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Abstract Betta dennisyongi and Betta rubra are ornamental fish native to Aceh waters, facing a decline in population due to overexploitation and environmental changes. Therefore, this research aimed to obtain information regarding the reproduction of B. dennisyongi and B. rubra. The study was conducted from January to December 2020, with B. dennisyongi and B. rubra samples collected from Nagan Raya Regency and Aceh Besar, respectively. Approximately 1,099 Betta fish samples were successfully collected, comprising 600 B. dennisyongi and 499 B. rubra. The results showed that sex ratio (male:female) analysis had 1:5 and 1:6 for B. dennisyongi and B. rubra, respectively, indicating a predominance of female. Further analysis showed that only 15% of female B. dennisyongi samples had mature gonads out of 505 and 3.7% of male among 95 B. dennisyongi. Female of B. dennisyongi showed first mature gonads at a size of 3.86 cm, while male had maturity at 3.99 cm. For B. rubra, only 11.1% of female and 26.9% of male samples showed mature gonads out of 432 and 67, respectively. Female of B. rubra first matured gonads at a size of 3.86 cm, while male had maturity at 3.90 cm. Reproductive analysis showed that both species were continuous spawners in the year, as indicated by mature gonads in each month of observation, with fluctuating percentages. The peak spawning period for B. dennisyongi occurred in October, while B. rubra was observed in January. Consequently, it was recommended not to catch these species during their spawning months to maintain the sustainability of these endangered species. Resumo Betta dennisyongi e Betta rubra são peixes ornamentais nativos das águas de Aceh, que enfrentam um declínio populacional devido à superexploração e mudanças ambientais. Portanto, esta pesquisa teve como objetivo obter informações sobre a reprodução dessas duas espécies. O estudo foi conduzido de janeiro a dezembro de 2020, com amostras de B. dennisyongi e B. rubra coletadas em Nagan Raya Regency e Aceh Besar, respectivamente. Aproximadamente 1.099 amostras de peixes Betta foram coletadas, compreendendo 600 B. dennisyongi e 499 B. rubra. Os resultados mostraram que a análise da proporção sexual (macho:fêmea) foi de 1:5 e 1:6 para B. dennisyongi e B. rubra, respectivamente, indicando uma predominância de fêmeas. Análises posteriores mostraram que apenas 15% das amostras de fêmeas de B. dennisyongi tinham gônadas maduras (de um total de 505), enquanto entre os 95 machos analisados, apenas 3,7% estavam sexualmente maduros. A fêmea de B. dennisyongi apresentou as primeiras gônadas maduras com um tamanho de 3,86 cm, enquanto o macho teve maturidade com 3,99 cm. Para B. rubra, apenas 11,1% das amostras de fêmeas e 26,9% dos machos apresentaram gônadas maduras de 432 e 67, respectivamente. A fêmea de B. rubra apresentou as primeiras gônadas maduras com um tamanho de 3,86 cm, enquanto o macho teve maturidade com 3,90 cm. A análise reprodutiva mostrou que ambas as espécies foram reprodutoras contínuas ao longo do ano, conforme indicado pelas gônadas maduras em cada mês de observação, com percentuais flutuantes. O pico do período de desova para B. dennisyongi ocorreu em outubro, enquanto o de B. rubra se deu em janeiro. Recomenda-se não capturar ambas as espécies durante os meses de desova, para manter a sustentabilidade dessas espécies ameaçadas.

BACKGROUND AND OBJECTIVES: Barbodes sellifer is a freshwater fish species that was recently discovered in the Aneuk Laot Lake ecosystem, Sabang City. Barbodes sellifer, an omnivore, plays a key role in the food web and adapts well to changes in food availability. This species serves a significant ecological function and may benefit local fisheries, yet there is a lack of information about its morphometric and genetic features. The objectives of study were to analyze the morphological traits and genetic diversity of Barbodes sellifer populations using a deoxyribonucleic acid barcoding approach. This technique is anticipated to disclose the population structure, genetic variation, and ecological adaptations of the species, supplying a scientific basis for sustainable aquatic management and conservation. METHODS: This study employed a morphometric and genetic approach comprising morphological analysis and genetic identification based on deoxyribonucleic acid barcoding. Barbodes sellifer specimens were collected from several sites within the lake using a purposive random sampling method. Morphological features were assessed via morphometric and meristic measurements, while genetic analysis utilized polymerase chain reaction with specific primers for cytochrome oxidase |. The resulting polymerase chain reaction products were then analyzed using bioinformatics software to identify genetic diversity and phylogenetic relationships among populations. FINDINGS: Morphological and morphometric analyses confirmed that one of the native fish species of Aneuk Laot Lake is Barbodes sellifer. For the first time, this newly documented Indonesian fish has been reported in a lake environment. The morphometric and truss measurements of Barbodes sellifer revealed the highest variation in total length (12.52 + 1.03 centimeters) and standard length (10.07 + 0.87 centimeters), while the lowest variation was in eye diameter (0.65 + 0.06 centimeters). Truss morphometric analysis showed the greatest distances in the anterior base of the dorsal fin to the junction of the head and ventral body (3.57 + 0.40 centimeters), and from the head-dorsal body junction to the anterior base of the ventral fin (2.99 + 0.37 centimeters). The shortest distances were from the anterior to the posterior base of the anal fin (0.88 + 0.11 centimeters) and between the dorsal and ventral caudal folds (1.21 + 0.13 centimeters). The findings indicate important facets of morphological variation in Barbodes sellifer, reinforcing studies on population structure and species differentiation. Genetic analysis further confirms this, showing the lake's native fish form a single clade with Barbodes sellifer, with 100 percent similarity based on phylogenetic analysis using the Barcode of Life Data System. CONCLUSION: This study presents the first report on the morphological and genetic characteristics of Barbodes sellifer within a lake ecosystem. Barbodes sellifer indicates ecological changes, highlighting the need for science-based, sustainable monitoring to maintain aquatic ecosystem balance. The results emphasize the critical role of morphometric and genetic techniques in grasping the population structure and genetic variation of native fish species, providing a scientific foundation for managing aquatic resources. The information obtained can be utilized in the development of conservation strategies and sustainable monitoring of Barbodes sellifer habitats in response to threats such as climate change, pollution, and overexploitation.

Mass coral bleaching causes population declines and mortality of coral reef species1 yet its impacts on behaviour are largely unknown. Here, we unite behavioural theory with community ecology to test whether bleaching-induced mass mortality of corals can cause consistent changes in the behaviour of coral-feeding fishes. We documented 5,259 encounters between individuals of 38 Chaetodon (butterflyfish) species on 17 reefs within the central Indo-Pacific, of which 3,828 were repeated on 10 reefs both before and after the global coral bleaching event in 2016. Aggression between butterflyfishes decreased by two-thirds following large-scale coral mortality, despite no significant change in fish abundance or community composition. Pairwise encounters were most likely to be aggressive between obligate corallivores and on reefs with high coral cover. After bleaching, the proportion of preferred Acropora corals in the diet decreased significantly (up to 85% fewer bites), with no increase in overall bite rate to compensate for the loss of these nutritionally rich corals. The observed reduced aggression at low resource levels due to nutritional deficit follows the predictions of the economic theory of aggressive behaviour2,3. Our results reveal synchronous changes in behaviour in response to coral mortality. Such changes could potentially disrupt territories4, leading to reorganization of ecological communities.

The Betta broodfish supply in Indonesia majorly comes from wild populations and fetches a higher price compared to hatchery cross-breeds, especially Betta rubra. This condition exerts pressure on the wild populations. Therefore, this study aims to examine the diversity, distribution, and conservation status of Betta fish species list in the study area. A total of 422 Betta fishes were collected from January 2019 to January 2021 from 19 of 59 sampling locations surveyed, consisting of four species, namely, Betta imbellis (TL: 14.09-31.98 mm; BW: 0.03-0.39 g), B. splendens (TL: 21.09-40.14 mm; BW: 0.05-0.70 g), B. rubra (TL: 11.35 to 47.80 mm; BW: 0.02-0.90 g), and B. dennisyongi (TL: 20.09-47.81 mm; BW: 0.07-0.91 g). There are four Betta species occurred in Aceh waters, namely B. dennisyongi, B. rubra, B. splendens, and B. imbellis. The results showed that B. dennisyongi was found at 8 sampling locations and had higher local distribution (13.56% LD) followed by B. rubra (8.47% LD), B. splendens (6.78% LD) and B. imbellis which had the lowest distribution and was only found in two locations (3.39% LD). Furthermore, field measurements (in situ) of water quality in the wild habitat showed temperature ranging from 23.7 to 31.9°C while pH ranged from 5.24 to 8.51. Based on the IUCN Redlist data, B. rubra is categorized as being critically endangered.

Mangrove ecosystem is one of tropical ecosystems that have important role for mitigating climate change through the ability of this vegetation to store carbon in AGB, BGB, and soil biomass. The study was conducted to estimate the carbon stock of Rhizophora mucronata as dominant mangrove vegetation in Gampong Pande, Kuta Raja District, Banda Aceh, Indonesia. This study carried out from April to July 2025. The aim of this research was to analyse the carbon storage in vegetation biomass, including tree, sapling, and seedling categories, as well as the soil organic carbon of R. mucronata mangrove ecosystems. The study employed a purposive sampling method across three stations representing different vegetation abundance such as sparse, moderate, and dense. Data collection was carried out non-destructively method using the quadrat transect, and biomass was estimated using specific allometric equations. Soil carbon was measured using the LOI method and bulk density analysis. The results showed that the highest biomass occurred at the dense vegetation station, with a total biomass of 78.5 tons/ha and carbon content of 36.895 tons/ha. Conversely, the highest soil carbon stock was recorded at the sparse vegetation station, reaching 69.3 tons/ha. These findings indicate that while vegetation biomass increases with higher density, soil organic carbon tends to accumulate more in areas with lower vegetation density. This study concludes that vegetation density affects the distribution of carbon stocks in both vegetation biomass and soil, and both parts must be considered together to obtain accurate carbon stock in mangrove ecosystems.

Hammerhead sharks are particularly vulnerable to fishing because of their slow growth rate and reproductive constraints. This type of sharks needs special attention due to its conservation status. This research was aimed to describe the relationships of the hammerhead sharks from West Aceh waters with the hammerhead sharks from other places. Samples of the shark were collected from Ujong Baroh Fish Port, West Aceh. The samples were analysed at the Laboratory of Department of Marine Science and Fisheries, Syiah Kuala University. The laboratory activity was started with extraction of DNA enhanced by Polymerase Chain Reaction method and visualized by an electrolytical. Analysis using BLAST showed that the first sample obtained 94%-95% cover query value and produced a 683 base pair length while the second sample obtained 98% per sample for a cover query value and produced a 658 base pair length. The average nucleotide values of the hammerhead shark were T=32.8, C=26.6, A=25.7 and G=14.9. The phylogenetic tree shows that the hammerhead sharks from the study area were more similar to the hammerhead sharks from Australia and Malaysia. Overall, based on the nucleotide composition, phylogenetic tree and genetic distance, the hammerhead sharks from the study area are unique compared to the populations from the other places.

The western-southern and northern coastal waters of Aceh are the potential fishing areas of spiny lobster, which faces the Indian Ocean and the Andaman Sea. Fishing gears that are widely used are lobster gill nets and hand-picking with compressors. In Indonesia, seven species of spiny lobsters are caught in these waters, including Panulirus homarus, P. penicillatus, P. versicolor, P. ornatus, P. polyphagus, P. longipes longipes , and P. longipes femoristiga . The habitat for spiny lobsters is spread from coral reefs, rock, sand, and muddy sand. Panulirus homarus is the most frequently caught species in these waters, followed by P. penicillatus and P. longipes. Panulirus homarus is mainly caught during the dry season (southwest wind) and high waves (May to July), where other lobster species experience a significant decrease in the catch. The stock of spiny lobster in Fisheries Management Area (FMA) 572 (including Aceh coastal waters) has been in an overfishing condition since 2008. Maximum sustainable yield (MSY) of spiny lobster in Aceh coastal waters part of Malacca Strait (FMA 571) is 188.60 tons.yr −1 with a total allowable catch (TAC) of 151.10 tons. yr −1 . Furthermore, the MSY for Aceh coastal waters part of Indian Ocean is 292.09 tons.yr −1 with a TAC of 233.92 tons.yr −1 . Spiny lobster fishing in Aceh coastal waters must ensure its use in the future, both ecologically, socially, and economically.

The objective of the present study was to explore the potential of avian hypophysis to induce the breeding of climbing perch. The pituitary glandof local chicken and duck and its combination was tested at the same dose of 0.5 ml/kg body weight (BW) of broodfish. Therefore, the tested treatments as follows; treatment A = 0.5 ml/kg BW of Ovaprim (control; Treatment B= 0.5 ml/kg BW of chicken pituitary extract; Treatment C= 0.5 ml/kg BW of duck pituitary extract; Treatment D= 0.25 ml/kg BW of chicken pituitary extract + 0.25 ml/kg BW of duck pituitary extract. The ANOVA test showed that treatment of avian pituitary extracts had a significant effect on the latency period, the total number of ovulatory eggs, fertility, hatchability, and survival of climbing perch larvae (P<0.05). The highest number of ovulated eggs was obtained in treatment B, this value was significantly different from treatments C and D. The highest fertility and survival were also obtained in the treatment B, but were not significantly different from the treatment C. Meanwhile, the highest hatchability was also obtained in treatment B and was significantly different from other treatments.

This research bridges a key phylogeographic gap for Nile tilapia ( Oreochromis niloticus ) in Asia by presenting pioneering DNA barcode data from Indonesia’s Singkil Peat Swamp ecosystem. We obtained partial cytochrome c oxidase subunit I (COI) one sequences from Singkil and complemented them with GenBank data from Bangladesh, China, India, Indonesia, Israel, Malaysia, Philippines, Qatar, Thailand, and Vietnam. Analysis of 67 sequences (639 bp) revealed high genetic diversity (haplotype diversity Hd = 0.933; nucleotide diversity π = 0.03232) with 22 identified haplotypes. Phylogenetic reconstruction identified three well-supported subclades: Subclade I (Indonesia, Vietnam, Malaysia, Philippines, Qatar, Thailand, Israel), Subclade II (Bangladesh, India), and Subclade III (exclusively China). This structure, corroborated by haplotype networks, reflects a complex invasion history driven by human aquaculture transfers rather than natural dispersal. The findings provide crucial genetic evidence for managing O. niloticus as distinct invasive lineages across Asia, with implications for biosecurity and conservation planning in biodiverse regions like Southeast Asia. These results provide crucial baseline data for monitoring spread and implementing targeted management strategies for this economically important yet invasive species.

Cherax quadricarinatus is an introduced species that is deliberately stocked in Lake Laut Tawar, Takengon, Indonesia. This study aims to analyze bio-population aspect of this species, including length frequency distribution, length-weight relationship, condition factors, and biology reproductive. A total of 361 individual was sampled bi-weekly from October to December 2021 in Lake Laut Tawar, Central Aceh, Indonesia. The carapace length of the crayfish ranged from 26.5 to 69.9 mm CL, with the length class mode being 41.69 mm CL. The growth pattern of freshwater crayfish is negative allometric ( b <3) as described as an equation W = 0.0002CL 29522 (R2 = 0.907). The sex ratio of C. quadricarinatus between male and female was in balance ratio (1:1) ( Chi-square test result). The length of maturity ( L 50 ) in male was 49.49 mm CL, while in female was 47.41 mm CL. The highest gonad somatic index (GSI) was in December at 1.02, while the lowest was in November at 0.79. Fecundity of female ranged from 267 to 970 eggs.