HomeCompare fishFlag tetra vs Black phantom tetra Flag tetra vs Black phantom tetra: can they live together? Verdict: CompatibleBoth are comfortable at 22–28°C (72–82°F).A pH of 6.0–7.5 suits both.Minimum tank for the pair: 75 L (20 US gal)Side by sideFlag tetraBlack phantom tetraAdult size3.4 cm (1.3 in)4 cm (1.6 in)Minimum tank55 L (15 US gal)75 L (20 US gal)Temperature22–28°C (72–82°F)22–28°C (72–82°F)pH5.5–7.56.0–7.5Hardness5–15 dGH (89–268 ppm)2–18 dGH (36–321 ppm)TemperamentPeacefulPeacefulCommunity tankGoodExcellentCare levelModerateEasyDietOmnivoreOmnivoreSpecies profilesFlag tetraHyphessobrycon heterorhabdusBlack phantom tetraHyphessobrycon megalopterus