Quick answers to the most common questions we get about aquariums and fishkeeping.
Getting Started
What’s the best fish for a beginner?
For most beginners, a hardy, forgiving species like a betta, tetra, or corydoras catfish is the safest start. Our best fish for beginners roundup ranks them by hardiness and ease of care. Avoid high-maintenance species (discus, marine fish) until your tank is cycled and stable.
What tank size should I start with?
Bigger is actually easier for beginners — more water volume means more stable parameters. A 10–20 gallon tank is the sweet spot for a first setup. Our best beginner fish tanks guide covers the best starter kits.
Do I need to cycle my tank before adding fish?
Yes — cycling is non-negotiable and the #1 thing beginners skip. It establishes the beneficial bacteria that process fish waste. Our nitrogen cycle guide walks you through it, and our cycling guide has the step-by-step method.
Freshwater Care
What water parameters does my fish need?
Almost every fish has specific temperature, pH, and hardness needs. Our care guides (betta, angelfish, tetras, and dozens more) each state the exact parameters. For a quick check, use our tank size calculator and cross-reference the species guide.
How often should I change the water?
For most tanks, a 20–25% water change every 1–2 weeks keeps nitrates in check. Heavily stocked tanks need more frequent changes. Test the water to confirm — nitrate should stay under 20–40 ppm.
Why is my water cloudy?
Cloudy water is usually one of three things: a bacterial bloom in a new tank (harmless, clears on its own), overfeeding, or a filter that’s too small. Our best aquarium filters guide helps you right-size filtration.
Equipment
What filter size do I need?
Aim for a filter rated to turn over your tank’s volume at least 4–5× per hour. For a 20-gallon tank, that’s a filter rated for ~80–100 GPH. See our filter comparison for recommendations by tank size.
Do I need a heater?
Freshwater tropical fish (bettas, tetras, angelfish) need the water in the low-to-mid 70s°F, so a heater is essential in most homes. Coldwater fish (goldfish, white clouds) don’t. Our best aquarium heaters guide covers sizing and reliability.
Saltwater or freshwater — which is easier?
Freshwater is far easier and cheaper for beginners. Saltwater/reef tanks demand precise water chemistry, live rock, and more specialized equipment. Our guides cover both, but we recommend starting freshwater and upgrading later if you catch the reef bug.
About AquariumLab
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We take corrections seriously. Contact us and we’ll verify and fix it, typically within 2 business days.