The short answer
Yes — you can mix tetras and guppies, provided you choose peaceful tetra species. Both are small, active and community-friendly, and pairing a shoal of each makes a lively tank. The key is temperament: avoid fin-nipping tetras that will shred a guppy’s long tail, and pick calm shoalers like neons, embers or rummynose instead.
Matching temperament and water
The main risk is fin-nipping. Guppies have long, flowing tails that some tetras — especially serpae and black skirt tetras — can’t resist nipping. Stick to peaceful species and both shoals will ignore each other. On water, there’s a mild mismatch: guppies prefer harder, more alkaline water while tetras like it softer. In practice most soft-water tetras adapt comfortably to the moderate middle ground guppies are usually kept in, so it’s rarely a dealbreaker. Keep each species in a proper shoal of 6 or more.
Good tetra-and-guppy combinations
- Guppies with neon tetras or ember tetras
- Guppies with rummynose tetras or glowlight tetras
- Avoid: serpae tetras and black skirt tetras (fin-nippers)
Keep 6+ of each species, and 2–3 female guppies per male to spread harassment. Give the tank plenty of planted cover so nervous tetras have somewhere to retreat and both shoals settle in quickly.
Before you stock
Cycle the tank first — see how to cycle an aquarium. Read the full guppy and neon tetra care guides, plan the wider mix with how to plan a community tank, and check guppy companions via good guppy tankmates.