From choosing a tank to your first fish — a week-by-week plan that keeps beginners clear of the common early mistakes.
By Lin Wei · 2026-09-14
Most failed first tanks fail before the first purchase. Decide three things first: where the tank will sit (away from direct sun and drafts, near a power outlet, on a stand that can hold ten times the tank's weight in kilograms), what temperature your room holds year-round, and how much time you genuinely have each week.
For a first planted tank, 40–60 litres is the sweet spot: large enough to stay chemically stable, small enough to afford, light, and rescape. A 60 × 30 × 36 cm tank fits a standard 60 cm LED and gives you real aquascaping room.
Rinse the substrate until the water runs almost clear, slope it higher at the back, and hardscape before any water goes in. One stone group and one piece of driftwood is enough for a first layout; negative space is not emptiness, it is what makes the layout readable.
Plant densely from day one. Fast growers — pearlweed, hornwort, water sprite, Vallisneria — out-compete algae for nutrients while the tank matures. Use tweezers, plant in small clumps, and trim nothing for the first two weeks.
Fill slowly, pouring onto a plastic bag to protect the substrate slope, then start the filter and let the tank run planted and unstocked.
This is the nitrogen cycle doing its slow work (see our dedicated article on it). Test ammonia and nitrite every two or three days. You will typically see ammonia appear around week two, peak, then fall as nitrite rises and, finally, nitrate accumulates.
Do small water changes — 20% twice a week — whenever ammonia or nitrite reads above 0.25 ppm. Dose a bacterial starter if you have one, but understand it accelerates rather than replaces the wait.
Start the light at 6 hours a day and increase slowly to 8. Early diatom ('brown dust') algae is normal and disappears on its own; resist the urge to scrub everything spotless.
Once a dose of ammonia converts to nitrate within 24 hours, the tank is cycled. Change 50% of the water, let it settle for a day, and then add a small first group of genuinely hardy fish — white cloud mountain minnows are the classic choice because they tolerate the cool, slightly-fluctuating water of a new tank.
Add at most one small group in the first week. Feed once a day, sparingly. Every new addition is a new ammonia source, and the bacterial colony must grow to match it.
Settle into a weekly rhythm: 25% water change, glass cleaning, filter intake rinse, prune the fastest growers, and one water test. Tanks rarely die from one big mistake; they decline through neglected small habits.
Expect to replant and adjust the layout at least once — every experienced aquascapist's first tank looked nothing like it did at month one, and that is part of the hobby.
Typically 3–5 weeks. The tank is ready when both ammonia and nitrite read zero 24 hours after a test dose of ammonia or a pinch of food, and only nitrate accumulates. Adding fish earlier exposes them to ammonia burns and nitrite poisoning.
No. Choose undemanding plants — Vallisneria, Cryptocoryne, Anubias, Java fern, pearlweed — and a decent full-spectrum LED, and they will grow well without added CO2. CO2 becomes relevant only when you chase demanding, high-light carpeting species.
Melting is normal for plants grown emersed (above water) adapting to submerged life — prune the dying leaves and new submerged growth will follow. Yellowing of older leaves usually means nitrogen or potassium shortage, which a small weekly liquid fertiliser dose fixes within two weeks.
Yes, and it is the recommended way. Plants absorb ammonia directly and seed the filter with bacteria on their surfaces, often shortening the cycle. Keep lighting moderate and expect some early algae.
Once a day, only what is eaten within two minutes. A new filter and immature bacterial colony handle waste poorly; uneaten food is the most common cause of mid-cycle ammonia spikes.