Aquendium
Guide

How to set up a new aquarium

From empty box to thriving tank — a step-by-step guide to setting up freshwater aquarium from scratch, covering equipment choices, assembly, cycling, and stocking.

Published 6 June 2026 · Last updated 6 June 2026 · 16 min read

The honest timeline

The single biggest expectation-mismatch in fishkeeping is timeline. Pet shops sell tanks and fish on the same day; YouTube videos show finished tanks in five-minute setup montages. The reality is that a properly-established freshwater aquarium takes 6-8 weeks from purchase to fully stocked, and the bulk of that time is spent waiting for biological processes that cannot be rushed.

Here's the honest schedule:

Skip the cycling step and your fish will die. Cut the stocking pace short and you'll trigger ammonia crashes. The timeline is the timeline, and it's worth knowing upfront so you can plan around it rather than fight it.

Phase 1 — Planning and buying

Before buying anything, two decisions shape everything else: tank size and species. Get these right and the rest follows naturally; get them wrong and you'll fight your setup forever.

Choose your tank size first, fish second

The common mistake is choosing fish first and then trying to fit them into a tank. The right order is the opposite: choose a tank size you can comfortably accommodate (physically, financially, in maintenance time), then choose fish suited to that size.

Honest tank-size guidance:

The counterintuitive truth: larger tanks are easier to keep than smaller ones. More water means slower parameter swings, more dilution of mistakes, and broader species options. A first-time keeper with a 100-litre tank will have a smoother experience than the same keeper with a 30-litre tank.

Choose your species before buying anything else

Your species selection determines your equipment choices. Tropical community fish need a heater; cool-water species don't. Soft-water species need substrate that supports low pH; hard-water species don't. Heavy bioload species need oversized filtration; nano species don't.

See our guide on choosing your first fish for detailed recommendations. The short version: pick species suited to your tank size and your local tap water, prioritising hardiness and peaceful temperament.

The essential equipment list

You need genuinely less equipment than chain pet shops suggest. The actual essentials:

The tank itself. Rectangular tanks of conventional proportions are easier to maintain than tall, narrow, or unusually-shaped tanks. Glass is more durable than acrylic for most home use. Tanks with internal bracing on the rim are stronger but slightly harder to plant; rimless tanks look better but cost more. For a first tank, a standard rectangular glass tank from any reputable Australian aquarium retailer is fine.

A filter rated for your tank size or larger. Three common types: hang-on-back filters (cheap, easy to maintain, slightly noisy, fine for tanks under 100L), internal canister filters (quiet, fine for most tanks), and external canister filters (most expensive, most powerful, best for tanks over 100L or for keepers who want to minimise in-tank visual clutter). For a first tank, hang-on-back or internal canister filtration is sufficient. Buy a filter rated for at least your actual tank size — slightly oversized is better than slightly undersized.

A heater (for tropical setups) sized to your tank. Use our heater wattage calculator to size correctly. Major brands (Eheim, Aqua One, Aquatop) all produce reliable units. Avoid cheap unbranded heaters — heater failure is one of the most common causes of mass fish deaths.

Substrate. Two main options for community tanks: fine smooth gravel or aquarium sand. Avoid sharp gravel (damages bottom-dwellers' barbels), unwashed builder's sand (too fine, clouds water), and pH-altering substrates (worth using only if you specifically need acidic water for soft-water species). About 3-5cm depth is standard; deeper for heavily-planted tanks.

A light. Most tanks come with a basic LED light included. This is fine for fish-only setups. For planted tanks, you'll eventually want a dedicated plant-spectrum LED, but you don't need this on day one.

A water test kit. The API Freshwater Master Test Kit is the most widely-used in Australian fishkeeping and stocks at most aquarium shops. Tests pH, ammonia, nitrite, and nitrate — the four numbers you'll be monitoring through cycling and beyond. Liquid test kits, not test strips.

Dechlorinator. Seachem Prime is the gold standard, widely available in Australia. A small bottle treats thousands of litres and lasts most keepers a year. Non-optional for any tap-water-based aquarium.

A thermometer. A simple stick-on or floating thermometer, mounted on the opposite side of the tank from the heater. Don't trust the heater's own dial — use a thermometer.

A gravel vacuum and dedicated bucket. For water changes. The bucket must be used only for the aquarium — household buckets often have soap residue that kills fish.

Some decor and hiding places. Driftwood, rocks (aquarium-safe types only — avoid limestone in soft-water tanks), and live or silk plants. Fish need places to hide, particularly during the stress of moving in.

Equipment to skip for now

The pet shop will try to sell you many additional items. Most are unnecessary on day one:

Phase 2 — Physical setup (day 1)

Once you have your equipment home, the physical setup happens in one session — usually 2-4 hours from empty box to filled tank.

Step 1: Position the tank before filling

Decide where the tank will live before you fill it. A filled aquarium weighs roughly 1 kilogram per litre — a 100-litre tank is 100kg plus equipment. Move the tank to its final position now, while it's empty and movable.

Choose a location that's level, sturdy enough to support the weight, away from direct sunlight (causes algae blooms), away from heating and cooling vents (causes temperature swings), and near both a power outlet and a tap (you'll be doing water changes regularly).

If you're putting the tank on a stand or cabinet, confirm the surface is genuinely level using a spirit level. An out-of-level tank stresses the glass and can crack seams over time.

Step 2: Rinse everything

Rinse the empty tank with plain water (no soap, ever) to remove manufacturing dust. Rinse all decor, rocks, and driftwood. Rinse substrate in a colander or bucket until the water runs reasonably clear — gravel and sand both ship with significant dust that will cloud your tank for days if you skip this step.

Driftwood may continue releasing tannins (yellow-brown colouration) for weeks regardless of pre-soaking; this is harmless and even slightly beneficial for soft-water species, but if you prefer crystal water, soak driftwood in a separate bucket of water for a few days before installing.

Step 3: Add substrate

Spread substrate across the tank floor at 3-5cm depth, slightly deeper toward the back for visual interest. If you're planning a planted tank, consider sloping the substrate higher at the back to give depth perspective.

Step 4: Position hardscape (rocks, driftwood, decor)

Arrange your hardscape before adding water — it's much easier to see what you're doing in an empty tank. Plan for plenty of hiding spots; new fish are particularly stressed and need cover. The classic mistake is sparse decor that leaves fish exposed; err toward more hiding places than you think you need.

For securing rocks, driftwood, or attaching plants like Anubias and Java fern to hardscape, use cyanoacrylate gel super glue — the gel form rather than liquid. Cyanoacrylate cures instantly on contact with water and is genuinely aquarium-safe once cured; it's the same chemistry used in surgical glue for skin. Standard brand-name super glues (Loctite Gel Control, Selleys Quick Fix Gel, Bostik Super Glue Gel) work fine as long as the only listed ingredient is ethyl cyanoacrylate. Avoid any super glue marketed as "extra strength" or "fast-bond" that lists additional solvents, plasticisers, or "performance additives" — these can leach into the water column. Specialty aquarium-branded glues (Seachem Reef Glue, ADA Wood Tight) are reformulated cyanoacrylate gels sold at a premium; they work no better than standard hardware-store gel super glue with the right ingredient list.

Step 5: Install equipment

Install the filter following its specific instructions — typically hung on the back or placed in a corner. Install the heater horizontally near the bottom of the tank (heat rises; positioning low gives better circulation). Don't plug anything in yet.

Step 6: Fill the tank slowly

Place a small plate or bowl on the substrate and pour water onto it — this prevents the incoming water stream from blasting your substrate around. Use room-temperature water for the first fill (subsequent water changes will need temperature-matched water, but for the initial fill, room temp is fine).

Fill to about 5cm below the rim.

Step 7: Dechlorinate

Add dechlorinator at the dose specified on your product's label — based on the total tank volume for the initial fill. Stir gently.

Step 8: Plant live plants if you're using them

If you're using live plants, plant them now while the water is in but the equipment isn't running. Sand and fine gravel are easier to plant in than coarse gravel. Don't worry about getting plants perfect — they'll grow into position over weeks.

Step 9: Start the filter and heater

Plug in the filter and confirm flow looks healthy. Plug in the heater and set it to your target temperature (24-26°C for most tropical community tanks). Add the thermometer to monitor.

Leave the tank running for 24-48 hours before doing anything else. This lets water clear from substrate dust, equipment settle into steady operation, and temperature stabilise. Do not add fish yet.

Phase 3 — Cycling (weeks 1-4)

This is the part everyone wants to skip and nobody can. A new tank has no biological filter — no beneficial bacteria to convert toxic ammonia (from fish waste) into less toxic nitrate. Adding fish to an uncycled tank is the most common cause of beginner fish deaths.

The cycling process takes 3-6 weeks and cannot be meaningfully shortened. See our complete cycling guide for the detailed procedure. The short version:

Step 1: Add an ammonia source

To grow the beneficial bacteria, you need to feed them. Two methods:

Step 2: Test daily and wait

Test ammonia, nitrite, and nitrate daily. You'll see ammonia rise, then nitrite rise as the first bacteria establish, then nitrate rise as the second wave of bacteria establish. The cycle is complete when adding ammonia produces zero ammonia and zero nitrite reading within 24 hours, with nitrate climbing.

Step 3: Do a large water change before adding fish

Once cycled, your nitrate will be high (often 80+ ppm). Do a 50% water change with dechlorinated water to bring nitrate to a safe level before adding fish.

The honest truth about "cycling boosters"

Products labelled as "instant cycle," "cycle starter," or similar promise to short-circuit the cycling process. The honest assessment: Tetra SafeStart and similar bottled bacteria products genuinely contain living nitrifying bacteria and can shorten cycles by a week or two when used correctly. They don't make cycling instant, but they help.

Cheaper or older "cycle starter" products are less reliable — bottled bacteria has a real shelf life and many products on shop shelves have been there too long to be effective. If you use bottled bacteria, buy the freshest stock you can find, refrigerate it, and treat it as a head-start rather than a substitute for proper cycling.

Phase 4 — Adding your first fish

Once your tank is cycled and you've done a large water change, you can add the first wave of fish. This is the moment all the preparation has been building toward.

Step 1: Don't buy everything at once

Even with a fully cycled tank, your bacteria colony is sized for the ammonia load used to cycle. Adding all your intended fish in one trip overwhelms the colony and causes a mini-cycle — small ammonia and nitrite spikes that stress fish.

For a community tank, plan to add roughly a third of your intended stock now, another third in 2 weeks, and the final third in 4 weeks.

Step 2: Choose healthy fish from the shop

The fish you bring home is only as healthy as the shop you bought it from. See our guide on buying healthy fish for full detail. Briefly: look for active fish, intact fins, no white spots, no dead or dying fish in the same shop tank, and ask how long the fish have been in the shop.

Step 3: Acclimate properly at home

Fish in transport bags experience stress, temperature changes, and water chemistry changes. Sudden release into your tank compounds the stress.

The drip-acclimation method is the safest: float the bag in your tank for 15-20 minutes to equalise temperature, then over 30-60 minutes, gradually mix small amounts of tank water into the bag (a few tablespoons every 5 minutes). Finally, net the fish out of the bag and release into the tank — discard the bag water rather than pouring it in, to avoid introducing shop diseases.

Step 4: Watch carefully for the next week

Test ammonia and nitrite daily for the first 1-2 weeks after adding fish. If either becomes detectable, do an immediate water change and dose Prime — your bacteria colony is adjusting to the new bioload.

Don't feed for the first 24 hours. Stressed fish often don't eat anyway, and uneaten food pollutes water at the worst possible moment.

Phase 5 — Building toward your full stocking

Over the following weeks, add the remaining fish in stages. Test before each addition. If parameters stay stable, proceed; if not, wait longer before the next addition.

Once your full stocking is in place, switch from daily testing to weekly testing of nitrate (as a sanity check before water changes) and monthly testing of pH, GH, and KH. See our water parameters guide for the complete reference.

From here, your routine becomes:

What not to buy (common starter-kit mistakes)

The honest list of products that look reasonable but cause problems:

"All-in-one" starter kits with tiny tanks

Kits marketed as "first aquariums" often include tanks under 20 litres with built-in filtration and a single goldfish or betta on the box. These small tanks are harder to maintain than larger ones, and the included filters are usually inadequate. Buy a proper 40L+ tank with separate equipment.

"Cycling fish" or "starter fish"

Some shops still recommend adding a couple of "hardy fish" to a new tank to cycle it. This is animal cruelty — those fish suffer through the ammonia and nitrite spikes you're trying to prevent. Use fishless cycling.

Goldfish for a "starter tank"

Goldfish are cold-water fish that grow to 30cm and live 15+ years, producing enormous bioloads. They are not appropriate for "starter tanks" under 200L. If you specifically want goldfish, plan a 200L+ unheated tank from the start.

Common plecos as "algae cleaners"

Fish sold simply as "plecos" at chain shops are almost always common plecos (Hypostomus plecostomus) which reach 60cm and need 750+ litre tanks. For a community tank algae-eater, buy a bristlenose pleco (stays at 12cm) instead.

Bettas in "betta cubes"

The 1-2 litre cube tanks sold for bettas are inhumane. Bettas need at least 30 litres, with a heater and gentle filter. Don't buy these regardless of how convenient they look.

Coloured gravel that fades and stains

Bright dyed gravel often fades over months and can stain silicone seams. Natural-coloured gravel or sand looks better long-term and is significantly cheaper.

Plastic plants that damage fish

Cheap plastic plants often have sharp edges that tear fins, particularly on long-finned species like bettas and gouramis. Silk plants are safer; live plants are best.

Australian-specific considerations

A few things worth knowing if you're setting up in Australia specifically:

Your tap water determines everything. Most of Australia has hard, alkaline tap water (Brisbane, Gold Coast, Adelaide, Perth) which strongly favours hard-water species (livebearers, snails, African cichlids) and makes soft-water species (neon tetras, discus, shrimp) significantly harder to keep. Test your tap water before buying fish. See our water parameters guide for regional profiles.

Chloramine, not chlorine, is now standard. Most Australian municipal supplies use chloramine for disinfection. Chlorine evaporates if water is left standing; chloramine does not. Dechlorinator (specifically one that handles chloramine, like Seachem Prime) is non-negotiable.

Check your local restrictions before buying fish. Some species are restricted in specific Australian states due to invasive risk. Weather loaches are restricted in Victoria; some snails are restricted in various states. Major aquarium retailers know their local restrictions, but worth confirming for any unusual species.

Australian electricity standards. All aquarium equipment sold in Australia should be Australian-certified for the 240V mains. Avoid imported equipment from overseas (eBay, AliExpress) that may not be electrically safe — water and electricity is not an area to economise.

Climate matters for unheated tanks. South East Queensland and Northern Australia rarely need heaters for tropical fish during summer; southern states do year-round. Cool-water species (white cloud minnows, weather loaches, rosy barbs) thrive in unheated tanks across most of southern Australia.

Once your tank is set up and cycled, see our guides on water changes, water parameters, choosing your first fish, and common fish diseases. For individual species' care requirements, browse our species directory.

Top