PERBANDINGAN JENIS KELAMIN DAN DIMORFISME SEKSUAL PADA PERTUMBUHAN IKAN GURAMI (Osphronemus goramy) SERTA IMPLIKASINYA TERHADAP STRATEGI SELEKSINYA

Abstract

Ikan gurami (Osphronemus goramy Lac.) pada ukuran dewasa memiliki bentuk morfometrik yang khas khususnya pada ikan jantan, sehingga dapat dibedakan antara ikan jantan dan betina. Ikan gurami jantan memiliki dahi menonjol dan bibir tebal. Penelitian ini bertujuan untuk mengevaluasi rasio kelamin dan perbedaan performa pertumbuhan antara jantan dan betina. Ikan uji yang digunakan adalah empat populasi ikan gurami yang berbeda yaitu: Kalimantan Selatan, Jambi, Majalengka, dan Tasikmalaya. Penelitian dilaksanakan di Balai Penelitian Pemuliaan Ikan (BPPI), Sukamandi pada bulan Juni 2014 sampai dengan bulan Juli 2015. Hewan uji yang digunakan adalah benih ikan gurami keturunan galur murni berasal dari Kalimantan Selatan, Jambi (strain Batanghari), Majalengka, dan Tasikmalaya. Perawatan telur, pemeliharaan benih, dan pembesaran menggunakan prosedur operasional standar BPPI tentang pemeliharaan ikan gurami. Pemeliharaan ikan gurami dilakukan selama 14 bulan. Hasil penelitian menunjukkan bahwa berdasarkan jenis kelaminnya jumlah ikan gurami betina (67,3%-80,7%) lebih banyak dibandingkan dengan jumlah jantannya (19,3%-32,7%). Setelah mencapai ukuran > 300 g terdapat perbedaan pertumbuhan antara ikan jantan dan betina (P<0,05) yakni jantan tumbuh lebih cepat dibandingkan betina pada semua populasi yakni berkisar antara 4,74%-5,67% untuk karakter panjang standar, dan 14,10%-16,52% untuk karakter bobot. Hal tersebut menunjukkan bahwa ikan gurami memiliki dimorfisme pertumbuhan. Oleh karena itu, ketika dilakukan seleksi berdasarkan pertumbuhan 10% terbaik didapatkan ikan jantan 55%-80% lebih banyak dibandingkan ikan betina (20%-45%).Adult size of giant gouramy (Osphronemus goramy, Lac.) has a distinctive shape of morphometric particularly in male fish, making it easy to distinguish between male and female fishes. Giant gouramy males have a prominent forehead and thick lips. This study aimed to determine sex ratios and differences in growth performance between males and females. This study used 4 progenies of giant gouramy seed from four different populations, namely: Kalimantan, Jambi, Majalengka, and Tasikmalaya, aged 14 months. Eggs incubations,seed maintenance and grow-out were conducted using Standard Operational Procedures of Research Institute for Fish Breeding (RIFB) about the rearing of giant gouramy. Seed rearing were carried out for 14 months. The results showed that, based upon the sex ratio, the number of female was more than the number of males, contituting females 67.3%–80.7% and males from 19.3% to 32.7% of populations. After reaching the size of > 300 g there were a significant difference in growth between males and females (P <0.05), in which males grew faster than females in all populations between 4.74%–5.67% for the standard length and 14.10%–16.52% for the weight characters. IThis result indicated that giant gouramy have growth dimorphism.Therefore, when the selection conducted based on the best growth of top 10%, it was found that the number of male composing 55%–80% was higher than the number of female which only accounted for 20%–45%.

Gender identification in farmed giant gourami (Osphronemus goramy): A methodology for better broodstock management

“…At this stage, some of the morphological criteria considered here for sexing are not fully developed yet. Although the first changes in the hump on the upper part of the head and in lower jaw thickening can be observed in fish as small as 0.3 kg (Sularto et al, 2017), they are not fully developed in individuals weighing less than 2.5 kg according to the West Java Gourami Center (BPPSIGN). The pigmentation on the outer part of the pectoral fin begins in individuals that weigh at least 0.2 kg and is considered as completely expressed in individuals of 0.5 kg (unpublished data).…”

“…In addition to these morphological observations, fish behavior is also examined by fish farmers. When males are held horizontally out of water, the caudal fin curves upwards and the muscles of the whole fish body contract and cause tremors (Tremor), whereas this particular behavior is not observed in females (Sularto et al, 2017).…”

“…To provide guidance for farmers, the Indonesian National Standard (SNI, 2000b) lists several morphological criteria for sexing giant gourami. At a body weight of about 300 g, gourami males show morphometric changes such as a hump on the forehead and thickening of the lips (Sularto et al, 2017). Nevertheless, these criteria are not well characterized and there are still errors in sexing.…”

“…For example, males appear to exhibit specific behavior, bending the body and contracting their muscles to produce tremors when held horizontally out of the water. This behavior has been suggested as a way to distinguish males and females in giant gourami (Sularto et al, 2017).…”

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“…The range of female Giant gourami's genital maturation is approximately 1 year, while gonad maturation and spawning are around 2-3 years. Giant gourami with 300 grams approximate weight starts to show several sexual behaviors and changes on shape and size which can be analyzed through morphometric study Sularto et al (2016), Giant gourami has asynchronous type of oocyte growth. There are various stages of oocyte growth in the ovary without the domination of an oocyte growth population (Lubzens et al, 2010).…”