Dynamics of reproductive ecology of the fish Ompok bimaculatus (Siluriformes: Siluridae) in six tropical rivers of the Ganges basin, India

Abstract

The silurid butter catfish, Ompok bimaculatus (Bloch, 1794), is widely distributed in the plains and sub-mountain regions of India, but not enough is known about its reproductive potential is still insufficient. The present study evaluated the comparative reproductive potential (in terms of sex ratio, spawning season, body size at first go­nadal maturity, gonadosomatic index, fecundity, egg dimension, egg weight etc.) of fish (n=1223) from six tropical tributaries of the Ganges basin during January 2011-December 2013. The females had relatively greater weight and length. The body size at 50% first gonadal matu­rity (L50%) ranged between 228-262mm in females and 198-247mm in males. The population has high and low fecundities. The correlations between absolute fecundity and total length, as well as between body weight and gonad weight, were significant (p<0.05) and positive in all the population.

Photoperiod manipulation leads to successful voluntary captive spawning of butter catfish Ompok bimaculatus during the non‐spawning breeding season

“…The GSI of females and males in the 12L:12D and 15L:9D treatments reached 12.8%–13% and 2%–2.5%, respectively, in April. In April, the GSI of female and male O. bimaculatus ranged from 3.3% to 7% and from 0.24% to 0.5%, respectively (Malla & Banik, 2015; Praveen et al, 2017; Tumpa et al, 2020). In O. bimaculatus , the highest GSI observed in June to August denotes the spawning season, and it ranges from 7% to 9% in females and 2% to 2.5% in males (Mishra et al, 2013).…”

Growth Pattern, Sex Ratio and Distribution of Humpback Fish (Hemisilurus heterorhynchus, Bleeker 1854) in the Flooded River Basin, Kampar Kiri, Riau Province

“…Hasil tangkapan ikan dari bulan Oktober -Maret memberikan nilai nisbah kelamin 1.16:1, walaupun jumlah ikan jantan lebih banyak 6 ekor daripada betina, nisbah kelamin sudah mendekati pola seimbang dengan perbandingan 1:1, artinya ada keseimbangan populasi antara ikan janta dan betina. Hasil serupa juga ditemukan pada ikan Ompok bimaculatus yang diperoleh di enam sungai tropis Ganges basin, India (Praveen et al, 2017) dan 13 sungai berbeda yang ada di india yaitu (Sarkar et al, 2017) Keseimbangan nisbah kelamin ikan dapat menggambarkan keidealan suatu populasi ikan dalam mempertahankan kelestariannya, maka diharapkan perbandingan ikan jantan dan betina seimbang disetiap ikan yang sedang diteliti (Romimohtarto dan Juwana, 2001). Nisbah kelamin juga memiliki pengaruh terhadap proses pemijahan.…”

Perkembangan gonad, fekunditas dan diameter telur Hemisilurus heterorhynchus, Bleeker 1854 di sungai paparan banjir, Desa Mentulik, Kampar Kiri, Riau

“…Begitu juga dengan hubungan antara fekunditas dan berat gonad, pada Gambar 6 dapat dilihat bahwa nilai korelasi antara fekunditas dan berat gonad adalah r=0,97, hasil tersebut menunjukkan bahwa ada hubungan yang sangat kuat antara fekunditas dan berat gonad yang artinya semakin tinggi nilai fekunditas maka semakin tinggi pula berat gonad. Hal yang sama juga ditemukan pada ikan dari famili Siluridae lainnya seperti ikan Ompok bimaculatusyang ditemukan pada enam sungai di India, dimana fekunditas memiliki hubungan yang erat terhadap panjang tubuh, berat tubuh dan berat gonad (Praveen et al, 2017). Ompok pabdayang di Mymensingh, Bangladesh (Roy et al, 2021), Ompok bimaculatus di beberapa sungai di India (Sarkar et al, 2017).Ompok pabo di Tripua, India (Bhattacharya & Banik, 2015), Ompok bimaculatus di Tripura, India (Malla & Banik, 2015)…”