Sebaran ikan asing yang masuk dan tersebar awalnya adalah untuk tujuan peningkatan produksi, atau mengendalikan gulma. Namun makin lama jenis ikan asing tersebut sudah hampir masuk ke seluruh perairan Indonesia termasuk daerah Kalimantan Utara khusunya Sungai Kayan. untuk mengetahui spesies ikan invasive serta menyediakan data dasar untuk untuk berkelanjutan pengelolaan sumber daya ikan air tawar. Penelitian dilakukan dengan metode deskriptif pengukuran morfometrik meristik. Objek utamanya adalah ikan tembaring (Lutjanus Sp) air tawar dan air payau. Hasil penelitian menunjukkan ukurang panjang total 32 cm, panjang standar 24,5 cm, panjang ekor 7,8 cm panjang kepala 10,4 cm. Karakter meristic menunjukkan sirip dorsal, sirip pectoral, sirip pelvic, sirip anal, dan bentuk mulut terminal. Ikan tembaring muara Panjang total 30 cm, Panjang standar 23,2 cm Panjang ekor 2,2 cm , dan panjang kepala 10,4 cm bentuk mulut sub terminal, habitatnya hidup di sepanjang muara suangai air payau. Rasio perbandingan kedua spesies, analisa rasio ukuran diketahui pada nilai perbadingan ukuran karakter morfometrik tidak terdapat perbedaan, hanya pada rasio karakter ukuran TL (total length) dan ED (Eye Diameter). ikan tembaring air tawar atau di kenal dengan sebutan Lutjanus sp belum termasuk dalam kategori ikan invasive.
Kata Kunci: Sungai Kayan, Mofometrik–Merestrik, Identifikasi

The distribution of invasive fish that entered and spread was originally intended for production increase, or weeds controlling. However, over time these invasive fish species almost enter to all Indonesian waters, including the North Kalimantan especially the Kayan River. To identify invasive fish species and provide basic data for sustainable management of freshwater fish resources. The research was conducted by using a descriptive method of meristic morphometric measurements. The main objects of this research are freshwater and brackish water tembaring fish (Lutjanus Sp). The results showed that the total length was 32 cm, standard length 24.5 cm, tail length 7.8 cm, and head length 10.4. Meristic characters showed dorsal fin, pectoral fin, pelvic fin, anal fin, and terminal mouth shape. Estuary tembaring fish have total length 30 cm, standard length 23.2 cm, tail length 2.2 cm, and head length 10.4 cm with sub-terminal mouth shape, its habitat lives along the mouth of a brackrish water river. The comparison ratio of the two species, there is no difference of the ratio analysis in the comparison value of morphometric character sizes, the difference only in the ratio of TL (Total Length) and ED (Eye Diameter) size characters. Freshwater tembaring fish or known as Lutjanus Sp is not yet included in the invasive Keywords: Kayan River; Mophometric-Merestrike; Identification