Beginner aquarium setup: tank size, filter, heater, and lighting (what actually matters)

Quick answer

For most beginners, a 40L to 80L freshwater tank with a reliable filter, a heater (for tropical fish), a thermometer, and a timer-controlled light is the sweet spot. Bigger tanks are more stable. Avoid tiny tanks, cheap unfiltered bowls, and "all-in-one" gadgets that are hard to maintain.

Tank size: bigger is easier

Water changes slowly in a bigger tank. That means fewer sudden swings in temperature and water quality.

• Best beginner range: 40L to 80L
• Okay if space is tight: 20L to 40L (choose hardy fish and stock lightly)
• Avoid as a first tank: under 20L unless you know exactly what you are doing

If you are stuck between two sizes, choose the bigger one.

Filters: choose stability over power

A filter is both a cleaner and your main "biological engine".

• Sponge filter: gentle, great for small tanks and fry
• Hang-on-back (HOB): easy to service, good flow control
• Canister filter: excellent for larger tanks, but more complex

What matters most:

• Consistent flow (not blasting fish around)
• Media you can keep (do not replace everything at once)
• Easy maintenance (you will actually do it)

Heaters: only if you keep tropical fish

Many popular beginner fish are tropical and want stable warmth.

• Use a heater with a thermostat and pair it with a thermometer.
• Place the heater where water flow passes it so heat spreads evenly.
• Aim for stability over chasing exact numbers.

Coldwater setups can work too, but they need fish that truly tolerate cooler temperatures.

Lighting: avoid algae drama

Light is for you, your plants, and your fish's day-night rhythm.

• Use a timer.
• Start with 6 to 8 hours/day.
• If algae explodes, reduce light and review feeding and water changes.

If you want live plants, pick easy ones (anubias, java fern, floaters) and keep the light moderate.

Substrate and decor: make it fish-friendly

• Sand: great for bottom dwellers, looks natural
• Gravel: easy, forgiving, works for most community fish

Add hiding places. Fish feel safer and behave better when they can retreat.

A beginner shopping list (minimal, realistic)

• Tank + lid
• Filter + media
• Heater (if tropical) + thermometer
• Dechlorinator
• Liquid test kit (ammonia, nitrite, nitrate)
• Net, siphon, bucket (tank-only)
• Food appropriate for your species
• Timer for lights

FAQ

Is a "starter kit" tank a good idea?

Some are great, some cut corners. If you buy a kit, check the filter quality and confirm replacement parts are easy to get.

Do I need an air pump?

Not always. Many filters provide surface agitation. An air stone can help oxygenation, especially in warm water or heavily stocked tanks.

Should I buy a fancy CO2 system for plants?

Not for a first tank. Start with low-tech plants and consistent routines.

Next step

Want a fish match that fits your space, time, and comfort level with maintenance?