Fish & Aquarium Setup Guide: How to Set Up a Fish Tank the Right Way

Setting Up Your First Aquarium

Setting up an aquarium is one of the most rewarding things a pet owner can do — but it requires patience and planning. The most common mistake new fish keepers make is adding fish too soon. This guide walks you through every step of setting up a healthy, thriving aquarium from scratch.

Step 1: Choose the Right Tank Size

• Beginners: Start with at least a 20-gallon tank
• Bettas: Minimum 5 gallons; 10 gallons preferred
• Community fish: 20–55 gallons ideal
• Goldfish: Minimum 20 gallons for one, plus 10 per additional fish
• Avoid bowls and tanks under 5 gallons

Step 2: Filtration

• Hang-on-back (HOB): Easy, great for beginners — choose one rated 1.5–2x your tank size
• Canister filters: Best for 40+ gallon tanks
• Sponge filters: Gentle, perfect for shrimp, fry, or bettas

Step 3: Heating & Lighting

• Tropical fish need 75–80°F (24–27°C)
• Goldfish are coldwater and don't need a heater
• Use a full-spectrum LED for planted tanks; any LED works for fish-only
• Run lights 8–10 hours per day

Step 4: Substrate & Decorations

• Gravel: Classic, easy to clean
• Sand: Better for bottom-dwellers like corydoras
• Planted substrate: Nutrient-rich for live plant tanks
• Add caves, driftwood, and plants for hiding spots

Step 5: The Nitrogen Cycle (Most Important!)

Before adding fish, your tank must cycle — beneficial bacteria must colonize the filter to convert toxic ammonia into harmless nitrate. This takes 4–8 weeks. Skipping it is the #1 cause of new fish death.

• Test daily with a liquid test kit for ammonia, nitrite, and nitrate
• Cycle is complete when ammonia and nitrite both read 0 ppm
• Use a bacterial starter like Fritz Zyme or Seachem Stability to speed it up

Step 6: Condition the Water

• Add a dechlorinator like Seachem Prime — tap water chlorine is toxic to fish
• Let the tank run 24+ hours before testing

Step 7: Add Fish Slowly

• Add a few fish at a time over several weeks after the cycle is complete
• Acclimate by floating the bag 15–20 minutes, then slowly mixing tank water in
• Quarantine new fish 2–4 weeks before adding to the main tank

Equipment Checklist

• Tank with lid, filter, heater, thermometer, LED light
• Substrate, water conditioner, liquid test kit
• Gravel vacuum, fish net, decorations

Browse our fish and aquarium supplies collection for everything you need to set up a thriving tank.