Flag tetra vs Red phantom tetra: can they live together?

Verdict: Compatible

Both are comfortable at 22–25°C (72–77°F).
A pH of 5.5–7.5 suits both.
Minimum tank for the pair: 55 L (15 US gal)

Side by side

	Flag tetra	Red phantom tetra
Adult size	3.4 cm (1.3 in)	4 cm (1.6 in)
Minimum tank	55 L (15 US gal)	55 L (15 US gal)
Temperature	22–28°C (72–82°F)	22–25°C (72–77°F)
pH	5.5–7.5	5.5–7.5
Hardness	5–15 dGH (89–268 ppm)	4–20 dGH (71–357 ppm)
Temperament	Peaceful	Peaceful
Community tank	Good	Excellent
Care level	Moderate	Easy
Diet	Omnivore	Omnivore