30 Gallon Tank Overview
The 30 gallon aquarium measures 36" × 12" × 16" — sharing the same width and height as many 20 gallon variants but adding 6–12 inches of length. This 3-foot tank provides a noticeable step up in swimming room and stocking capacity over 20 gallons while remaining practical for most homes.
At about 348 lbs filled, a stand is strongly recommended but the tank is still manageable compared to the 55+ gallon range. The 30 gallon is particularly popular for single goldfish setups and angelfish pairs.
Best Fish for a 30 Gallon Tank
Common Goldfish
30 gallons is the minimum for a single common or comet goldfish (they need the length for swimming). These fish can reach 12+ inches and produce enormous waste — heavy filtration is essential. Add 10+ gallons per additional goldfish.
Angelfish Pair
A pair of angelfish with a school of medium-sized tetras (rummy nose, black skirt) and corydoras. The 16" height is adequate for angelfish development.
Large Community
10–12 tetras + 6 corydoras + 4–6 livebearers (platies or swordtails) + 1 bristlenose pleco + 1 dwarf gourami. A diverse, vibrant community.
Rainbowfish School
6–8 Boesemani or Praecox rainbowfish with a corydoras school. The 36" length gives these active swimmers room to show off.
Equipment
- Filter: AquaClear 50 (HOB) handles a standard community. For messy fish like goldfish, upgrade to AquaClear 70 or a canister filter (Fluval 207).
- Heater: 100–150W adjustable. 150W for rooms that get cool.
- Light: 36" fixture. Nicrew ClassicLED Plus or Fluval Plant 3.0 (36") for planted setups.
Frequently Asked Questions
30 gallon vs 29 gallon — what's the difference?
A 29 gallon is 30" × 12" × 18" (taller, shorter). A 30 gallon is 36" × 12" × 16" (longer, shorter). The 30 has 6 more inches of swimming length but 2" less height. For most fish, the extra length is more beneficial.
How many fish in a 30 gallon?
20–30 small fish or fewer larger species. The 3-foot length supports a diverse community with species occupying different zones.
Can I keep goldfish in a 30 gallon?
One common/comet goldfish — yes. One or two fancy goldfish — yes. Multiple common goldfish — no, need 40+ gallons.