Fish Diversity Indices Research Articles

Environmental DNA reveals spatial and temporal variation in fish communities before the 10-year fishing ban in the Poyang Lake Basin

Poyang Lake is the largest freshwater lake in China, and its unique ecosystem is an important biodiversity reservoir. Fish play an important role in the aquatic ecosystem of Poyang Lake. Accurate assessment of fish species diversity and community composition is essential for studies of fish ecology and conservation management. In this study, environmental DNA metabarcoding was used to analyze fish diversity and community structure in different habitats and seasons in the Poyang Lake Basin. A total of 52 fish species were identified, and limnicolous fish were the most abundant; most fish were omnivorous and small. The fish diversity index was highest in the spring and in the main lake area of Poyang Lake. Cluster analysis and non-metric multidimensional scaling analysis revealed significant differences in fish community structure among habitats. Water temperature and pH were the main environmental factors affecting fish community structure in the Poyang Lake Basin. Non-invasive environmental DNA monitoring methods could provide an important auxiliary method for monitoring fishery resources during the 10-year fishing ban period. This study provides basic information on the fish resources in the Poyang Lake Basin and has implications for fishery management and the development of ecological protection policies.

DIVERSITY OF FISH TYPES IN CIRAHAB SOURCE WATER AND WATER QUALITY FOR FISH ECOSYSTEMS IN CIRAHAB, CURUGGOONG VILLAGE PADARINCANG DISTRICT, SERANG-BANTEN

The research was conducted at water sources in Cirahab, Curuggoong village, Padarincang District, Serang-Banten Regency, research was conducted in January 2024, this research was conducted to determine the diversity of fish in the water source water ecosystem in Cirahab. The results obtained in the research There are 11 types of fish obtained during the research, including tilapia, goldfish, wader, betook, eel, nilem, chana, tawes, sili-sili, kampala (paitan) and catfish. The fish that dominate the waters of Cirahab are the wader fish which are often found there. Fishing is found in 3 places, namely places number 1, 2 and number 3. The category obtained in the fish diversity index is the "low" category because the value is -1.7255. The water parameters in Cirahab waters are ideal because they have a pH of 7, clarity of 90, water temperature of 23°C and an average depth of only 1 meter.

How economically and environmentally viable are multiple dams in the upper Cauvery Basin, India? A hydro-economic analysis using a landscape-based hydrological model

Abstract. The construction of dams threatens the health of watershed ecosystems. The purpose of this study is to show how multiple dams in a basin can impact hydrological flow regimes and subsequently aquatic ecosystems that depend on river flows. The approach assesses the ecosystem services (ESs), including the tradeoffs between economic and ecological services due to altered flow regimes. It uses a previously developed model that integrates a landscape-based hydrological model with a reservoir operations model on a basin scale. The approach is novel because not only does it offer the analysis of alterations in ecosystem services on a daily scale when pre-dam data are unavailable but also allows for dams to be synthetically placed anywhere in the river network and the corresponding alterations in flow regimes to be simulated in a flexible manner. As a proof of concept, we analyse the economic and ecological performances of different spatial configuration of existing reservoirs instead of synthetically placed reservoirs in the upper Cauvery River basin in India. Such a study is timely and conducted for the first time, especially in light of calls to assess the cascade of reservoirs in India and regions elsewhere where pre-dam data are unavailable. The hydrological impact of different configurations of reservoirs is quantified using indicators of hydrologic alteration (IHAs). Additionally, the production of two major ecosystem services that depend on the flow regime of the river, as indicated by irrigated agricultural production and the normalized fish diversity index (NFDI), is estimated, and a tradeoff curve, i.e. a production possibility frontier, for the two services is established. Through the lens of the indices chosen for the ecosystem services, the results show that smaller reservoirs on lower-order streams are better for the basin economy and the environment than larger reservoirs. Cultivating irrigated crops of higher value can maximize the value of stored water and, with lower storage, generate a better economic value than cultivating lower-value crops while reducing hydrological alterations. The proposed approach, especially when simulating synthetic spatial configurations of reservoirs, can help water and river basin managers to understand the provision of ecosystem services in hydrologically altered basins, optimize dam operations, or even prioritize dam removals with a goal of achieving a balanced provision of ecosystem services.

Reef fish community structure in the waters of small islands Central Bangka Regency

This study aimed to analyze the community structure of reef fish in the small island waters of Central Bangka. The research was conducted in March 2022 in the waters of Bebuar Island, Ketugar Island, Ketawai Island, and Gusung Asam Central Bangka Regency, Bangka Belitung Islands Province. The coral reef survey method uses purposive sampling and the coral reef fish visual census with data analysis of abundance, diversity index, uniformity, and dominance. In-site water quality measurements included six parameters: temperature, salinity, current, brightness, depth, and pH. The results showed that coral reef cover from 44.60 - 87.00% with the medium to very good category. The abundance of reef fish from 1 to 3 individuals/m2 was dominated by 18 species of the Pomacentridae family. The reef fish diversity index ranged from 2.47 to 2.90, including the medium category. The uniformity index value ranged from 0.79 - 0.94, including the high category, indicating that the species found were evenly distributed across all stations. The dominance index value ranges from 0.07 to 0.15, including low, where no species dominates significantly and the fish are evenly distributed. Temperature, brightness, pH, and salinity are factors that support the growth of coral and reef fish. A water current speed of 0.05 – 0.20 m/s is quite helpful in cleaning coral reefs from mud and can supply oxygen. Water conditions were categorized as good and fulfilled the seawater quality standards.

Diversity of fishery resources and catch efficiency of fishing gears in the Feni River (Bangladesh)

A thorough examination of fish diversity indices, gear efficiency, catch composition, and decline causes of fish diversity was carried out in the Feni River (Bangladesh). Monthly data collection took place from July to December 2023 at three stations of the river. A total of 8 fish species under 7 orders and 8 families were recorded. The order Perciformes was the most prevalent, representing 30% of the total. Approximately half of the identified species are classified as least concern, while the remaining 4 species are classified as Not Threatened (12.5%), Vulnerable (12.5%), Endangered (12.5%), and Critically Endangered (12.5%). The mean values of the Margalef’s richness (d), Pielou’s evenness (J), Simpson’s index (1-D), Shannon-Weaver diversity (H), and 0.973±0.002 were calculated as follows: 1.720±0.139, 0.699±0.112, and 0.248±0.034, respectively. Based on the Bray-Curtis similarity matrix, two groups were observed at a similarity of 58% within six months across the three sites. The chandi net and ghera net recorded the highest CPUE (kg gear-1day-1) at 5.93±0.966 and 0.53±0.041, respectively. The highest fish catch was recorded in July (2249 ± 668.71 kg), while the lowest was in October (1564 ± 465.05 kg). There was no significant difference (p>0.05) in the monthly fish catch. Fish biodiversity in the Feni River is declining day by day as a result of pollution, overfishing, the use of harmful gear, and a lack of optimal water and pollution. To improve and conserve fish species in the Feni River, it is strongly advised that appropriate fishery management techniques should be applied, that overfishing be closely monitored, and that fishermen be made more aware of their rights.

Fish diversity indices of Hail Haor, a subtropical wetland in the north‐east region of Bangladesh: Diversity influencing factors and recommendations

AbstractOne of the largest wetlands in Bangladesh's north‐east, Hail Haor supports a variety of aquatic habitats and has a diversified ecosystem. To ascertain the fish diversity indices of Hail Haor, this study was carried out month by month from December 2020 to June 2021. For this study, three sampling sites in the Moulvi Bazar district—Chiruadobi Beel, Gopla River and Balla Beel were chosen from which fish samples were collected. Twenty‐five different fish species were identified and 12,076 fish (individual numbers) were counted and categorized. The Shannon diversity index varied from 1.33 to 1.65. Hail Haor's species diversity index is moderate by the index standard. The Shannon evenness index (E) varied from .41 to .51. The Depressed Community is present in the Hail Haor species diversity index, as per the index standard. The Simpson dominance index fluctuated from .56 to .72. The species diversity index of Hail Haor contains moderate dominance, as per the index standard. With the help of local retailers, fishers, and other relevant stakeholders, the FGD identified factors that have an impact on the diversity index. The current study on diversity indices will be highly beneficial for formulating strategy and managing Hail Haor by strictly adhering to the recommendations.

Potential for aquatic cultural services in fresh water for fresh water- based ecotourism, Vawnikulam reservoir, in Mullaitivu, Sri Lanka

Freshwater-based tourism comprises both tourism and an ecotourism component. The current study evaluates the diversity of freshwater fish in water resources that may suffer from freshwater-based tourism (Ecotourism) within the zone and investigates conceivable opportunities for such ecotourism in Vawnikulam major reservoir in Mullaitive district, Sri Lanka. The Mullaitive district has distinctive topographical highlights that have a high potential for fresh water resources. These highlights include three major tanks, sixteen medium tanks, and more than 100 minor tanks. There are just 21,399 land-based freshwater bodies, 8% of the total land area, and no significant perennial rivers that can be used to irrigate crops. This study used a mix of primary (qualitative and quantitative) and secondary information sources. Multi-gillnet rods and hooks were chosen as the material for the particular harvest strategy, which was utilized to gather the sample. From January to December 2022, the Vawnikulam major reservoir within the Mullaitive district was considered. Fish diversity, relative abundance, and diversity indices were determined and applied to analyze the potential for ecotourism based on freshwater resources. During the study period, 28 species including 11 families were recorded. According to national conservation status (NCS) ,7 Endemic (E) species 14 Native species (NA), 6 Introduced species, and 1 species were Near threatened (NT) were identified. In order to disentangle the pathways of fresh water as aquatic cultural services and create fresh water-based ecotourism activities that can develop in Mullaitive district, Sri Lanka, this investigation distinguished the travellers within the considered area. It also analyses appropriate freshwater-based ecotourism activities.

Environmental DNA unveiling the fish community structure and diversity features in the Yangtze River basin

Fish, as top predators in aquatic ecosystems, play an important role in maintaining the structure and functioning of these ecosystems, making their diversity a topic of great interest. This study focused on the Yangtze River Basin to investigate the fish community structure and diversity using environmental DNA (eDNA) technology. The results showed that a total of 71616 fish operational taxonomic units (OTUs) and 90 fish belonging to 23 families were detected, with the Cyprinidae family being the dominant group, followed by the Cobitidae, Amblycipitidae, etc. Compared to historical traditional morphological fish surveys, the quantity of fish detected using eDNA was relatively low, but the overall distribution pattern of fish communities was generally consistent. The highest fish Shannon-Wiener diversity index in the Yangtze River Basin sites reaches 2.60 with an average value of 1.25. The fish diversity index was higher in the downstream compared to the middle and upstream regions, and there were significant differences among different sampling sites. Significant environmental factors influencing α-diversity included chlorophyll-a, chemical oxygen demand, dissolved oxygen, total nitrogen, and elevation. Non-metric multidimensional scaling (NMDS) analysis revealed significant differences in fish community composition between the upstream and middle/lower reaches of the Yangtze River, while the composition of fish communities in the middle and lower reaches was more similar. Redundancy analysis (RDA) indicated that total organic carbon (TOC) was positively correlated with fish community distribution in the upstream, while water temperature and NO3–N were negatively correlated with fish distribution in the upstream. NH3–N and CODMn were negatively correlated with fish distribution in the middle and downstream regions, indicating a relatively severe water pollution in these areas. Additionally, fish communities in the Yangtze River displayed a typical distance decay pattern.

Fish biodiversity and abundance of Thomas Dam, Danbatta Local Government Area of Kano State, Nigeria

Thomas Dam is one of the largest reservoirs in Kano, Nigeria and supports diverse fish species. Present study was carried out to assess the fish diversity status of the reservoir. Fish sampling was done monthly for a period of twelve months (January-December, 2022) using gill nets, cast nets, long lines, and different traps. A total of 1,318 fishes belonging to 6 families and 10 species were recorded during the study period. The results indicated Cichlidae as the dominant family represented by 4 species while Clariidae had representation with 2 species. Alestiidae, Mormyridae, Latidae, and Protopteridae were represented by 1 species each. Monthly fish diversity analyzed using nMDS (stress=0.06031) indicated influence of seasonality on the biodiversity of the Dam. The analysis of similarity (ANOSIM, P < 0.008, R = 0.47) show significant difference in fish assemblage structure between rainy season (June-September) and dry season (October-May). Also, Similarity percentage (SHRIMPER) analysis indicated 74.40% cumulative dissimilarity among the two Seasons contributed by five species; Protopterus annectens (29.85%), Brycinus nurse (15.47%), Oreochromis aureus (12.56%), Late niloticus (8.44%) and Sarotheroden galilaeus (8.08%). The fish diversity indices were calculated using PAST (version 3.22) software. Result of the diversity indices indicated Simpson’s diversity Index (1-D) and Shannon-Wiener index (H) values were highest during the months of rainy season of (1-D=0.85-0.89, H=2.06-2.24) indicating influence of the season on the fish diversity. The study concluded on the fact that changes of seasons have impact on the fish abundance and distribution of the Dam.

Fish diversity of the Bengawan Solo River estuary, East Java, Indonesia

Abstract. Hasan V, Andraini NE, Isroni W, Sari LA, Nafisyah AL, Dewi NN, Putri DNA, Prasasti TAB, Ramadhani AA, Daniel K, South J, Vieira LO, Ottoni FP, Maftuch, Faqih AR, Wirabuana PYAP, Tamam MB, Valen FS. 2023. Fish diversity of the Bengawan Solo River estuary, East Java, Indonesia. Biodiversitas 24: 2207-2216. Bengawan Solo River is the longest river in Java which flows from Mount Lawu and empties into the North Coast of Java. The watershed is a hot spot for fish species diversity, especially in the estuary area. The purpose of this study was to initiate an inventory of fish species, their abundance, and biodiversity assessment based on the Shannon diversity index (H'), evenness index (E), and dominance index (C) in the Bengawan Solo River estuary. The research was conducted from September to November 2022 at three stations with different ecological types and environmental conditions. Fish sampling was carried out using a gill net attached to a boat. In this study, 44 fish species from 22 families were identified. The highest abundance of fish was obtained from the Ariidae family, namely the Spotted sea catfish Arius maculatus (Thunberg, 1792) and Sagor catfish Hexanematichthys sagor (Hamilton, 1822). The fish diversity index obtained was 1.2-3.01, the uniformity index obtained was 0.7-0.92, and the dominance index obtained was 0.07-0.33. The H', E, and C at Station 2 have higher values ??than the other stations. The diversity expressed in H' values ??at the three research stations indicates that the mangrove in the Bengawan Solo River estuary area has a high diversity of fish species.

Diversity of freshwater fish at Sago Palm Wetlands, Nakhon Si Thammarat Province, Thailand

Abstract. Suriya C, Satian C, Visut B, Supadha K. 2022. Diversity of freshwater fish at Sago Palm Wetlands, Nakhon Si Thammarat Province, Thailand. Biodiversitas 23: 6335-6344. Studies on the diversity of freshwater fish at Sago Palm Wetlands, Nakhon Si Thammarat Province, Thailand, were conducted in the period from March 2020 to November 2020. Fish samples were collected, encompassing the hot-dry season (March to June) and the rainy season (September to November) at 4 sampling zones, with 5 stations for each zone. Fish were caught using a seine net of 1 cm mesh size, 1.5m in length, and 1m in width. All data were analyzed to find out the fish diversity indices. The multivariate method was used to determine cluster analysis. A total of 3634 fish specimens, representing 62 species belonging to 24 families, were recorded during the sampling period. Cyprinidae was the major family, with Trichopsis vittatus containing the highest index of relative importance (IRI). The species diversity index of fish was in the range of 0.66 to 2.67; the evenness index was in the range of 0.64 to 0.95, and the species richness index ranged from 0.36 to 6.86, indicating an intermediate-low uniformity, with a medium species number in the area. The cluster analysis of the Bray-Curtis similarity index shows A division of the fish community into 2 clusters in the hot-dry season and 3 clusters in the rainy season, having a similarity percentage ranging between 42% and 95%, respectively. Also documented were one introduced species and one endangered fish species during sampling. The findings suggest that Sago Palm Wetlands is still inhabited by numerous fish species and should be conserved to ensure its aquatic animal richness for the future. This data provides information about the fish habitat in the Sago Palm Wetlands and can be used to update the checklists of fish species in the Tapi River, the Pak Phanang River, and the Trang River Basins. It also can be useful for the planning of fishing activities and the provision of guidelines for future research and conservation purposes.

The Diversity of Fish in The Aek Sibundong District Dolok Sanggul Regency Humbang Hasundutan

The diversity of fishes in Aek Sibundong, Dolok Sanggul regency, Humbang Hasundutan district, was conducted from April to October2018. The aim of this research was to analyze variety of fishes and their physical-chemical factors related to fishesin Aek Sibundong. This research used purposive sampling method on four location based on human activities. The first location was stationed with no activities, the second location tofu waste disposal station, the third location was slaughter house station and last location was belonge to sand dredging station. Sampling used nets as trap for the fishes. Seven species of fishes had been found from the sites where classified into 3 order ( spesies from ordo Cypriniformes 4, Perciformes 1 and Siluriformes 2). The result showed that station 1 had the highest fish density was 0,59 ind/m2 belong to Tor tambroides and the highest fish diversity index at 1,318. The temperature, light intensity, light penetration, phosphate, and Biochemical Oxygen Demand (BOD5) had strongly correlated with fish diversity in the waters of the Aek Sibundong.

Diversity of Fish in Idanoi River and It’s Relationship to Physical Factors of Water Chemistry

A river is an area through which a body of water moves from a high place to a low place either through the surface or underground which has an average width equal to or more than 5 meters. One of the rivers in Indonesia is the Idanoi river, located in the North Sumatra region, Ononamolo 1 Lot village, Gunungsitoli Selatan sub-district, Nias. This river is inseparable from human activities which affects the condition of river waters as a habitat for aquatic biota. The purpose of this study was to analyze the diversity of fish species in the river Idanoi and to analyze the physical-chemical factors of waters which correlate with the diversity of fish species in the river Idanoi. This study uses the Random sampling method. The results of the research obtained from the four research stations found 1 class, 5 orders, 7 families and 7 species. The highest density value was found at station 1 with a value of 0.023 ind / m2, fish diversity index ranged from 1.072 - 1.829 and the fish uniformity index ranged from 0.92 to 0.98. DO, BOD5 values and oxygen saturation correlated very strongly with fish diversity in river Idanoi village Ononamolo 1 Lot.

Structure of Fish Community in The Alas River of Aceh Tenggara District

Research on the Community Structure of Fish on the Alas River in Babul Makmur sub-district Aceh Tenggara district was conducted from April to October 2018. The aim of this research was to analyze the structure of fish communities and to analyze physical-chemical factors related to fish community structures in the water of the Alas River in Babul Makmur sub-district Aceh Tenggara district. This research using "Purposive Sampling" method on the location based on human activities i.e the tributary of the Lawe Pakam (household waste disposal), the meeting of 2 rivers (sand dredging), the river parent (tourism), the mountain stream (free of activity). Sampling using nets. Seven species of fish obtained from the study sites were classified into 3 ordo (Cypriniformes, Perciformes, Siluriformes). The result showed that station 1 had the highest fish density at 0.3 ind / m2 for species Tor tambroides. Station 3 had the highest fish diversity index at 1.6213. Temperature, phosphate, light intensity, light penetration, dissolved oxygen and oxygen saturation had strongly correlated with fish diversity in the waters of the Alas River.

Ichthyofauna diversity in Pematang Matik Coastal Waters, Serdang Bedagai District, North Sumatra, Indonesia

Abstract. Wahyuningsih H, Sinaga SMS, Hartanto A. 2022. Ichthyofauna diversity in Pematang Matik Coastal Waters, Serdang Bedagai District, North Sumatra. Biodiversitas 23: 4992-5000. Pematang Matik Coastal waters are coastal areas that have a major role in the life of various fish species. Research on fish diversity in coastal waters is very important in order to gain a better understanding on the fish diversity in coastal areas such as North Sumatra, including Indonesia. The objective of this study was to initiate an inventory of fish species, their abundance and assessment of its biodiversity based on Shannon's diversity index (H'), and evenness index (E) in Pematang Matik coastal waters. The research was conducted from September to October 2021 at four stations with different human activities by the coastal community. Fish samples were taken using fishing nets that were installed for 12 hr with two replications. In this study, 21 species of fish from 19 families were identified. The highest abundance of fish was obtained from the Mugilidae family, namely Crenimugil crenilabis and Liza macrolepis. The fish diversity index obtained was 2.19-2.95, while the uniformity index obtained was 0.719-0.968. The values ??of H' and E at Station 4 (absent from any human interferences) have higher values ??than the other three stations. The diversity, as expressed in H' value in four research stations, indicates that the coastline has a high diversity of fish species.

Sumberdaya Ikan Asli dan Invasif di Sungai Mengkiang, Kabupaten Sanggau, Kalimantan Barat

Mengkiang River is a river located in Sanggau Regency. Information from local communities and fishermen Information related to the waters of the Mengkiang River, there are several types of fish that are protected, invasive and endemic.This study was conducted to determine the condition of native and invasive fish resources in the waters of the Mengkiang River. The information from this study is expected to be used to formulate control measures as input for the formulation of regulations and policies by the government. Sampling was carried out at 3 observation stations, namely the upstream, middle, and downstream parts of the river. The aim is to show the value of sommunity structures such as index of fish diversities, the similarities, dominances, native and aliens species. The number of fish species that have been identified as many as 8 species, there are 7 native fish, namely: Bilis (Anchoviclla commersoni), Lais (Cyptopterus micronema), Seluang (Rasbora Sp.), Tengadak (Barbonymus schwanenfeldi), Hampala (Hampala macroleptitoda), Tilan (Barbonymus schwanenfeldi), Baung (Mystus) and 1 type of invasive fish, namely Toman fish (Chana Pleurophthalma) Diversity Index Value (H') 1.85861622. The value of the Diversity Index in the waters of the Mengkiang River is included in the medium group, namely moderate distribution and moderate community stability. Stable community that is high similarities Index Value. The Dominance Index value of the Mengkiang River is included in the low criteria. The condition of the waters of the Mengkiang River is still in good and well-maintained condition.

Biodiversity in the Cipeles River, Sumedang Regency, West Java Province, Indonesia


 This study aims to determine the diversity of fish species and to analyze the condition of water quality in the Cipeles River, Summedang Regency, West Java Province, Indonesia. The research was conducted for one month. The research method used was census with purposive sampling technique. The sampling period is four times a week. Analysis of the data used in this study is the composition of fish species, relative abundance, diversity, and water quality with quantitative descriptive data analysis. The results showed that the fish caught were baung (Mystus cavasius), singaringan (Mystus singaringan), tilapia (Oreochromis niloticus), hampala (Hampala macrolepidota), paray (Rasbora aprotaenia), genggehek (Mystacoleucus marginatus), lalawak (Barbonymus balleroides), and and julung-julung (Dermogenys pusilla). The fish diversity index value 0,85 – 0,89 was categorized as low with the highest relative abundance of genggehek fish (Mystacoleucus marginatus) at stations I and III, and lalawak fish (Barbonymus balleroides) at station II. The native fish of the Cipeles River that was able to adapt from 2001 until now is M. marginatus.

Establishment of a fish sanctuary for conserving indigenous fishes in the largest freshwater swamp forest of Bangladesh: A community-based management approach

Fish sanctuary is considered as an important structural management tool for restoring fish biodiversity and enhancing fisheries production. Therefore, this study was conducted in the Ratargul Swamp Forest (RSF) of Bangladesh to evaluate the impact of a fish sanctuary on native fish biodiversity in and around the forest ecosystem. The investigation was carried out through focus group discussions, personal interviews, and direct catch assessments during fishing operations by the local fishers. After two years of study, 65 species of indigenous fishes were recorded for 46 genera under 23 families covering 9 orders, where Cypriniformes and Cypriniidae are the dominant order and family, respectively. After the establishment of the fish sanctuary, there was an increasing tendency of fish population was observed in the RSF and the adjacent Shari-Goyain and Kapna Rivers. In the RSF, fish diversity indices such as Simpson dominance index (D), Shannon-Wiener diversity index (H), Margalef richness index (d), and Pielou evenness index (J) varied from 0.12-0.09, 2.77–2.98, 6.15–6.14, and 0.66–0.71, respectively indicating species diversity enrichment in the final year compared to baseline assessment year which is supposed to be associated with the impact of fish sanctuary establishment. That assumption is further supported by remarkable increase in average fish catch (11.38%). Local fishers and people adjacent to RSF perceive that sanctuary became useful for protecting biodiversity, increasing fish production as well as improving their livelihood conditions.

Biodiversitas Ikan Kawasan Perairan Estuaria

This study aims to determine the biodiversity of fish caught in the estuary waters of Sungai Bilah. The method used is explorative with determining the point of observation using purposive sampling. Fish samples were caught using splint nets. The results showed that Ambassidae and Cyprinidae dominated the relative frequency at the family level. The composition of fish species caught with the highest number was Seluang fish (109 individuals) and Sepongkah fish (107 individuals). The fish diversity index at stations 1, 2, 3 was categorized as medium and the uniformity index value was high at station 1, while at stations 2 and 3, it was classified as moderate. The dominance index values at stations 1, 2, 3 indicate that no species dominates. In conclusion, fish biodiversity in the estuary waters of Sungai Bilah is still quite good.
 Keywords: Fish Biodiversity, Estuary, Sungai Bilah

Reef fish diversity in the Legon Bajak Port, Kemujan Island, Karimunjawa National Park

Karimunjawa National Park provides substantial reef fish resources, leading to higher market demand for reef fish production. This study aims to determine the diversity of reef fish, particularly in regions where fishing boats dock, specifically in Legon Bajak Port, Kemujan Island, Karimunjawa National Park, Jepara, Central Java. The findings of this investigation should enrich previous studies. The study was conducted on the right and left sides of the Legon Bajak Port. The visual count of belt transects was used to obtain data on reef fish. The study results obtained the number of reef fish at the Legon Bajak Port was 2769 individuals/500 m2 on the right and 1809 individuals/500 m2 on the left side, representing 40 species, 26 genera, and 13 families. Istigobius rigilius had the largest density of individuals, with 233 individuals/500 m2. The fish diversity index (H') value on the right side of the Legon Bajak Port was 3.24, which includes the high category, and on the left side was 2.89, which includes the medium category. The dominance index (D) was between 0.05 and 0.06 (low), while the uniformity index (E) was between 0.74 and 0.83 (unstable in a stable community).