Asian Journal of Fisheries and Aquatic Research

Effects of Bait and Soaking Time of Umbrella Traps (Bubu Payung) on Catch in Rawa Pening Lake, Central Java, Indonesia

Laela Widia Wati — 2026-06-13

Rawa Pening Lake supports diverse freshwater fisheries where umbrella trap catches are strongly influenced by bait type and soaking duration, prompting this study to evaluate optimal bait–soaking combinations for improved fishing efficiency and sustainability. This study analyzed the effects of bait type (rucah fish, shrimp paste, golden apple snail) and soaking time (6, 12, 24 h) on umbrella trap catch in Lake Rawa Pening, Central Java, using a 3×3 factorial completely randomized design with seven replicates (63 units). Data included the number of individuals, weight, and species composition. A Generalized Linear Model (GLM) with a Poisson distribution was applied for count data (number of individuals), while a negative binomial GLM was used for weight due to extreme overdispersion. Total catch was 60 individuals (3,733 g), comprising marble goby (dominant: 90% of individuals, 95% of weight), freshwater crayfish, and silver rasbora. No significant interaction was found between bait type and soaking time for either number of individuals (p = 0.575) or weight (p = 0.391). Soaking time had a significant main effect, with 24 h producing 2.47 times as many individuals and 2.93 times as much weight as 12 h (6 h did not differ from 12 h). Bait type was not globally significant (p = 0.051 for individuals; p = 0.123 for weight). Pairwise comparisons showed that rucah fish and golden apple snail did not differ significantly (p > 0.05), but shrimp paste produced significantly fewer individuals than rucah fish (p = 0.048). Descriptively, golden apple snails with 24‑h soaking gave the highest mean catch (2.43 ± 0.79 individuals; 177.14 ± 90.32 g). Based on these findings, 24‑h soaking with rucah fish or golden apple snail is recommended; golden apple snail is a statistically equivalent and more economical alternative. Further studies with larger replicates and environmental controls are needed.

Identification of Octopus Species and Size Distribution in the Waters Surrounding Seriwe Village, East Lombok Regency, Indonesia

Dinda Kharisma Hafizah — 2026-06-13

Octopus is one of the main sources of livelihood for the community in Seriwe Village and an important fisheries commodity that supports Indonesia’s export activities. This study aimed to identify octopus species and analyze the size distribution of total length and mantle length of octopus in the waters of Seriwe Village, Alas Strait, in order to provide baseline data for sustainable fisheries management. This research employed an accidental sampling technique and was conducted in Seriwe Village, Jerowaru District, East Lombok Regency, West Nusa Tenggara Province, from April to August 2025. Primary data were obtained through direct measurements of 4,150 octopus individuals, including species identification, sex, total length, and mantle length. Species identification was carried out based on morphological characteristics, while size distribution analysis was performed using histograms in Microsoft Excel and compared with the length at first maturity (Lm). The results showed that all sampled individuals belonged to the species Octopus cyanea, consisting of 1,996 (48.1%) males and 2,154 (51.9%) females. The findings also indicated that female O. cyanea had a larger body size than males, with an average total length of 58.16 ± 13.72 cm for females and 57.25 ± 12.26 cm for males. The distribution patterns of both total length and mantle length were unimodal, with dominant size groups of 48–55 cm and 55–62 cm for total length, and 9–11 cm for mantle length. Monthly size distribution demonstrated population dynamics, where the population was dominated by medium-sized individuals from April to June, while from July to August larger individuals approaching the length at first maturity (Lm) began to appear, although in relatively low numbers. Most of the captured population was still below the size at gonadal maturity for both males and females, indicating that the population was dominated by juvenile to sub-adult phases. This condition may indicate fishing pressure on younger individuals due to continuous harvesting activities. If this pattern persists, it could increase the risk of growth overfishing and potentially threaten the long-term sustainability of O. cyanea populations in the waters of Seriwe Village.

Assessing the Impact of Invasive Nile Tilapia (Oreochromis niloticus Linnaeus, 1758) and African Catfish (Clarias gariepinus Burchell, 1822) on Commercial Carp Fish Production in Selected Water Bodies of Wanaparthy District, Telangana, India

Laxmappa Boini — 2026-06-15

The exotic fishes introduced into India for different purposes and some species has become invasive in inland waters. The spread of invasive fish is primarily driven by unauthorized aquaculture escaping into open waters. Nile tilapia, Oreochromis niloticus and African catfish, Clarias gariepinus once introduced in India have now established themselves in open water bodies as invasive species. The present study deals with the possible impacts of spread of African catfish and Nile tilapia into five selected water bodies i.e., Parameshwara tank, Apparala tank, Ooracheruvu tank, Ramasamudram tank and Gopaldinne reservoir in Wanaparthy district. The study was conducted from January 2023 to December 2025 to observe the impact of the above mentioned two invasive species on cultured commercial carp fish species. Data of Nile tilapia, African catfish, and other major commercial cultured carp fish catching were taken from the harvesting of the selected water bodies. The fish catch structure at the landing center was analyzed by direct observation of catches, graded as size-wise and species-wise with the help of local fishers. Results showed that commercial carp fish production was adversely affected by high density and abundance African catfish and Nile tilapia with established populations significantly and dominated over the cultured carp fish species during successive years. The present study recorded high Abundance Index (AI) 0.57 for tilapia, followed by 0.37 for carps and 0.06 for African catfish during 2023-2025. These results provide evidence of invasion success of the Nile tilapia and African catfish by adapting to the local environment for successful breeding. Results confirmed the correlation between the reduced catches of cultured carp fish production and the high abundance of Nile tilapia and African catfish. Thus, appropriate actions must be initiated for effective planning in terms of native commercial carp fish production. The data generated in the present study will help in realizing the serious threat from dominant species to native ones.

Fish Community Assemblages Response to Physico-Chemical Variables in River Riana, Kisii, Kenya

Jomo Boston Siriba — 2026-06-22

Rivers support freshwater biodiversity but are increasingly affected by changes in water quality arising from surrounding land-use activities. River Riana flows through agricultural, urban, industrial and forested areas, yet information on how its physico-chemical conditions relate to fish community structure remains limited. This study examined the influence of physico-chemical variables on fish diversity, distribution and abundance in River Riana, a tropical riverine ecosystem within the Lake Victoria Basin, Kenya. Five sampling stations representing different land-use types were selected according to accessibility and habitat characteristics. Triplicate water and fish samples were collected monthly from pools, riffles and runs from September 2022 to August 2023. Temperature, dissolved oxygen, conductivity, pH and total dissolved solids were measured in situ using a multi-parameter YSI meter. Fish were sampled using electrofishing and scoop nets and identified to species level using established taxonomic keys and FishBase. Two-way analysis of variance tested variation in physico-chemical variables, while the Kruskal-Wallis test assessed differences in fish abundance. Fish diversity was evaluated using Shannon-Wiener and Pielou’s evenness indices, and Pearson correlation analysis examined relationships between water quality variables and fish abundance. Physico-chemical variables varied across the study sites, with temperature ranging from 19.1–23.7°C, dissolved oxygen from 1.67–4.60 mg/L, pH from 3.11–7.78, conductivity from 60.3–341 µS/cm, and total dissolved solids from 43.2–224.69 mg/L. A total of 2,715 fish belonging to 5 families and 16 taxa were recorded. Fish abundance was highest at Station 5 (1,025) and lowest at Station 1 (74). Shannon-Wiener diversity ranged from 0.000 to 0.452, while Pielou’s evenness ranged from 0.000 to 0.176. The results indicate that physico-chemical conditions influence fish assemblages in River Riana and support the need for continued water quality monitoring and riparian management.