Biology of bonylip barb (Osteochilus vittatus Valenciennes, 1842) in Benanga Reservoir, East Kalimantan is not yet known. The purpose of this study was to analyze distribution of the length and body weight of fishes, sex ratio, gonad maturity level, length-body weight relationship, and condition factor. In total 278 fishes samples were collected during the five months, from January to May 2019 with a purposive sampling method at Benanga Reservoir, and gill net with  mesh size 0.5; 1; and 1.5  inches used. The results of this research showed that the total length of the fishes analyzed ranged from 72.21–196.57 mm and body weight ranged from 5.12–89.21 g. The sex ratio of male and female were 1:2.02. The male and female fishes were dominated by mature gonad. The length-body weight relationship models calculated for the total fishes sample was W=1x10-5L2.967 (r=0.988) for males, W=5x10-6L3.199 (r=0.989) for females and W=7x10-6L3.126 (r=0.987) for both sexes. Isometric growth patterns (b=3) were observed in males, meanwhile positive allometric growth patterns (b>3) were observed in females and both sexes. Calculation of the condition factor (K) resulted in 1.181±0.117 for males, 0.949±0.094 for females, and 1.026±0.150 for all specimens. The condition factors of bonylip barb from the Benanga Reservoir inside the range recommended as suitable for freshwater fish species in the tropical regions.

Silurid catfishes O. miostoma (Vaillant, 1902) is an endemic species in Mahakam Watershed East Kalimantan. Biology reproduction aspect of this species is not yet known. The purpose of this study was to determine the stages of gonad maturation characteristics, egg size, and spawning type. Fish sampling conducted monthly from November 2013 to Oc-tober 2014, using many gears at four locations in Mahakam Watershed, i.e: Semayang Lake, Belayan River, Siran River and Tering River. To determine the stages of gonad maturation in silurid catfishes were carried out by morphologic and histologic examination methods. Spawning fish type was determined based on the distribution of eggs diameter. The results of this research showed that there are five gonad maturation stages of males and females of silurid catfishes. Dis-tribution of eggs diameter in gonad maturity stages ranges from 0.54 – 1.30 mm with simultaneous spawning type.AbstrakIkan lais O. miostoma (Vaillant 1902) adalah spesies ikan endemik di Daerah Aliran Sungai (DAS) Mahakam Kaliman-tan Timur. Aspek biologi reproduksi ikan ini belum pernah diketahui. Penelitian ini bertujuan untuk menentukan karak-teristik tahap kematangan gonad, ukuran telur, dan tipe pemijahan. Pengambilan contoh ikan dilakukan setiap bulan, dari bulan November 2013 sampai Oktober 2014 menggunakan berbagai jenis alat tangkap pada empat lokasi penelitian di DAS Mahakam yang meliputi: Danau Semayang, Sungai Belayan, Sungai Siran, dan Sungai Tering. Penentuan ting-kat kematangan gonad ikan lais dilakukan dengan metode pemeriksaan morfologis dan histologis. Tipe pemijahan ikan lais ditentukan berdasarkan sebaran diameter telur. Hasil penelitian menunjukkan ada lima tahap kematangan gonad jantan dan betina ikan lais. Sebaran diameter telur pada tahap matang gonad berkisar dari 0,54 - 1,30 mm dengan tipe pemijahan serempak.

Bonylip barb (Osteochilus vittatus Valenciennes, 1842) that belongs to the Cyprinidae family is one of the native freshwater fishes in Indonesian waters. Currently, status of this species in Benanga Reservoir, East Kalimantan is in over-exploited. Fish resources management, therefore, is needed to maintained fish stock in the reservoir based on fish reproductive biology aspects. The purpose of this study was to analyze some aspects of the reproductive biology including sex-ratio, gonad maturity, length at first gonad maturity, spawning season, fecundity, and spawning patterns as basic information for its management. Fish collection was carried out monthly on the third week from January to May 2019 at three stations. The fish samples were captured by using experimental gill nets with mesh size of 1; 1.5; 2; and 3 inches. A total of 278 bonylip barb was caught, consist of 92 males and 186 females. Sex ratio of male and female in the gonad mature stage was 1: 2.4. The average length at first gonad maturity in male and female were 136.08 mm and 137.38 mm, respectively. Peak of spawning occurs during the rainy season in May, with more than 90% of fish in mature stage with GSI in male and female were 6.88%, 13.16% respectively. Total fecundity ranged from 7312-22923 eggs individual-1 and egg diameter ranged from 0.6-1.94 mm. According to distribution of egg diameter, bonylip barb was categoried as a total spawner. Some management strategies that can be carried out are using fishing gears with mesh size above 2 inches, limiting fishing activities in the peak of the spawning season, prohibiting fishing gear using electric shocker and protection the reservoir from erosion.

Diversity, potentiality and conservation status of fish fauna in upper Mahakam’s tributaries of east Kalimantan is unknown. The purposes of this study were to analysis species diversity, determine potentiality and conservation status of fish fauna in upper Mahakam’s tributaries, east Kalimantan. Fish sampling with purposive method was conducted in four tributaries, i.e Tepai River, Pahangai River, Danum Parai River, and Meraseh River for one month. Fishes were collected by several gears type. The results of this research showed that the total number of fish caught was 820 individuals; consist of 26 species, 7 families, and 4 orders. The Cyprinidae was the most dominant family found in all tributaries. The Shannon-Wiener diversity index in four tributaries were varied and ranging from 1.749-2.087. The highest fish diversity was recorded at Maraseh River followed by Pahangai River, Danum Parai River, and Tepai River. The low fish diversity was discovered at Tepai River may be due to differences in substrate type, water velocity, and water depth as compared to the Maraseh River, Pahangai River, Danum Parai River. The fish species similarity coefficient between four tributaries ranged from 0.606-0.842 and the highest dissimilarity was found between Tepai River and Danum Parai River. Almost all fishes categorized as edible fish for local consumption. Syncrossus hymenophysa and Gastromyzon lepidogaster have potential as ornamental fish. Regarding IUCN red list status, six fish species were grouped into least concern status, two species as data deficient, one species as near threatened, one species as endangered species and 16 other species were not on the list.