Sea farm cages attract a range of wild fish species by providing shelter and food. The fish aggregation study was carried out around the open sea cages deployed at (9$^{\circ}$20$^{\prime}$03.95$^{\prime\prime}$N; 79$^{\circ}$19$^{\prime}$53.05$^{\prime\prime}$E) Olaikuda, Rameshwaram. A total of 2515 fish representing 51 species from 26 families and 9 orders were recorded by Underwater Visual Census (UVC) method from both sea-cage farm and control site. The genus Siganus was very common in both the cage and the control site and recorded in each sampling. The fish abundance distribution depicted a similar pattern to that of the cluster analysis when subjected to 2D NMDS ordinations and showed a distinct cluster pattern for the cage site. The Shannon Wiener diversity indices illustrated high abundance (224) and richness (7.33) at the cage site compared to the control site (common fishing ground). There was a significant temporal variation (F = 8.9, p  <  0.05) in the abundance of fish between the cage and the control site. In general, the congregation, density, and diversity of aggregated fish were much higher around sea cages than control site. This study reports the number of fish species in the vicinity of the cage system and the reasons for the congregation of fishes below the cage system was discussed in detail.