlight the importance of basing evaluations of estimation and management performance on operating models that capture ecologically important processes such as metapopulation dynamics and protogynous life history.

A large predatory reef fish species moderates feeding and activity patterns in response to seasonal and latitudinal temperature variation

Climate-driven increases in ocean temperatures are expected to affect the metabolic requirements of marine species substantially. To mitigate the impacts of increasing temperatures in the short-term, it may be necessary for ectothermic organisms to alter their foraging behaviour and activity. Herein, we investigate seasonal variation in foraging behaviour and activity of latitudinally distinct populations of a large coral reef predator, the common coral trout, Plectropomus leopardus, from the Great Barrier Reef, Australia. P. leopardus exhibited increased foraging frequency in summer versus winter time, irrespective of latitude, however, foraging frequency substantially declined at water temperatures >30 °C. Foraging frequency also decreased with body size but there was no interaction with temperature. Activity patterns were directly correlated with water temperature; during summer, the low-latitude population of P. leopardus spent up to 62% of their time inactive, compared with 43% for the high-latitude population. The impact of water temperature on activity patterns was greatest for larger individuals. These results show that P. leopardus moderate their foraging behaviour and activity according to changes in ambient temperatures. It seems likely that increasing ocean temperatures may impose significant constraints on the capacity of large-bodied fishes to obtain sufficient prey resources while simultaneously conserving energy.

Widespread hybridization and bidirectional introgression in sympatric species of coral reef fish.

Coral reefs are highly diverse ecosystems, where numerous closely related species often coexist. How new species arise and are maintained in these high geneflow environments have been long-standing conundrums. Hybridization and patterns of introgression between sympatric species provide a unique insight into the mechanisms of speciation and the maintenance of species boundaries. In this study, we investigate the extent of hybridization between two closely related species of coral reef fish: the common coral trout (Plectropomus leopardus) and the bar-cheek coral trout (Plectropomus maculatus). Using a complementary set of 25 microsatellite loci, we distinguish pure genotype classes from first- and later-generation hybrids, identifying 124 interspecific hybrids from a collection of 2,991 coral trout sampled in inshore and mid-shelf reefs of the southern Great Barrier Reef. Hybrids were ubiquitous among reefs, fertile and spanned multiple generations suggesting both ecological and evolutionary processes are acting to maintain species barriers. We elaborate on these finding to investigate the extent of genomic introgression and admixture from 2,271 SNP loci recovered from a ddRAD library of pure and hybrid individuals. An analysis of genomic clines on recovered loci indicates that 261 SNP loci deviate from a model of neutral introgression, of which 132 indicate a pattern of introgression consistent with selection favouring both hybrid and parental genotypes. Our findings indicate genome-wide, bidirectional introgression between two sympatric species of coral reef fishes and provide further support to a growing body of evidence for the role of hybridization in the evolution of coral reef fishes.

Economic spillovers in spatial harvest behavior

There has been a strong push within natural resource management to incorporate spatial structure into management regimes. However, discussions surrounding the appropriate designs of spatial management have largely been conceptual. This paper develops a spatial econometric model of fishing location choice using non-confidential data from the Great Barrier Reef coral trout commercial fishery. Harvest location decisions are modeled as a function of spatial patterns of expected economic returns. The preferred spatially dependent econometric model is shown to outperform ordinary least squares and fixed effects models in out-of-sample forecasting. Estimates from the spatial model reveal spatial spillover effects in fleet harvest location behavior. In particular, harvest activity at any given site is equally sensitive to same-site economic returns and surrounding-site economic returns. The econometric results are illustrated using a fee-based policy simulation. Results suggest non-spatial management is characterized by two inefficiencies. First, heterogeneity between sites is averaged, resulting a fee that is too high or too low across space. Second, fees that are too high or too low affect the fishing effort in nearby locations.

Reproductive benefits of no-take marine reserves vary with region for an exploited coral reef fish

No-take marine reserves (NTMRs) are expected to benefit fisheries via the net export of eggs and larvae (recruitment subsidy) from reserves to adjacent fished areas. Quantifying egg production is the first step in evaluating recruitment subsidy potential. We calculated annual egg production per unit area (EPUA) from 2004 to 2013 for the commercially important common coral trout, Plectropomus leopardus, on fished and NTMR reefs throughout the Great Barrier Reef (GBR), Australia. Geographic region, NTMR status, fish size, and population density were all found to affect EPUA. The interactions among these factors were such that, EPUA on NTMR reefs compared to reefs open to fishing was 21% greater in the southern GBR, 152% greater in the central GBR, but 56% less in the northern GBR. The results show that while NTMRs can potentially provide a substantial recruitment subsidy (central GBR reefs), they may provide a far smaller subsidy (southern GBR), or serve as recruitment sinks (northern GBR) for the same species in nearby locations where demographic rates differ. This study highlights the importance of considering spatial variation in EPUA when assessing locations of NTMRs if recruitment subsidy is expected from them.

Trans-omics approaches used to characterise fish nutritional biorhythms in leopard coral grouper (Plectropomus leopardus)

Aquaculture is now a major supplier of fish, and has the potential to be a major source of protein in the future. Leopard coral groupers are traded in Asian markets as superior fish, and production via aquaculture has commenced. As feeding efficiency is of great concern in aquaculture, we sought to examine the metabolism of leopard coral groupers using trans-omics approaches. Metabolic mechanisms were comprehensively analysed using transcriptomic and metabolomic techniques. This study focused on the dynamics of muscular metabolites and gene expression. The omics data were discussed in light of circadian rhythms and fasting/feeding. The obtained data suggest that branched-chain amino acids played a role in energy generation in the fish muscle tissues during fasting. Moreover, glycolysis, TCA cycles, and purine metabolic substances exhibited circadian patterns, and gene expression also varied. This study is the first step to understanding the metabolic mechanisms of the leopard coral grouper.

Identification of Plectropomus leopardus, Promicrops lanceolatus and Cromileptes altivelis using species-specific TaqMan real-time PCR

Plectropomus leopardus, Promicrops lanceolatus and Cromileptes altivelis are high-value groupers in chinese aquatic product market and are substituted by cheaper ones sometimes due to economic profit. In this study, real-time PCR methods for identification of these groupers were developed. Species-specific primers and probes were designed on the basis of cytochrome oxidase I (COI) mitochondrial DNA sequences of groupers and other fishes. The specificity of the real time PCR assays were tested with a total of 51 specimens of fish, meat and poultry. Amplifications were observed in specific species only. The methods developed were accurate and rapid and offered the potential to detect fraudulent or unintentional mislabeling of these species in routine seafood authentication analysis.

Disruptive colouration in reef fish: does matching the background reduce predation risk?

Animals use disruptive colouration to prevent detection or recognition by potential predators or prey. Highly contrasting elements within colour patterns, including vertical or horizontal bars, are thought to be effective at distracting attention away from body form and reducing detection likelihood. However, it is unclear whether such patterns need to be a good match to the spatial characteristics of the background to gain cryptic benefits. We tested this hypothesis using the iconic vertically barred humbug damselfish, Dascyllus aruanus (Linneaus 1758), a small reef fish that lives among the finger-like projections of branching coral colonies. Using behavioural experiments, we demonstrated that the spatial frequency of the humbug pattern does not need to exactly match the spatial frequency of the coral background to reduce the likelihood of being attacked by two typical reef fish predators: slingjaw wrasse, Epibulus insidiator (Pallas 1770), and coral trout, Plectropomus leopardus (Lacépède 1802). Indeed, backgrounds with a slightly higher spatial frequency than the humbug body pattern provided more protection from predation than well-matched backgrounds. These results were consistent for both predator species, despite differences in their mode of foraging and visual acuity, which was measured using anatomical techniques. We also showed that a slight mismatch in the orientation of the vertical bars did not increase the chances of detection. However, the likelihood of attack did increase significantly when the bars were perpendicular to the background. Our results provide evidence that fish camouflage is more complex than it initially appears, with likely many factors influencing the detection likelihood of prey by relevant predators.

REPRODUCTION PERFORMANCE OF WILD BROODSTOCK CORAL TROUT (Plectropomus leopardus)

Coral trout is an important export commodity in many countries in southeast Asia. In Indonesia, the export of grouper currently relies on capture fisheries. To ensure sustainability of the wild catch as well as to develope mariculture, we need to better understand the performance of wild broodstock.

Growth and mortality rate of the Napan-Yaur Coral Trout, Plectropomus leopardus (Pisces: Serranidae), Cenderawasih Bay National Park, Indonesia

Bawole R, Rahayu M, Rembet UNWJ, Ananta AS, Runtuboi F, Sala R. 2017. Growth and mortality rate of the Napan-Yaur Coral Trout, Plectropomus leopardus (Pisces: Serranidae), Cenderawasih Bay National Park, Indonesia. Biodiversitas 18: 758-764. Coral trout, Plectropomus leopardus, is one of the important fishery resources in Cenderawasih Bay National Park, Papua, Indonesia. The catch production of this species has declined since 2015. This study aims to assess growth, mortality, and exploitation rate parameters of P. leopardus taken from Napan Yaur water, Cenderawasih Bay National Park (CBNP), Indonesia. The data were collected during periods of February to March 2016. Growth and mortality parameters were analyzed using von Bertalanffy method. Some fish samples used in this study was 123 individuals, with the average length of 32.34 ± 5.13 cm, the maximum length of 48.00 cm and minimum length of 24.5 cm. The von Bertalanffy analysis showed that the growth coefficient (K) was 0.34 year-1, L∞ was 47.78 cm and t0 was-0.09 year-1. The estimation of total mortality (Z) was 1.61 year-1, natural mortality (M) was 0,75year-1 for fishing mortality (F) was 0.86 year-1, and exploitation rate (E) was 0.53 year-1. The results indicated that most P. leopardus caught were at the pre-maturity size (age) and have been exploited at slightly above its optimum exploitation level. Nevertheless, P. leopardus is categorized as fast growing and long-lived fish species. These findings are important to fisheries management and conservation authorities to fish exploitation in the future.

OPTIMIZATION OF THE FORMULATED FEEDING IN JUVENILE CORAL TROUT, Plectropomus leopardus IN CONTROLLED TANK

&lt;em&gt;&lt;span lang="EN"&gt;A coral trout grouper is the fishery commodities to generate foreign exchange through exports, to date cultivation continued. The purpose is to obtain data and information on the dose of the right artificial feeding and can increase the survival rate of the optimum seed nursery in the juvenile coral trout in controlled tank. Research has been conducted at the hatchery and the Institute for Mariculture Reasearch and Development Gondol, Bali. Containers experiment is used is a fiber with a size of 1 m³ up to 12 containers. &lt;/span&gt;&lt;span lang="IN"&gt;t&lt;/span&gt;&lt;span lang="EN"&gt;est animals used were seeds of coral trout, &lt;/span&gt;&lt;span&gt;Plectropomus leopardus&lt;/span&gt;&lt;span lang="EN"&gt; with initial body length on average 3 cm with each treatment density of 100 fish/m³. Coral trout, &lt;/span&gt;&lt;span&gt;Plectropomus leopardus&lt;/span&gt;&lt;span lang="EN"&gt; seed kept in fibers. This type of feed given in the form of commercial pellet feed with a protein content of 48%, and additional food such as shrimp Mysid (jembret) for 10 days. The frequency of feeding 3 times a day (morning 8:00. local time, lunch 13:00 local time, and afternoon 17:00 local time). Treatment feeding attempted is the treatment of A = 5% dose of artificial feeding, B = 10% dose of artificial feeding, C = 15% dose of artificial feeding, and D = 20% dose of artificial feeding. The study used a completely randomized design with 4 treatments, each treatment was repeated 3 times. Data were analyzed by analysis of variance. If the variance is different then conducted a further test using the smallest real difference test (BNT). The results showed that significantly different (P &amp;lt;0.05) on survival, feed conversion, weight gain and body length of coral trout. The highest survival rate in treatment C = 15% dose artificial feeding is. = 90.83 ± 1.80%, followed by treatment D, B, and A.&lt;/span&gt;&lt;/em&gt;

OPTIMIZATION OF THE FORMULATED FEEDING IN JUVENILE CORAL TROUT, Plectropomus leopardus IN CONTROLLED TANK

A coral trout grouper is the fishery commodities to generate foreign exchange through exports, to date cultivation continued. The purpose is to obtain data and information on the dose of the right artificial feeding and can increase the survival rate of the optimum seed nursery in the juvenile coral trout in controlled tank. Research has been conducted at the hatchery and the Institute for Mariculture Reasearch and Development Gondol, Bali. Containers experiment is used is a fiber with a size of 1 m³ up to 12 containers. test animals used were seeds of coral trout, Plectropomus leopardus with initial body length on average 3 cm with each treatment density of 100 fish/m³. Coral trout, Plectropomus leopardus seed kept in fibers. This type of feed given in the form of commercial pellet feed with a protein content of 48%, and additional food such as shrimp Mysid (jembret) for 10 days. The frequency of feeding 3 times a day (morning 8:00. local time, lunch 13:00 local time, and afternoon 17:00 local time). Treatment feeding attempted is the treatment of A = 5% dose of artificial feeding, B = 10% dose of artificial feeding, C = 15% dose of artificial feeding, and D = 20% dose of artificial feeding. The study used a completely randomized design with 4 treatments, each treatment was repeated 3 times. Data were analyzed by analysis of variance. If the variance is different then conducted a further test using the smallest real difference test (BNT). The results showed that significantly different (P &lt;0.05) on survival, feed conversion, weight gain and body length of coral trout. The highest survival rate in treatment C = 15% dose artificial feeding is. = 90.83 ± 1.80%, followed by treatment D, B, and A.

GROW OUT CULTURE OF CORAL TROUT Plectropomu leopardus IN FLOATING NET CAGES WITH DIFFERENT FEEDING FREQUENCIES

A study on the effect of feeding frequency on coral trout culture Plectropomus leopardus was conducted in floating net cages. The aim of this study was to determine an optimum feeding frequency for better growth rate and feed conversion ratio. The experiment was divided into two stages, i.e.; using fish with a range of body weight of 24 to 100 g (1st stage), and fish with a range of 100 to150 g (2nd stage). The first stage, consisted of four treatments of feeding frequencies, i.e. four times a day (4/1), three times a day (3/1), twice a day (2/1), and once a day (1/1). For the second stage experiment, the treatments applied were, three times a day (3/1), twice a day (2/1), once a day (1/1), and once in two days (1/2). Each treatment was in triplicate. At each feeding time, experimental fish were fed with dry pellets to apparent satiation. Both first and second experimental stages showed that the treatments of twice a day (2/1) feeding frequency attained significantly higher growth rates and lower feed conversion ratios than other treatments (P&lt;0.05). Survival rate at the first stage (4/1), three times a day (3/1), twice a day (2/1), higher than (1/1) (P&lt;0.05). But in the second stage the survival rate is not significant. The most optimum feeding frequencies for this species is 2/1 for the fish of 24 to 150 g BW.