Tropical Waters Research Articles

On the north equatorial current spatiotemporal modes and responses in the western boundary currents

The North Equatorial Current (NEC) and western boundary currents (WBCs) of the Kuroshio Current (KC) and the Mindanao Current (MC) characterize the circulation pattern and water mass transports in the tropical western North Pacific. We utilized the validated three-dimensional and time-dependent China Sea Multi-scale Ocean Modeling System to investigate the variability of the WBCs and the physical processes linked with the upstream NEC and associated with the circulation. The latitude-dependent KC and MC strengthen downstream from the NEC bifurcation (NB) and are maintained by the northern and southern parts of the NEC, respectively. By effectively isolating the NEC spatiotemporal modes representing its intensity, meridional migration, and bifurcation location, we investigate the responses of the WBCs to the characteristics in an integrated NEC-WBCs current system. The NEC intensity peaks in spring and summer, while its bifurcation location strongly correlates with its migration. The southward (northward) NEC migration during early spring (late autumn) feeds more NEC waters to the MC (KC). Yet, the simultaneous southward (northward) shifting NB distributes more NEC waters to the KC (MC) and offset the contribution of the migration. Thus, the intensity of the KC (MC) is primarily controlled by the NEC intensity, reaching the maximum during spring (summer). The specific water masses such as the North Pacific Tropical Water and the Equatorial Surface Water, are bounded by the time-dependent NB, distributing northward and southward respectively through the WBCs. By resolving spatiotemporal modes in NEC-KC-MC, the study provides a new understanding to the WBCs in the NEC-WBCs current system.

Biochemical and Toxinological Characterization of Venom from Macrorhynchia philippina (Cnidaria, Hydrozoa)

Macrorhynchia philippina is a colonial benthic hydroid from the Class Hydrozoa (Phylum Cnidaria) distributed in the tropical and subtropical marine waters from Atlantic Ocean, Indo-Pacific, and Mozambique. Its colonies somewhat resemble plants, causing confusion in the bathers who accidentally touch the animal. Acute burning/local pain, edema, erythema, and pruritus were symptoms already described, but its venom composition is unknown, as well as the participation of toxins for the symptom's development. Thus, herein, we show the biochemical composition and toxic effects of M. philippina venom. Colonies were collected and processed for histological analysis; alternatively, they were immersed into methanol containing 0.1% acetic acid for venom attainment, which was analyzed by mass spectrometry and submitted to edema and nociception evaluation in mice, hemolysis and antimicrobial assays in vitro. Before the molecule's extraction, it was possible to see the inoculation structures (hydrocladiums and hydrotheca) containing venom, which was released after the immersion of the animal in the solvents. The venom was composed mainly by low molecular mass compounds, able to cause significant reduction of the paw withdrawal latency from the hot plate test, 30 minutes after the injection. Moreover, significant edema was observed 10 and 30 minutes after the injection, indicating the activity of at least two inflammatory mediators. The venom caused no hemolytic activity but reduced the growth of A. baumannii and K. pneumoniae strains. This study is the first biochemical description of M. philippina venom, with molecules that cause fast inflammatory and painful effects, characteristic of the envenomation.

Spatial multi-criteria analysis to capture socio-economic factors in mangrove conservation

Mangrove forests are among the most productive ecosystems, located in tropical and subtropical coastal waters and river estuaries. Mangroves benefit both people and the environment by providing shelter for brackish-water organisms, such as fish and shrimp. They form a green-belt area that protects land from abrasion and tsunamis, along with goods and services for people, e.g., fruit, fish and charcoal. However, unmanaged use of mangrove ecosystems has resulted in a widespread decline in their function and conflicts between users. A paucity of research on mangrove management and spatial zoning is also contributing to the decline of these ecosystems. This study develops a prioritisation process with Spatial Multi-criteria Analysis (SMCA) for social-ecological mangrove management, based on a case study in Baros, Yogyakarta, Indonesia. We include social (participation and perception), demographic, economic (economic value of mangroves) and ecological criteria (water quality, mangrove density and diversity, phytoplankton diversity and density) criteria and spatial considerations informed by remote sensing imagery. We consider the three different conservation scenarios of habitat protection areas, sanctuary areas, and restricted areas to help configure management plan options. We demonstrate how SMCA can support managers and policymakers in mapping conservation areas based on complex and diverse social-ecological data. However, further discussion with stakeholders in Baros is required to validate the produced map for future use. The involvement of stakeholders and governing bodies from the beginning or within the SMCA analysis will always be crucial in community-based prioritisations.

Hammer it out: shifts in habitat are associated with changes in fin and body shape in the scalloped hammerhead (Sphyrna lewini)

Abstract Major shifts in habitat often occur during life history and can have significant impacts on the morphology and function of an animal; however, little is known about how such ecological changes influence the locomotor system of large aquatic vertebrates. Scalloped hammerheads (Sphyrna lewini) are large sharks found in warm temperate and tropical waters. Smaller scalloped hammerheads are generally found in near-shore habitats, but as they grow larger, individuals spend time in deep-water, pelagic habitats. We measured a number of morphological traits of scalloped hammerheads, ranging from 32 to 130 cm, to determine whether there are allometric changes in morphology in association with this shift in habitat. We found that head morphology, caudal fin area and lateral span scaled with negative allometry, whereas the lengths of their pectoral, dorsal and caudal fins, and their pectoral and caudal fin aspect ratios, scaled with positive allometry. Furthermore, the largest shark in our dataset exhibited an optimal body fineness ratio for locomotor efficiency. This suggests that the changes in ecology have profound influences on the functional morphology of scalloped hammerheads. We discuss how these drastic morphological changes relate to potential changes in scalloped hammerhead swimming function and performance.

Continuous electrocoagulation treatment of Borneo tropical brackish peat water from palm oil plantation region for domestic consumption in rural coastal areas

Sarawak located on Borneo Island has vast availability of tropical brackish peat water sources, especially at palm oil plantation regions in rural coastal areas. However, this water source is currently underutilized as source for water treatment plant in the state. As such, this study aims to investigate the feasibility of continuous electrocoagulation treatment to treat Borneo tropical brackish peat water at varied initial salinity levels for domestic consumption in rural coastal areas. Correspondingly, the main objectives of this study are (i) to conduct an experimental study analysis to treat tropical brackish peat water at varied initial salinity levels and residence time, (ii) to compare the treated water quality to the Malaysian National Water Quality Standard (NWQS), and (iii) to conduct energy operating cost analysis. Subsequent, this study has found that the treated water could meet the recommended levels in NWQS with maximum reduction efficiency at 94.09% of colour, 89.91% of total suspended solids, 63.19% of pH, 78.93% of electrical conductivity, 92.71% of chemical oxygen demand, 80% of salinity, and 86.04% of turbidity with optimal residence time of 5 min. From the energy operating cost analysis conducted, the optimal energy consumption cost only Ringgit Malaysia (RM) 0.12 or United States Dollars (USD) 0.03 per cubic metre of brackish peat water treated. Overall, the study has demonstrated that continuous electrocoagulation treatment is feasible to simultaneously reduce natural organic matters and salinity from Borneo tropical brackish peat water in which compliance to the NWQS at reasonable cost.

Water Mass Transports and Pathways in the North Brazil‐Equatorial Undercurrent Retroflection

AbstractThe equatorial retroflection of the North Brazil Current (NBC) into the Equatorial Undercurrent (EUC) and its posterior tropical recirculation is a major regulator for the returning limb of the Atlantic Meridional Overturning Circulation. Indeed, most surface and thermocline NBC waters retroflect at the equator all the way into the central and eastern Atlantic Ocean, before they recirculate back through the tropics to the western boundary. Here, we use cruise data in the western equatorial Atlantic during April 2010 and reanalysis time series for the equatorial and tropical waters in both hemispheres in order to explore the recirculation pathways and transport variability. During the 1998–2016 period, the annual‐mean EUC transports 15.1 ± 1.3 Sv at 32°W, with 2.8 ± 0.4 Sv from the North Atlantic and 11.4 ± 1.3 Sv from the South Atlantic. At 32°W most of the total EUC transport comes from the western boundary retroflection south of 3°N (7.2 ± 0.9 Sv), a substantial fraction retroflects north of 3°N (5.6 ± 0.4 Sv), and the remaining flow (2.3 Sv) joins through the interior basin. The South Atlantic subtropical waters feed the EUC at all thermocline depths while the North Atlantic and South Atlantic tropical waters do so at the surface and upper‐thermocline levels. The EUC transport at 32°W has a pronounced seasonality, with spring and fall maxima and a range of 8.8 Sv. The 18 yr of reanalysis data shows a weak yet significant correlation with an Atlantic Niño index, and also suggests an enhanced contribution from the South Atlantic tropical waters during 2008–2016 as compared with 1997–2007.

Water Mass Structure and Mixing Fractions in the Deepwater Region of the Gulf of Mexico

AbstractHere, we estimate water mass fractions in the deepwater region of the southern Gulf of Mexico from samples collected during June 2016. Past water mass characterizations have relied mainly on temperature, salinity, and dissolved oxygen concentrations, although the degree of mixing and the effects on the distribution of nutrients and other dissolved constituents remain uncertain. Based on nine water types defined in the eastern Caribbean Sea and North Atlantic and excluding surface waters, five dominant water masses with contributions between 50% and 93% in their cores were identified. North Atlantic Subtropical Underwater contributed 42% ± 9% between 49 and 105 m. Modal water with origins in the northern subtropical gyre (Eighteen Degree Water) were ubiquitous in the gulf, with average contributions of 62% ± 25% between 110 and 153 m and 51% ± 12% between 248 and 306 m, while the core of Tropical Atlantic Central Water (TACW; 70% ± 5%) dominated between 355 and 510 m. Water at the nitrate maximum consisted of TACW (48% ± 13%) and Antarctic Intermediate Water (AAIW; 32 ± 14%), with the local remineralization of organic matter adding ∼10% to the nitrate pool. Below ∼800 m, water transitioned from AAIW to a domain of two components of Labrador Seawater. Mesoscale eddies controlled the observed depth variability of the water masses from the surface down to ∼1,000 m. This study provides a quantitative approximation to evaluate the addition of nutrients to the different water masses by biogeochemical processes driven by an epipelagic ecosystem generally considered to be oligotrophic.

A Repetitive Parameterization and Optimization Strategy for the Calibration of Complex and Computationally Expensive Process‐Based Models With Application to a 3D Water Quality Model of a Tropical Reservoir

AbstractParameter calibration is critical for modeling, especially for current process‐based models that are complex with many chemical and biological processes and immeasurable model parameters. This analysis quantifies significant disadvantages of the traditional use of local or global sensitivity analysis (SA) for selecting calibration parameters of nonlinear, expensive models when there are a large number of constituents and parameters. We propose a new Repetitive parameterization and optimization (Rep‐OPT) strategy that uses multiple optimization steps; and between each optimization step, a modeler picks the parameters to be optimized in the next optimization step. The modeler picks the parameters in each iteration following a suggested set of steps that analyze which processes and parameters are related to the poorly fit constituents with the current parameter set. We successfully applied the Rep‐OPT strategy on a complex tropical water quality model with more than 91 parameters using real data. We demonstrate that expert knowledge with assistance of proposed postanalysis techniques (i.e., trade‐off analysis, component analysis, and mass‐balance analysis) can identify the right calibration parameters and obtain excellent model fit. In contrast, the traditional approach using SA with optimization (SA‐OPT) does not find the right calibration parameters for our data. The solution found by Rep‐OPT excellently improves manual solution by 32.7% in goodness‐of‐fit, and all calibrated constituents fit well to observations. The solution found by SA‐OPT using global SA improves manual solution by only 13.3%. Local sensitivity by SA‐OPT performs very poorly being 49.6% worse than manual solution.

Review on Remote Sensing Technologies for Seagrass Mapping in Tropical Region

Seagrass ecosystems can be mapped using RS because this technique is versatile and accurate. The availability of seagrass information is very important for the sustainable management of seagrass ecosystems. The use of RS technology to map seagrass has become the focus of many researches worldwide by using various types of platforms, sensors and various algorithms for satellite imagery processing. In literature, there have been many review papers related to seagrass, however, a comprehensive review on various aspects of seagrass is limited. The objective of this review paper was to fill the gap by highlighting the existing RS technology, seagrass biophysical property and image processing analysis. Review results indicated that RS technology is a powerful tool for accelerating seagrass mapping and for monitoring the condition of seagrass ecosystems at regional scale due to the availability of long-archived RS data and their free-access. In literature, the empirical approaches still dominated seagrass mapping methodology compared to the semi-analytic and analytic approaches. A clear conclusion from this review is that the development in sensor technology and data processing algorithm is still ongoing and has driven RS capabilities to map seagrass more rapidly, accurately and less expensive. Future research on seagrass mapping could be focused on a more automated classification by applying machine-learning to handle a large amount of data to improve accuracy and to discover robust methods for image pre-processing that is suitable for tropical shallow waters such as those in Indonesia.

Manajemen Pembenihan Ikan Kerapu Bebek (Chromileptes Altivelis) Untuk Menghasilkan Benih Yang Optimal

Humpback grouper Chromileptes altivelis is a marine fish that lives in tropical waters, especially in Indonesia. This fish has a high economic value and is the most expensive type of grouper in Indonesia. It can be used as ornamental fish or raised for consumption. Hatchery activities were started from brood rearing to produce productive broodstock, proper broodstock selection, multivitamin administration, and good environmental management. Humpback grouper was spawned en masse with a male to female ratio of 1:2. Fecundity of 1 female humpback grouper >300,000 eggs with a rematuration period of 20-30 days. Spawning using natural techniques accompanied by environmental manipulation, fish spawn for seven days during the dark moon. The number of eggs obtained was 560,000-2,000,000 eggs, with fertilization rate was 30-60%, and the hatching rate was 65-88%. The eggs that hatch into larvae were stocked with a density of 15-25 L-1. The larvae were transferred to a seed container at a size of 2-3 cm with a maintenance period of 40-45 days. Feeding at satiation using pellets measuring 1.1-2.0 mm with a protein content of 52-54% and 9-12% fat. Seeds were harvested at the age of 60 days when they reached a size of 5-6 cm, the survival rate was 3-5%.

A RUPELIAN CORAL REEF FISH ASSEMBLAGE FROM THE VENETIAN SOUTHERN ALPS (BERICI HILLS, NE ITALY)

Here we describe a new bony fish assemblage collected from a fossiliferous outcrop located in Perarolo, Berici Hills, Venetian southern Alps. The fossiliferous deposits pertain to the Rupelian (lower Oligocene) Castelgomberto Calcarenite and are indicative of a tropical marine shallow water setting associated with coral reefs. The assemblage is characterized by diminutive putative cryptobenthic fishes, including a single goby (family Gobiidae) and several cardinalfishes of the subfamily Pseudmiinae (family Apogonidae. Furthermore, a new apogonine of the extinct tribe †Eoapogonini, a new butteflyfish (family Chaetodontidae), and an indeterminate viviparous brotula belonging to the ophidiiform family Dinematichthyidae, are also present, and likely represented part of the epibenthic community. Some of the taxa described herein are among the first occurrences for their respective lineages in the fossil record. The Perarolo taxa document the first Oligocene coral reef fish assemblage known to date. Four taxa are described as new: †Arconiapogon deangelii gen. et sp. n., †Chaetodon (Blumchaetodon) wattsi subgen. et sp. n., †Oligopseudamia iancurtisi gen. et sp. n., and †Oniketia akihitoi gen. et sp. n.

Responses of digestive enzyme profiles to various scenarios of food availability in newly-hatched Stage I phyllosoma larvae of the tropical spiny lobster Panulirus ornatus

Stage I phyllosoma larvae of the spiny lobster Panulirus ornatus hatch in tropical oceanic waters with limited and variable food resources. To better understand how these larvae cope with food deprivation, this study examined specific (mU mg−1 protein) and total (mU larva−1) activities of major digestive enzymes (i.e., α-amylase, non-specific esterase, trypsin-like protease) during a series of ex situ experiments. Specifically, temporal changes in enzyme profiles were examined in three experiments simulating scenarios in which phyllosoma hatch and begin development in an environment where (1) prey is either continuously present or absent; (2) prey is initially present, but subsequently absent; (3) prey is initially absent, but subsequently present. Results indicated that the accessibility of suitable prey provides an overarching influence on digestive enzyme activities and substrate utilisation in Stage I phyllosoma of P. ornatus, with enzymatic responses to both intermittent prey availability and food deprivation being influenced by their nutritional history. In the absence of prey, larval digestive enzyme activities (mU larva−1) initially remained static from hatch but eventually declined with extended food deprivation. When prey became available, enzyme activities increased, with delayed access to prey having minimal impact on this enzymatic response. Furthermore, phyllosoma were able to adjust α-amylase and non-specific esterase activities (within 8 h) in response to the disappearance of prey, demonstrating adaptive changes to endure periods of food deprivation that were based on their nutritional history. The ability of phyllosoma to regulate enzyme activities from hatch is an important physiological strategy allowing them to survive in an environment characterised by highly variable zooplankton biomass and abundance, and explains why diets that differ greatly in nutrient composition have consistently been found effective for rearing phyllosoma in captivity.

True seals achieved global distribution by breaking Bergmann's rule.

True seals (phocids) have achieved a global distribution by crossing the equator multiple times in their evolutionary history. This is remarkable, as warm tropical waters are regarded as a barrier to marine mammal dispersal and—following Bergmann's rule—may have limited crossings to small‐bodied species only. Here, we show that ancestral phocids were medium sized and did not obviously follow Bergmann's rule. Instead, they ranged across a broad spectrum of environmental temperatures, without undergoing shifts in temperature‐ or size‐related evolutionary rates following dispersals across the equator. We conclude that the tropics have not constrained phocid biogeography.

Stable oxygen isotopes in planktonic foraminifera from surface sediments in the California Current system

Stable oxygen isotopes of Globigerinoides ruber s.l. and Globigerina bulloides have been widely used to infer the variability of the water column hydrographic structure over various time scales. However, the reliability of this geochemical tool requires a regional analysis since the inferred calcification depth and temperature of planktonic foraminifera depend on local environmental conditions. In the present study, δ18O values of G. ruber s.l and G. bulloides collected from 21 surface sediment samples were used to infer their calcification depth in the southwestern margin of the Baja California peninsula. The δ18O values of G. ruber s.l. represented oceanographic conditions from warm tropical water masses (summer-autumn), while G. bulloides represented upwelling conditions and cold-water masses (winter-spring). Estimated calcification depths ranged from 0 to 30 m for both species. The isotopic difference between them (1.2‰ in this study and 1.1‰ in the Guaymas basin sediment trap) suggests a sea temperature difference of ~5 °C, which is very similar to the difference inferred from the Mg/Ca ratio for both species 3 to 14 ka. This suggests that G. ruber s.l. and G. bulloides have calcified over the same depth interval but under contrasting seasonal oceanographic conditions i.e. upwelling (winter-spring) and stratification of the water column (summer-autumn).

Monsoon-driven biogeochemical dynamics in an equatorial shelf sea: Time-series observations in the Singapore Strait

Coastal tropical waters are experiencing rapid increases in anthropogenic pressures, yet coastal biogeochemical dynamics in the tropics are poorly studied. We present a multi-year biogeochemical time series from the Singapore Strait in Southeast Asia's Sunda Shelf Sea. Despite being highly urbanised and a major shipping port, the strait harbours numerous biologically diverse habitats and is a valuable system for understanding how tropical marine ecosystems respond to anthropogenic pressures. We observed strong seasonality driven by the semi-annual reversal of ocean currents: dissolved inorganic nitrogen (DIN) and phosphorus varied from ≤0.05 μmol l−1 during the intermonsoons to ≥4 μmol l−1 and ≥0.25 μmol l−1, respectively, during the southwest monsoon. Si(OH)4 exceeded DIN year-round. Based on nutrient concentrations, their relationships to salinity and coloured dissolved organic matter, and the isotopic composition of NOx−, we infer that terrestrial input from peatlands is the main nutrient source. This input delivered dissolved organic carbon (DOC) and nitrogen, but was notably depleted in dissolved organic phosphorus. In contrast, particulate organic matter showed little seasonality, and the δ13C of particulate organic carbon (−21.0 ± 1.5‰) is consistent with a primarily autochthonous origin. The seasonal pattern of the diel changes in dissolved O2 suggests that light availability controls primary productivity more than nutrient concentrations. However, diel changes in pH were greater during the southwest monsoon, when remineralisation of terrestrial DOC lowers the seawater buffer capacity. We conclude that terrestrial input results in mesotrophic conditions, and that the strait might undergo further eutrophication if nutrient inputs increase during seasons when light availability is high. Moreover, the remineralisation of terrestrial DOC within the Sunda Shelf Sea may enhance future ocean acidification.

Sea Surface Height Changes due to the Tropical Cyclone-Induced Water Mixing in the Yellow Sea, Korea

Sea surface height changes due to the tropical cyclone (TC)-induced water mixing in the Yellow Sea, Korea, were investigated using temperature and salinity profile data obtained by two Argo floats during the summer and fall of 2018 and 2020. Strong winds and low pressure, which are important characteristics of TCs, caused horizontal and vertical sea surface water movement and induced water mixing. This caused an increase in mixed layer depth, a decrease in water density, and an increase in specific volume. Specific volume changes related to the water steric effect were directly linked to sea surface height changes. During the TC Soulik (1819) period, the thermocline deepened by more than 10 m, and the steric sea level was increased by more than 3 cm. Other TC cases, such as Jebi (1821), Trami (1824), and Kong-Rey (1825), showed sea level increases of 1–2 cm. In 2020, 3 TCs–Bavi (2008), Maysak (2009), and Haishen (2010)—showed minor sea level increases (about 0.5–1 cm) because of weak mixing due to their high moving speeds or weak impacts. As a post-TC impact, the water mixing could cause a rise in sea levels due to the steric effect of seawater.

Wood Nutrient-Water-Density Linkages Are Influenced by Both Species and Environment.

Tropical trees store a large amount of nutrients in their woody tissues, thus triggering the question of what the functional association of these elements with other wood traits is. Given the osmotic activity of mineral elements such as potassium, sodium, and calcium, these elements should be strong candidates in mediating the water storing capacity in tropical trees. We investigated the role of wood nutrients in facilitating wood water storage in trees by using branch samples from 48 tropical tree species in South America and examined their associations with wood density (ρ). Wood density varied from 316 kg/m3 in Peru plots, where the soil nutrient status is relatively higher, to 908 kg/m3 in Brazil plots, where the nutrient availability is lower. Phosphorus content in wood varied significantly between plots with lowest values found in French Guiana (1.2 mol/m3) and plots with highest values found in Peru (43.6 mol/m3). Conversely, potassium in woody tissues showed a significant cross-species variation with Minquartia guianensis in Brazil showing the lowest values (8.8 mol/m3) and with Neea divaricata in Peru having the highest values (114 mol/m3). We found that lower wood density trees store more water in their woody tissues with cations, especially potassium, having a positive association with water storage. Specific relationships between wood cation concentrations and stem water storage potential nevertheless depend on both species’ identity and growing location. Tropical trees with increased water storage capacity show lower wood density and have an increased reliance on cations to regulate this reservoir. Our study highlights that cations play a more important role in tropical tree water relations than has previously been thought, with potassium being particularly important.

Research on fish identification in tropical waters under unconstrained environment based on transfer learning

Seafloor unconstrained environment video is shot in uncontrolled open sea area. There are multiple backgrounds, complex illumination and weather changes, and rapid growth of algae and attached lenses, which affect the stability of video shooting quality, resulting in difficulty in image recognition. At present, there is still no algorithm that is superior to other methods generally, and it is necessary to build a model combined with specific scenes and applications. In this paper, a fish identification method in tropical waters based on transfer learning under unconstrained environment is proposed. Firstly, the image is pre-processed by affine transformation to realize data enhancement. Furthermore, RestNet50 deep convolutional neural network is constructed based on transfer learning to compare the effect of fish recognition before and after transfer learning. The results show that, the accuracy and loss indicators are better than those of non-transfer learning when the trained model of imagenet is introduced as the initial weight of the network. When the model is trained to 150 epochs, the indicators begin to converge, which can better complete the fish identification task in tropical waters under unconstrained environment.

Hot water treatment before high relative humidity storage controlled cucumber shriveling and rot by Fusarium verticillioides

ISHS V International Conference on Postharvest and Quality Management of Horticultural Products of Interest for Tropical Regions Hot water treatment before high relative humidity storage controlled cucumber shriveling and rot by Fusarium verticillioides

Study on Total Protein and Amino Acid Profile of Milkfish (Chanos chanos) Meat and Its Product from Sidoarjo, East Java

Milkfish is one of the most cultivated fish species in Indonesia because these fish have a high tolerance to the various environmental conditions of tropical waters and are resistant to many pests and diseases. This preliminary research was conducted to analyze the amino acid composition contained in milkfish meat and its product. 20 fresh milkfish were obtained from ponds in Sidoarjo, East Java, in September 2020. Amino acid composition and protein content were analyzed. Based on its protein content, milkfish has been classified as a source of high protein. The amino acid profile of milkfish consists of approximately 17 types of amino acids. Glutamic acid, the amino acid present in the highest concentration, makes milkfish very popular.