| Odessa barb Barbus sp. Odessa |  |
| Oligancistrus sp. Polka Dot Oligancistrus sp. L020 |  |
| One-spot catfish Synodontis notatus |  |
| Ornate bichir Polypterus ornatipinnis |  |
| Ornate tetra, False rosy tetra, Bentos tetra, White-tipped tetra Hyphessobrycon bentosi |  |
| Oscar, Velvet cichlid Astronotus ocellatus |  |
| Oto, Midget suckermouth catfish, Dwarf sucker catfish Otocinclus affinis |  |
| Oligancistrus sp. L020 Oligancistrus sp. Polka Dot | |
| Oryzias latipes Rice fish | |
| Otocinclus affinis Oto, Dwarf sucker catfish, Midget suckermouth catfish | |
Low light plants Java moss, Java fern, and several of the Anubias species all do fine in low-light conditions. That is not to say that they do not thrive with stronger lighting, but in an aquarium with a lot of floating plants, or one with timid fish that prefer a dimmer tank, these plants are very useful indeed. All are epiphytes; that is to say they need not be planted, and can be attached to stones, bogwood or just left free floating