Hikari Tropical Micro Pellets
$Slow-sinking micro pellets sized for nano and small community fish. The standard daily food for tetras, rasboras, and small barbs.
Walk into a pet store with no plan and you'll come home with a betta, two goldfish, an algae eater, and an angelfish — almost guaranteed to fight, die, or eat each other. A working community tank is the result of deliberate species selection: matched temperaments, matched water parameters, matched temperature, and matched bioload. Here's how to actually build one.
Think in three layers
A balanced community tank uses the whole water column. Pick one species (or one pair) from each layer:
- Top: hatchetfish, danios, guppies, top-water-feeding species
- Middle: tetras, rasboras, livebearers, angelfish (centerpiece), gourami
- Bottom: corydoras catfish, kuhli loaches, otocinclus, plecos (with caveats)
Layering reduces competition for territory and food and makes the tank look populated without overcrowding.
Schooling fish are non-negotiable
Most popular community fish — tetras, rasboras, danios, corydoras — are schooling species. Kept in groups of 6+ they're confident, active, and showy. Kept in pairs or singles they're stressed, hide constantly, and often refuse to eat. The single most common stocking mistake is buying "one tetra and one rasbora and one cory" — none of them are happy.
| Species | Min. school size | Tank min. | Notes |
|---|---|---|---|
| Neon tetra | 8 | 15 gal | Classic; needs soft acidic water |
| Cardinal tetra | 8 | 20 gal | Hardier than neons; brighter color |
| Ember tetra | 8 | 10 gal | Bright orange nano fish |
| Harlequin rasbora | 6 | 15 gal | Excellent for beginner communities |
| Chili rasbora | 10 | 10 gal | Tiny — perfect nano centerpiece |
| Cherry barb | 6 | 20 gal | Peaceful barb, despite the family reputation |
| Zebra danio | 6 | 20 gal | Active; cooler temperatures (65–75°F best) |
| Corydoras catfish | 6 | 20 gal | Pick one species; multiple cory species mix fine |
Sample 20-gallon community builds
The classic peaceful community
- 8 harlequin rasboras (middle)
- 6 panda corys (bottom)
- 1 betta or 1 honey gourami (centerpiece)
- 6 cherry shrimp + 3 nerite snails (cleanup)
The South American biotope
- 8 cardinal tetras (middle)
- 6 sterbai corys (bottom)
- 1 male apistogramma (centerpiece — peaceful dwarf cichlid)
- 3 nerite snails
The active dancer tank
- 6 zebra danios (top)
- 6 cherry barbs (middle)
- 6 bronze corys (bottom)
- 4 amano shrimp (cleanup)
Fluval Bug Bites Tropical Formula
$$Insect-protein-based pellets that fish actually go nuts for. Good rotation food alongside flakes; available in micro and small sizes.
Hikari Sinking Wafers
$Algae-and-vegetable wafers for corydoras, plecos, and other bottom dwellers. They won't compete for surface food; this gets to the bottom layer.
Fish to skip in a beginner community
- Common pleco. Grows to 18–24 inches and produces an enormous amount of waste. Get a bristlenose pleco instead — stays 4–5 inches.
- Goldfish. Coldwater, very high bioload, eat plants. Don't mix with tropical communities.
- Tiger barbs in mixed communities. Notorious fin-nippers. They're fine in a tiger-barb-only species tank but ruin a community.
- African cichlids in communities. Hard alkaline water requirements and territorial behavior. Beautiful, but commit to a species-only setup.
- Bala "sharks" and red-tail sharks. Bala sharks reach 14 inches and need a 6-foot tank. Red-tail sharks are territorial troublemakers.
- Chinese algae eaters. They grow large, stop eating algae, and start eating slime coats off other fish. Get otocinclus or amano shrimp instead.
Stocking calculator: the honest version
The classic "1 inch of fish per gallon" rule is wrong for almost everyone. It overstocks tanks with goldfish (which produce 5× the waste of a similar-sized tetra) and understocks tanks with neon tetras (which produce almost none). The honest approach:
- Match adult size, not store size. A 1-inch baby angelfish becomes a 6-inch adult. Plan for adults.
- Consider waste production. Tetras are clean. Goldfish, plecos, and cichlids are dirty. Adjust filter and stocking density accordingly.
- Leave swimming room. Fish need at least 6× their body length to swim comfortably.
- Allow for school sizes. 6 corydoras don't "count" as 6 fish — they swim as one social unit, but they still produce 6 fish worth of waste.
For the bigger picture of tank planning, see our complete setup guide. For the live-vs-fake plants decision, see our plant comparison.
FAQs
Can I keep different species of tetras together?
Generally yes — most peaceful tetras (neons, cardinals, embers, lemons, rummynose) get along well and may even mix schools. Avoid mixing serpae or buenos aires tetras with peaceful species; they're nippy.
Do I need a heater for a community tank?
If you're keeping tropical fish — yes. Nearly every popular community species (tetras, rasboras, livebearers, corys, gourami) is tropical and needs 76–80°F. Coldwater communities exist (white clouds, zebra danios, hillstream loaches) but are niche.
Can shrimp live with fish?
Cherry shrimp and amano shrimp coexist with peaceful community fish (rasboras, ember tetras, corys). Avoid betta, angelfish, gourami, larger tetras, and anything else that views shrimp as food. Shrimp need plenty of plant cover.
How many fish can I put in a 20-gallon tank?
A reasonable target: one centerpiece fish (gourami or apistogramma) + one schooling species of 6–8 + one bottom-dwelling group of 4–6 + invertebrates. Total: roughly 12–16 small fish. Less is more — overstocked tanks crash.
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