HomeCompare fishRed rainbowfish vs Crescent betta Red rainbowfish vs Crescent betta: can they live together? Verdict: With cautionThe Red rainbowfish grows about twice as long as the Crescent betta; watch for bullying or predation.Both are comfortable at 24–25°C (75–77°F).A pH of 7.0 suits both.Minimum tank for the pair: 150 L (40 US gal)Side by sideRed rainbowfishCrescent bettaAdult size12 cm (4.7 in)6 cm (2.4 in)Minimum tank150 L (40 US gal)40 L (11 US gal)Temperature22–25°C (72–77°F)24–30°C (75–86°F)pH7.0–8.06.0–7.0Hardness9–19 dGH (161–339 ppm)5–19 dGH (89–339 ppm)TemperamentPeacefulPeacefulCommunity tankGoodGoodCare levelEasyEasyDietOmnivoreOmnivoreSpecies profilesRed rainbowfishGlossolepis incisusCrescent bettaBetta imbellis