| Species | Adult size | Temperament | Min tank | Care | Accuracy |
|---|---|---|---|---|---|
| Senegal Bichir Polypterus senegalus | 25–50 cm | Semi aggressive | 540 L | Moderate | Verified |
| Serpae Tetra Megalamphodus eques | 3.5–4 cm | Semi aggressive | 90 L | Easy | Verified |
| Severum Hybrid / Unknown Heros Heros sp. hybrid | 15–25 cm | Semi aggressive | 300 L | Moderate | Verified |
| Shell Dweller Cichlid Neolamprologus multifasciatus | 3–5 cm | Semi aggressive | 60 L | Moderate | Verified |
| Shortfin Molly Poecilia sphenops | 5–10 cm | Peaceful | 100 L | Easy | Verified |
| Siamese Algae Eater Crossocheilus sp. | 12–16 cm | Peaceful | 200 L | Moderate | Verified |
| Siamese Fighting Fish Betta splendens | 5–7 cm | Semi aggressive | 45 L | Moderate | Verified |
| Silver Arowana Osteoglossum bicirrhosum | 75–90 cm | Aggressive | 2,000 L | Hard | Verified |
| Silver Dollar Metynnis hypsauchen | 18–20 cm | Peaceful | 650 L | Moderate | Verified |
| Silver Hatchetfish Gasteropelecus sternicla | 4–6.5 cm | Peaceful | 100 L | Moderate | Verified |
| Silver Tip Tetra Hasemania nana | 3.8–5 cm | Semi aggressive | 70 L | Easy | Verified |
| Similis Shell Dweller Neolamprologus similis | 3.5–5 cm | Semi aggressive | 60 L | Moderate | Verified |
| Sixbar Distichodus Distichodus sexfasciatus | 40–76 cm | Semi aggressive | 1,800 L | Hard | Verified |
| Sixray Corydoras Gastrodermus pauciradiatus | 2.5–4 cm | Peaceful | 60 L | Moderate | Verified |
| Skunk Corydoras Brochis arcuata | 5–7 cm | Peaceful | 120 L | Moderate | Verified |
| Skunk Loach Yasuhikotakia morleti | 8–10 cm | Aggressive | 240 L | Hard | Verified |
| Smudge Spot Corydoras Hoplisoma simile | 3.5–4.5 cm | Peaceful | 80 L | Easy | Verified |
| Snakeskin Barb Desmopuntius rhomboocellatus | 5–8.5 cm | Peaceful | 120 L | Moderate | Verified |
| Snakeskin Gourami Trichopodus pectoralis | 18–25 cm | Peaceful | 300 L | Easy | Verified |
| Spanner Barb Striuntius lateristriga | 15–19 cm | Semi aggressive | 300 L | Moderate | Verified |
| Sparkling Gourami Trichopsis pumila | 3–4 cm | Peaceful | 60 L | Easy | Verified |
| Splash Tetra Copella arnoldi | 4–5.5 cm | Peaceful | 80 L | Moderate | Verified |
| Spotted Blue-eye Pseudomugil gertrudae | 3–4 cm | Peaceful | 60 L | Moderate | Verified |
| Spotted Climbing Perch Ctenopoma maculatum | 10–15 cm | Semi aggressive | 180 L | Moderate | Not yet verified |
| Spotted Congo Puffer Tetraodon schoutedeni | 8–10 cm | Semi aggressive | 150 L | Hard | Verified |