Tank Size Guide

Tank Size Guide: Choosing the Right Aquarium

Picking the right tank size is one of the most important decisions in fishkeeping. It affects everything — your fish choices, maintenance schedule, water stability, and long-term success. Contrary to what many beginners assume, bigger is often easier. This guide will help you decide which tank size is best for your goals, budget, and space.

📏 Common Freshwater Tank Sizes

Tank Size Dimensions (L x W x H) Best For
5 Gallon 16" x 8" x 10" Bettas, shrimp, nano species
10 Gallon 20" x 10" x 12" Small community setups
20 Gallon Long 30" x 12" x 12" Guppies, tetras, dwarf cichlids
29 Gallon 30" x 12" x 18" Heavier community tanks, gouramis
40 Gallon Breeder 36" x 18" x 16" Cichlids, large planted tanks
55 Gallon 48" x 13" x 20" Large community setups

🔑 Factors to Consider When Choosing a Size

  • Experience Level: Beginners are better off with 20+ gallons due to easier water stability
  • Available Space: Measure the area and make sure the stand can support the weight
  • Budget: Smaller tanks are cheaper to start, but larger tanks are often more cost-efficient long term
  • Type of Fish: Some species require lots of room to swim or form schools
  • Maintenance: Small tanks need more frequent water changes; bigger tanks are more forgiving

🐟 Stocking Tips by Tank Size

The general rule is 1 inch of adult fish per gallon — but this is VERY dependent on species, filtration, and decor.

  • 5–10 Gallon: Betta + snail, shrimp colony, or 5 micro rasboras
  • 20 Gallon: 8–10 tetras, 4 corys, 1 dwarf gourami
  • 29–40 Gallon: Larger schools, dwarf cichlids, livebearer trios
  • 55+ Gallon: Rainbowfish, angelfish, medium cichlid setups

🛠️ Our Recommendation

If you're just getting started, go with a 20-gallon long. It gives you more flexibility, more stocking options, and better stability — all without taking up a huge footprint.

Need help choosing the right size for your space and fish wish list? Contact us anytime — we’ll build you the perfect game plan.