<em>The habitat ontogeny of arfak rainbowfish (Melanotaenia arfakensis) in Nimbai and Aimasi streams, Prafi river system were studied from June to December 2007.&nbsp; Sampling was carried out monthly in four different habitat types using hand net. Slow littoral and medium littoral are two habitat types which characterized by slowly water velocity, availability of submerged vegetation and warmer temperature, however the run and pool areas have higher water velocity and dissolve oxygen. The former habitats are essential for all developed stages, i.e. feeding, spawning and nursing of this species. On the other hand, the later habitat types particularly were only for young and adult fish, due to their swimming abilities as well as maximize of oxygen uptake. In order to maintain the population of this species, conservation is needed to all of their natural habitats for continuing their life cycles.</em>

Buyan and Tamblingan lakes were often mentioned as twin lake because of its adjacent location. These two lakes were separated by approximately one-kilometer forest. Studies which recorded the fish species in those lakes were very limited so that a study was needed regarding that conditions as the initial step of management. This study aims to reveal and analyze the ratio of native and alien fish species which were found in Buyan and Tamblingan lakes, Bali. The fish sampling was held three times in different months at Buyan and Tamblingan lakes during 2017-2018, using a purposive sampling method. There were six locations sampling fish on each lake. It used experimental gill net with mesh size 0.5; 1.0; 1.5; 2.0; 2.5; 3.0; 3.5; 4.0 inches and trap. Three of the nine species that found in Buyan and Tamblingan lakes were native fish species. The ratio of native and non-indigenous fish caught in Buyan lake was bigger than from Tamblingan lake. Based on the length size of the most captured fish, the native fish of Osteochilus vittatus in Buyan lake was longer than Tamblingan, while the non-indigenous one, Poecillia reticulata had the same length size on the two lakes.

Arfak rainbow fish, Melanotaenia arfakensis is an endemic fish on several river systems in the northeastern part of the Vogelkop peninsula. This study aims to describe the growth, age at first maturity, and sexual dimorphism of this endemic fish on the Nimbai Stream and the Aimasi Stream, the Prafi River system. The fish were caught using handnet, then were measured their standard length and individual weight. Data were analyzed to estimated growth patterns, von Bertalanffy's growth rate, age at first maturity and sexual dimorphism characteristics. The results showed that male growth patterns varied, with a tendency of the increase in body length faster than that of body weight (negative allometric patterns) with b values ranging from 2.886 to 3.132. On the other hand, the female individuals had positive allometric patterns (b values ranged from 3.062 to 3.378). The growth rate (K) of male body length was faster (0.165-0.174) than that of female individuals (0.159-0.163). Male individuals reached the first maturity condition earlier (at age of 1.83-2.18 years) than female individuals (at age of 2.49-2.64 years). Sexual characteristics between the sexes are related to body height starting to appear when fish are of a standard length of larger than 18.22 mm or when male fish begin to approach the time of the first sexual maturity. Understanding of growth, age, and the characteristics of the sexual dimorphism of endemic fish has an important meaning in monitoring population conditions and for conservation efforts in their natural habitat.

Pasar Sanggeng, pasar Wosi, pelabuhan, PLTD (Pembangkit Listrik Tenaga Disel), perhotelan dan pemukiman penduduk yang terletak di pesisir Teluk Doreri Kota Manokwari, menjadi salah satu pusat aktivitas yang melayani kebutuhan masyarakat. Akibat adanya aktivitas yang tinggi tersebut menyebabkan pembungan sampah-sampah organik dan anorganik tidak terawasi atau terkontrol dengan baik. Kondisi ini berlangsung secara terus menerus setiap hari sehingga dapat menyebabkan terjadi degradasi kualitas perairan. Tujuan Penelitian yaitu untuk mengetahui status kualitas perairan di Teluk Doreri Kabupaten Manokwari. Penelitian dilakukan dari bulan Agustus tahun 2016 bertempat di Laboratorium Kelautan, Ilmu Kelautan Unipa dan Laboratorium Prolink IPB Bogor. Lokasi pengambilan sampel air di sekitar perairan Sawaibu, Wosi, Andai, Sowi dan Perairan Maruni. Data parameter yang diambil melalui pengukuran langsung dan tidak langsung. Pengukuran secara langsung meliputi parameter salinitas, pH, suhu dan oksigen terlarut. Sedangkan pengukuran tidak langsung dengan cara mengambil sampel air. Pengambilan sampel air digunakan untuk penentuan parameter kekeruhan, nitrat, fosfat dan logam berat. Sampel air tersebut langsung dimasukan dalam botol polyetelin dan dikirim ke Prolink IPB Bogor untuk dianalisis. Pengukuran mengacu pada Standard Methods for the Examination of Water and Wastewater (APHA, 1998). Hasil penelitian dari lima lokasi di perairan Teluk Doreri berkisar antara 0,17 – 6,16 NTU untuk kekeruhan, 4,64 – 5,04 untuk pH, 5,1 -6 mg/L untuk oksigen terlarut, 30 – 33 ‰ untuk salinitas, 29, 8 – 30,6 oC untuk suhu air, 0,1 -0,8 mg/L untuk nitrat dan fosfat berkisar 0,08 – 0,16 mg/L. Hasil logam berat cadmium (Cd) menunjukan potensi toksik yang tinggi bagi biota perairan di Teluk Doreri. Parameter logam berat cadmium, nitrat dan fosfat sangat mengkuatirkan serta dapat menyebabkan gangguan terhadap lingkungan khususnya bagi biota perairan. Parameter – parameter tersebut telah melampaui baku mutu yang ditetapkan kementerian lingkungan hidup no 51 tahun 2004.WATER QUALITY IN THE DORERI BAY DISTRICT MANOKWARI. Traditional markets (Pasar Sanggeng and Wosi), port, PLTD (Power Plant), hotels and residential areas are located in the cost of Doreri bay in Manokwari district. Activities in those areas create organic and inorganic wastes that have been used the Doreri bay as a water dump. The waste has been dumped since long time ago and continue up to nowadays.  That cause water quality degradation of Doreri bay. The research objective was to determine the status of water quality in Doreri Bay, Manokwari Regency. The water quality study has been carried out in August 2016 in Marine laboratory of UNIPA and Prolink laboratory in IPB. Water samples collected from Sawaibu, Wosi, Andai, Sowi and Maruni beach.  Data were divided base on the data collection which is directly and indirectly collected. Water salinity, pH, temperature and dissolved oxygen are direct data collection. Turbidity, nitrate, phosphate and heavy metals are indirect data collection that has been analyzed in Prolink IPB. The water has been analyses by using Standard Method for Examination of Water and Wastewater (APHA, 1998). The results show that turbidity of five areas range from 0.17 to 6.16 NTU, pH range from 4.64 to 5.04, dissolved oxygen between 5.1 -6 mg/L, water salinity range from 30-33%, water temperature between 29, 8 - 30.6 oC, 0.1 -0.8 mg/L for nitrate and phosphate between 0.08 - 0.16 mg/L. Heavy metal (cadmium) showed high potential toxic risk on the biota of Doreri bay. Cadmium, nitrate, and phosphate are a heavy metal that categorized as concerned pollutant to the Dorery bay. Those heavy metal have been exceeded the water quality standard base on Ministry of environment number 51-2004.